{"gene":"SH2D1A","run_date":"2026-04-28T20:42:07","timeline":{"discoveries":[{"year":1998,"finding":"SH2D1A (SAP) was identified as the gene mutated in X-linked lymphoproliferative syndrome (XLP); it encodes a 128-amino-acid protein composed almost entirely of a single SH2 domain, expressed in T and NK cells, that acts as an inhibitor by blocking recruitment of the SH2-domain-containing signal-transduction molecule SHP-2 to a docking site in the SLAM (CD150) cytoplasmic region.","method":"Positional cloning, mutation analysis in XLP patients, co-immunoprecipitation, functional blocking assay","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1-2 — original discovery paper with multiple methods, independently confirmed by concurrent papers (Coffey et al., Nichols et al.)","pmids":["9774102","9771704","9811875"],"is_preprint":false},{"year":1999,"finding":"Crystal structures of SAP revealed it binds both phosphorylated and non-phosphorylated SLAM peptides using a mode that involves specific interactions with residues N-terminal to the tyrosine in addition to C-terminal contacts ('extended, phosphotyrosine-independent sequence recognition'), recognizing the motif TIpYXX(V/I). XLP-causing mutations were shown to disrupt these interactions.","method":"X-ray crystallography, phosphopeptide library screen, mutagenesis","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 — crystal structures with mutagenesis and peptide library validation","pmids":["10549287"],"is_preprint":false},{"year":1999,"finding":"The SAP SH2 domain binds SLAM peptides in a phosphorylation-independent manner with Kd ~330 nM (non-phospho) and ~150 nM (phospho), and NMR studies demonstrated a 'three-pronged' binding mechanism engaging both N-terminal and C-terminal residues flanking the tyrosine, distinct from canonical SH2 'two-pronged' binding.","method":"NMR spectroscopy (15N/13C-labeled SAP), fluorescence binding assays","journal":"Current biology","confidence":"High","confidence_rationale":"Tier 1 — multi-field NMR with quantitative binding data, independently consistent with crystal structures","pmids":["10607564"],"is_preprint":false},{"year":2001,"finding":"SAP regulates SLAM-mediated signaling in T cells by facilitating selective recruitment and activation of the Src-family kinase FynT to SLAM; in the absence of SAP, SLAM fails to trigger protein tyrosine phosphorylation and downstream signals involving SHIP, Dok2, Dok1, Shc, and RasGAP. SAP is thus an adaptor for FynT rather than merely an inhibitor of SHP-2.","method":"Reconstitution in T cell lines, co-immunoprecipitation, dominant-negative/knockout approaches, signaling assays in SAP-deficient cells","journal":"Nature immunology","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods, reciprocal co-IP, loss-of-function with defined signaling phenotype","pmids":["11477403"],"is_preprint":false},{"year":2001,"finding":"SAP associates with the novel SLAM-family receptor NTB-A (a 60-kD glycoprotein on NK, T, and B cells). In XLP-NK cells lacking SAP, NTB-A delivers inhibitory rather than activating signals, contributing to the inability of XLP-NK cells to kill EBV-infected B cells. SAP prevents NTB-A from recruiting inhibitory SHPs.","method":"Molecular cloning, co-immunoprecipitation, NK cell cytotoxicity assays with XLP patient cells, antibody-blocking experiments","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 2 — reciprocal co-IP, patient-derived cells, functional cytotoxicity readout","pmids":["11489943"],"is_preprint":false},{"year":2001,"finding":"In B cells, SAP (SH2D1A) determines which phosphatase associates with CD150 (SLAM): when SAP is present, SHIP is recruited to phosphorylated Y281 and Y327 of CD150; when SAP is absent (as in XLP B cell lines), SHP-2 associates instead. SAP thus functions as a molecular switch (via the TxYxxV/I 'immunoreceptor tyrosine-based switch motif') regulating alternative downstream signaling.","method":"Co-immunoprecipitation, GST-fusion pulldowns with Y→F mutants of CD150, comparison of SAP-positive vs. SAP-negative B cell lines","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 2 — multiple cell lines, site-directed mutagenesis of binding motifs, comparison with XLP patient lines","pmids":["11313386"],"is_preprint":false},{"year":2001,"finding":"SAP (SH2D1A) binds the SH3 domain of FynT directly, an interaction mediated through the surface of the SAP SH2 domain. In cells, FynT is indispensable for SLAM tyrosine phosphorylation and SAP dramatically enhances this phosphorylation while blocking SHP-2 recruitment. Disease-causing SAP mutants show significantly reduced affinity for both FynT and SLAM, confirming the dual adaptor/inhibitor role.","method":"In vitro peptide array binding, in vivo co-immunoprecipitation, kinase assays, site-directed mutagenesis of disease mutants","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1-2 — in vitro and in vivo binding assays plus disease mutant analysis with orthogonal methods","pmids":["12458214"],"is_preprint":false},{"year":2002,"finding":"NMR structures of the SAP SH2 domain in complex with SLAM-derived peptides (with and without phosphotyrosine) provided direct structural evidence for the 'three-pronged' binding mechanism. The consensus binding sequence T/S-x-x-x-x-V/I (lacking Tyr or pTyr) is recognized via a surface distinct from canonical SH2 engagement. Structural mapping explained binding defects in XLP-causing SAP mutants.","method":"NMR structure determination, hydrogen exchange, synthetic peptide repertoire screening, disease mutant structural analysis","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1 — high-resolution NMR structures with functional validation and disease mutant analysis","pmids":["11823424"],"is_preprint":false},{"year":2001,"finding":"Analysis of XLP missense mutations identified two classes: (i) mutations reducing SAP protein half-life (Y7C, S28R, Q99P, P101L, V102G, X129R) and (ii) mutations that structurally impair binding to SLAM-family receptors (CD150, CD84, CD229, CD244). Mutant T53I selectively abolishes phosphorylation-independent interactions while preserving phosphotyrosine-dependent binding, and abrogates binding to CD229/CD224, demonstrating that SAP controls multiple distinct signaling pathways.","method":"Site-directed mutagenesis, protein half-life assays, GST-pulldown and co-immunoprecipitation with four SLAM-family receptors","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — systematic mutagenesis of 10 disease-causing alleles with multiple receptor binding assays","pmids":["11477068"],"is_preprint":false},{"year":2003,"finding":"Crystal structure of a ternary SLAM-SAP-Fyn-SH3 complex showed that the SAP SH2 domain binds the FynT SH3 domain through a non-canonical surface-surface interaction (not involving canonical SH3 or SH2 binding motifs), directly coupling FynT to SLAM. This binding mode is predicted to preclude Fyn's autoinhibited conformation, thereby promoting kinase activation upon recruitment.","method":"X-ray crystallography of ternary complex, biochemical binding assays","journal":"Nature cell biology","confidence":"High","confidence_rationale":"Tier 1 — ternary complex crystal structure with mechanistic interpretation confirmed by biochemical data","pmids":["12545174"],"is_preprint":false},{"year":1999,"finding":"SAP was shown to associate with 2B4 (CD244) on activated human NK cells and T cells, and this interaction prevented 2B4 from recruiting SHP-2. Loss of SAP in XLP leads to aberrant inhibitory signaling through 2B4, extending the pathological mechanism beyond SLAM to include other SLAM-family receptors.","method":"Co-immunoprecipitation in activated cells, functional assays with pervanadate-stimulated transfectants","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 2 — reciprocal co-IP in primary cells and transfected cells, mechanistic follow-up with competition experiments","pmids":["10358138"],"is_preprint":false},{"year":2001,"finding":"Cell surface receptors Ly-9 (CD229) and CD84 also recruit SAP through their cytoplasmic TxYxxV/I motifs, particularly when their tyrosine residues are phosphorylated, as shown by yeast two-hybrid, COS cell transfection, and lymphoid cell assays. SAP regulation of SLAM-family signaling therefore extends to at least four receptors (SLAM, 2B4, CD84, Ly-9).","method":"Yeast two-hybrid, COS cell co-transfection/co-immunoprecipitation, lymphoid cell co-immunoprecipitation","journal":"Blood","confidence":"High","confidence_rationale":"Tier 2 — multiple independent experimental systems confirming SAP interaction with two new receptors","pmids":["11389028"],"is_preprint":false},{"year":2000,"finding":"SH2D1A (SAP) associates with Dok1 (p62dok) in a manner dependent on phosphorylation of Dok1 Y449; an XLP-associated SH2 domain mutant fails to associate with Dok1. Overexpression of SH2D1A activates NF-κB in 293T cells through a mechanism requiring IκB kinase β but independent of the SH2 domain.","method":"Co-immunoprecipitation, lane-shift SH2 domain mutant analysis, NF-κB reporter assays, dominant-negative IKKβ","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2-3 — single-lab study with co-IP and reporter assays; NF-κB activation mechanism not further validated","pmids":["10852966"],"is_preprint":false},{"year":2002,"finding":"SAP (SH2D1A) association with 2B4 in NK cells is dependent on PI3K activity: PI3K inhibitors (wortmannin, LY294002) prevent SAP recruitment to 2B4 after 2B4 ligation without altering the 2B4–p85 association, and PI3K inhibition significantly reduces NK cell cytotoxicity in a SAP-dependent manner.","method":"Co-immunoprecipitation with pharmacological PI3K inhibitors in primary NK cells, NK cell cytotoxicity assays, XLP patient NK cells as controls","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 3 — single-lab study using pharmacological inhibitors with functional readout; PI3K-SAP mechanistic link not further molecularly dissected","pmids":["11815622"],"is_preprint":false},{"year":2004,"finding":"CD150 (SLAM)-mediated Akt phosphorylation in B cells requires Syk and SH2D1A (SAP), is negatively regulated by Lyn and Btk, and is SHIP-independent. CD150-mediated ERK activation requires SHIP but not SAP. SAP thus acts as a switch between CD150-initiated signaling pathways, directing signaling towards Akt rather than ERK.","method":"DT40 B cell sublines deficient in specific signaling molecules, stimulation assays, phospho-specific western blotting","journal":"Blood","confidence":"Medium","confidence_rationale":"Tier 2 — genetic epistasis in isogenic DT40 knockout cell lines with two defined pathway readouts","pmids":["15315965"],"is_preprint":false},{"year":2004,"finding":"SH2D1A-deficient mice cannot form germinal centers upon immunization, and both SAP-deficient T cells and B cells have functional defects impairing T-dependent IgG antibody responses. Adoptive co-transfer experiments demonstrated that SAP expression is required in B cells for antigen-specific IgG production, identifying a B cell-intrinsic role for SAP.","method":"Knockout mouse model, adoptive co-transfer experiments (KO B cells + WT T cells, and vice versa), germinal center histology","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 — genetic epistasis with adoptive transfer and germinal center analysis, defining cell-autonomous B cell role","pmids":["15774582"],"is_preprint":false},{"year":2004,"finding":"SH2D1A deficiency protects mice from T-dependent humoral autoimmunity (experimental lupus) by blocking germinal center formation and T-dependent antibody responses, while leaving T-independent responses intact. This identifies the SLAM-SH2D1A axis as specifically required for T-dependent humoral immunity.","method":"Sh2d1a−/− mouse lupus model, germinal center analysis, T-dependent vs. T-independent immunization, EAE susceptibility","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 2 — multiple disease models in KO mice with mechanistic dissection of T-dependent vs. T-independent pathways","pmids":["15263031"],"is_preprint":false},{"year":2004,"finding":"SAP and the SLAM-family receptor NTB-A cooperate to regulate TCR-induced restimulation-induced cell death (RICD) in activated T cells. SAP/NTB-A signaling augments proximal TCR signaling strength to reach the threshold for apoptosis; upon TCR restimulation, SAP is increasingly recruited to NTB-A while SHP-1 dissociates. SAP-deficient T cells (XLP) resist RICD, and blocking NTB-A in normal T cells recapitulates XLP-like RICD resistance.","method":"XLP patient T cells, siRNA knockdown, antibody blockade, co-immunoprecipitation time-course, apoptosis assays","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 — patient-derived cells plus knockdown/blockade with mechanistic molecular readouts and apoptosis phenotype","pmids":["19759517"],"is_preprint":false},{"year":2005,"finding":"SAP is essential for NKT cell development in both mice and humans; Sh2d1a−/− mice and XLP patients (confirmed by germline SH2D1A mutations) completely lack NKT cells in thymus and periphery. The defect is hematopoietic cell-autonomous and rescued by reconstitution of SAP expression in bone marrow. Female XLP carriers show completely skewed X-chromosome inactivation within NKT cells but not T or B cells.","method":"Knock-out mouse analysis, analysis of XLP patient lymphocyte subsets, bone marrow reconstitution, X-inactivation skewing analysis in XLP carriers","journal":"Nature medicine / The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 2 — two independent labs (Nichols et al. and Pasquier et al.) confirmed SAP-dependent NKT development with cell-autonomous rescue","pmids":["15711562","15738056"],"is_preprint":false},{"year":2005,"finding":"SAP-deficient CTLs from XLP patients show specific lytic defects against EBV-positive B cells, associated with impaired polarization of 2B4, perforin, and lipid rafts to the contact zone. Blockade of 2B4 in normal CTLs reproduces the SAP-deficient polarization defect, demonstrating that the SAP/2B4 pathway directs lytic machinery polarization toward EBV-positive targets.","method":"XLP patient CTL cytotoxicity assays, immunofluorescence microscopy of immunological synapse, 2B4 antibody blockade","journal":"Blood","confidence":"High","confidence_rationale":"Tier 2 — patient cells plus antibody blockade mimicking KO phenotype with defined polarization readout","pmids":["15677558"],"is_preprint":false},{"year":2005,"finding":"2B4 signals activate NK cells through a mechanism strictly dependent on SAP: SAP binds all 4 ITSMs of 2B4 in a phosphorylation-dependent manner and acts as an inhibitor of negative regulators (SHP-1, SHP-2, SHIP, Csk) at the third ITSM. Fyn can also associate with phosphorylated 2B4, and both Fyn and Csk can phosphorylate 2B4.","method":"Structure-function mutagenesis of 2B4 ITSMs, co-immunoprecipitation, kinase phosphorylation assays in NK cell lines","journal":"Blood","confidence":"High","confidence_rationale":"Tier 1-2 — systematic ITSM mutagenesis with kinase assays and competitive binding experiments","pmids":["15713798"],"is_preprint":false},{"year":2004,"finding":"2B4-induced tyrosine phosphorylation signaling in NK cells (involving 2B4, Vav-1, and SHIP-1) is absolutely dependent on co-expression of SAP and requires Arg78 of SAP (the FynT-binding residue). This confirmed that SAP promotes 2B4 signaling by recruiting FynT, and established that SLAM and 2B4 trigger distinct tyrosine phosphorylation profiles despite both requiring SAP.","method":"NK cell line reconstitution, structure-function mutagenesis (R78 of SAP), co-immunoprecipitation, tyrosine phosphorylation assays","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 — SAP point mutant specifically disrupting FynT binding eliminates 2B4 signaling; genetic epistasis in reconstituted cells","pmids":["15169881"],"is_preprint":false},{"year":2008,"finding":"SAP interacts with the SH3 domains of NCK1 (a novel binding partner) as well as FynT via the same surface on the SAP SH2 domain. NMR analysis showed NCK1-SH3 and Fyn-SH3 engage the same residues on SAP with comparable affinities. SAP depletion by siRNA reduces NCK1 tyrosine phosphorylation and downstream TCR signaling (LAT, SLP-76 phosphorylation) and impairs T cell proliferation via the MAP kinase Erk pathway.","method":"SH3 domain panel screen, NMR binding analysis, siRNA knockdown, phospho-western blotting, T cell proliferation assays","journal":"Cellular signalling","confidence":"Medium","confidence_rationale":"Tier 2 — NMR binding plus siRNA phenotype with defined signaling readouts, single-lab study","pmids":["18951976"],"is_preprint":false},{"year":2004,"finding":"SH2D1A gene expression is controlled by a combination of transcriptional and post-transcriptional mechanisms: the basal promoter contains an Ets consensus site bound by Ets-1 and Ets-2 (shown by gel mobility shift/supershift and dominant-negative overexpression). SH2D1A mRNA is rapidly degraded in T cells via its 3' UTR through a balance between destabilizing factor AUF1 and stabilizing factor HuR, though the degradation rate itself is not altered by TCR engagement.","method":"Promoter deletion analysis, gel mobility shift and supershift assays, dominant-negative transcription factor overexpression, RNA decay assays, RNA-gel mobility shift assays","journal":"European journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 — multiple molecular assays identifying transcriptional and post-transcriptional regulators, single-lab study","pmids":["15459902"],"is_preprint":false},{"year":2006,"finding":"XLP missense mutations (Y54C, I84T, F87S) and an insertion (fs82→X103) each dramatically reduce SAP protein half-life. Y54C and F87S additionally impair receptor binding, while I84T does not affect binding to SLAM, CD84, or 2B4 but nonetheless reduces downstream SLAM signaling, demonstrating that reduced SAP stability is sufficient to impair signaling even when binding affinity is preserved.","method":"Patient-derived lymphocytes and transfected cell lines, protein stability assays, receptor co-immunoprecipitation, downstream signaling assays","journal":"International immunology","confidence":"Medium","confidence_rationale":"Tier 2 — four distinct disease alleles characterized with protein stability and functional assays, single lab","pmids":["16720617"],"is_preprint":false},{"year":2011,"finding":"In female XLP carriers (natural mixed SAP+/SAP- chimeras due to random X-inactivation), EBV-specific CD8+ T cells were exclusively SAP+, while CMV- and influenza-specific memory cells were distributed across both populations. Blocking SLAM receptors NTB-A and 2B4 (not EBV itself) restored cytotoxicity of SAP- CD8+ T cells against EBV-infected B cells; ectopic NTB-A expression on fibroblasts inhibited SAP- CTL cytotoxicity. This demonstrated that SLAM receptors acquire inhibitory function in the absence of SAP and that susceptibility to EBV in XLP reflects the nature of the antigen-presenting cell (B cells express SLAM receptors), not a direct effect of EBV.","method":"Human XLP carrier lymphocyte analysis, SLAM receptor blockade experiments, ectopic NTB-A expression on fibroblasts, antigen-specific T cell functional assays","journal":"PLoS biology","confidence":"High","confidence_rationale":"Tier 2 — natural human chimera model with mechanistic gain-of-function and blockade experiments, multiple orthogonal approaches","pmids":["22069374"],"is_preprint":false},{"year":2016,"finding":"SAP-deficient T cells exhibit impaired TCR restimulation-induced cell death (RICD) due to diminished TCR-induced inhibition of diacylglycerol kinase α (DGKα), leading to increased DAG metabolism and decreased Ras/PKCθ signaling. Pharmacological or genetic inhibition of DGKα in SAP-deficient T cells restores DAG signaling at the immune synapse and rescues RICD via NUR77 and NOR1 pro-apoptotic proteins. DGKα inhibition also prevents excessive CD8+ T cell expansion and IFN-γ in SAP-deficient mice after LCMV infection without impairing lytic activity.","method":"SAP-deficient T cells from XLP patients, DGKα inhibitors, in vivo LCMV mouse model, immune synapse imaging, apoptosis/signaling assays","journal":"Science translational medicine","confidence":"High","confidence_rationale":"Tier 1-2 — mechanistic pathway dissection with pharmacological rescue in patient cells and in vivo mouse model","pmids":["26764158"],"is_preprint":false},{"year":2003,"finding":"Differential methylation of CpG-rich regions in the 5' region and exon 1 of the SH2D1A gene correlates with cell lineage-specific transcription: the gene is hypomethylated in T/NK cells (which express it) and hypermethylated in B cells and granulocytes (which do not).","method":"Bisulfite sequencing, methylation-sensitive restriction enzyme digestion","journal":"Immunogenetics","confidence":"Medium","confidence_rationale":"Tier 3 — correlation of methylation with expression across cell types, no causal intervention experiment","pmids":["12709835"],"is_preprint":false}],"current_model":"SH2D1A encodes SAP, a lymphocyte-specific adaptor protein composed of a single SH2 domain that binds SLAM-family receptors (SLAM/CD150, 2B4/CD244, NTB-A, CD84, Ly-9) via a unique 'three-pronged,' partially phosphorylation-independent mechanism; SAP serves dual functions—blocking recruitment of inhibitory SHP-2/SHP-1 phosphatases to these receptors, and recruiting/activating the Src-family kinase FynT via a non-canonical SH2-SH3 surface interaction—thereby promoting positive signaling cascades required for NKT cell development, germinal center formation, T-dependent humoral immunity, NK/CTL cytotoxicity, and TCR restimulation-induced apoptosis, with loss of SAP causing inappropriate inhibitory SLAM-family receptor signaling and the immunopathology of X-linked lymphoproliferative disease."},"narrative":{"teleology":[{"year":1998,"claim":"Positional cloning of SH2D1A as the gene mutated in X-linked lymphoproliferative disease established that a single-SH2-domain adaptor protein controls SLAM signaling by competing with SHP-2 for binding to SLAM's cytoplasmic tail — defining the molecular basis of XLP.","evidence":"Positional cloning, mutation analysis in XLP families, co-immunoprecipitation and SHP-2 competition assays","pmids":["9774102","9771704","9811875"],"confidence":"High","gaps":["Mechanism by which SAP loss causes the diverse clinical manifestations of XLP was unknown","Whether SAP interacts with receptors beyond SLAM was not addressed"]},{"year":1999,"claim":"Structural studies revealed that SAP employs a unique three-pronged binding mode recognizing residues N-terminal and C-terminal to the tyrosine — explaining how SAP engages both phosphorylated and non-phosphorylated SLAM peptides and why XLP mutations disrupt these contacts.","evidence":"X-ray crystallography and NMR of SAP–SLAM peptide complexes, phosphopeptide library screening, quantitative fluorescence binding","pmids":["10549287","10607564"],"confidence":"High","gaps":["How this binding mode translated into downstream signaling beyond SHP-2 blocking was unknown","Whether non-canonical binding extended to other SLAM-family receptors was untested"]},{"year":1999,"claim":"Discovery that SAP associates with 2B4 (CD244) on NK cells and blocks SHP-2 recruitment extended the SAP-controlled signaling network beyond SLAM to other SLAM-family receptors, broadening the molecular explanation for NK cell dysfunction in XLP.","evidence":"Co-immunoprecipitation in activated primary NK cells and transfectants","pmids":["10358138"],"confidence":"High","gaps":["Full repertoire of SLAM-family receptors engaging SAP was not yet defined","The positive signaling arm downstream of SAP at 2B4 was uncharacterized"]},{"year":2001,"claim":"Reconstitution experiments overturned the purely inhibitory model of SAP by showing it actively recruits and activates FynT to SLAM, enabling downstream phosphorylation cascades involving SHIP, Dok1/2, Shc, and RasGAP — redefining SAP as a dual adaptor/blocker.","evidence":"SAP-deficient T cell reconstitution, dominant-negative FynT, co-immunoprecipitation, kinase assays","pmids":["11477403","12458214"],"confidence":"High","gaps":["Structural basis for the non-canonical SAP SH2–FynT SH3 interaction was not yet resolved","Whether FynT recruitment was required for all SLAM-family receptor signaling was unknown"]},{"year":2001,"claim":"Identification of NTB-A, CD84, and Ly-9 as additional SAP-binding SLAM-family receptors, together with the ITSM molecular switch concept (SAP presence directing SHIP recruitment at SLAM instead of SHP-2), established SAP as a global regulator of an entire receptor family.","evidence":"Co-immunoprecipitation, yeast two-hybrid, GST-pulldown with Y→F mutants, XLP patient B cell lines","pmids":["11489943","11389028","11313386"],"confidence":"High","gaps":["Relative functional importance of individual SLAM-family receptors in XLP pathology was unclear","B cell-intrinsic SAP functions had not been tested in vivo"]},{"year":2001,"claim":"Systematic characterization of XLP missense mutations identified two pathogenic mechanisms — reduced protein stability and impaired receptor binding — and showed that mutation T53I selectively ablates phosphorylation-independent binding, dissecting distinct SAP interaction modes.","evidence":"Ten disease alleles analyzed by site-directed mutagenesis, protein half-life assays, GST-pulldown with four SLAM-family receptors","pmids":["11477068"],"confidence":"High","gaps":["Genotype–phenotype correlations in XLP patients were not addressed","Whether stability-reducing mutations could be pharmacologically rescued was unknown"]},{"year":2003,"claim":"The ternary SLAM–SAP–FynT crystal structure revealed a non-canonical SH2–SH3 surface interaction that directly couples FynT to the receptor and is predicted to relieve Fyn autoinhibition, providing the structural mechanism for SAP-mediated kinase activation.","evidence":"X-ray crystallography of ternary complex, biochemical binding validation","pmids":["12545174"],"confidence":"High","gaps":["Direct demonstration that the ternary complex relieves Fyn autoinhibition in cells was lacking","Whether other SH3-domain proteins (e.g. NCK1) compete for the same SAP surface was untested"]},{"year":2004,"claim":"In vivo studies in SAP-deficient mice demonstrated that SAP is indispensable for germinal center formation and T-dependent humoral immunity, with adoptive transfer experiments revealing a B cell-intrinsic role for SAP, while protection from lupus models identified the SLAM–SAP axis as a specific checkpoint for autoimmune humoral responses.","evidence":"Sh2d1a−/− mice, adoptive co-transfer of SAP-KO vs. WT B and T cells, germinal center histology, lupus and EAE models","pmids":["15774582","15263031"],"confidence":"High","gaps":["Molecular mechanism of SAP function within B cells during germinal center reactions was undefined","Whether SAP loss in T follicular helper cells was the dominant defect was debated"]},{"year":2004,"claim":"FynT Arg78-dependent reconstitution of 2B4 signaling in NK cells confirmed that SAP promotes activating 2B4 signals by recruiting FynT, and revealed SLAM and 2B4 trigger distinct downstream phosphorylation profiles despite sharing SAP/FynT dependency.","evidence":"NK cell line reconstitution with SAP R78A mutant, co-immunoprecipitation, phosphorylation assays","pmids":["15169881","15713798"],"confidence":"High","gaps":["Receptor-specific downstream signaling pathways were incompletely mapped","How SLAM-family receptors cooperate or compete for limited SAP was unknown"]},{"year":2005,"claim":"SAP was shown to be absolutely required for NKT cell development in both mice and humans, with XLP carriers showing complete X-inactivation skewing in the NKT compartment — demonstrating a non-redundant developmental checkpoint controlled by SAP.","evidence":"Sh2d1a−/− mice, XLP patient lymphocyte subsets, bone marrow reconstitution, X-inactivation analysis in female carriers","pmids":["15711562","15738056"],"confidence":"High","gaps":["Stage of NKT cell development blocked by SAP deficiency was not precisely defined","Which SLAM-family receptor(s) mediate SAP-dependent NKT selection was unknown"]},{"year":2005,"claim":"SAP-deficient CTLs from XLP patients showed defective polarization of perforin, 2B4, and lipid rafts toward EBV-infected B cells, with 2B4 blockade phenocopying this defect — establishing SAP/2B4 as directors of lytic synapse formation against EBV-positive targets.","evidence":"XLP patient CTL cytotoxicity, immunofluorescence of immunological synapse, 2B4 antibody blockade","pmids":["15677558"],"confidence":"High","gaps":["Whether NTB-A cooperates with 2B4 at the lytic synapse was not resolved","The signaling cascade linking SAP/2B4 to cytoskeletal polarization machinery was unknown"]},{"year":2008,"claim":"Identification of NCK1 as a novel SAP SH2-domain partner competing with FynT for the same non-canonical surface expanded the adaptor network through which SAP modulates TCR-proximal signaling (LAT, SLP-76, ERK pathway).","evidence":"SH3 domain panel screen, NMR binding, siRNA knockdown with phospho-signaling readouts","pmids":["18951976"],"confidence":"Medium","gaps":["Relative in vivo contribution of NCK1 vs. FynT binding to SAP function was unclear","Whether NCK1–SAP interaction operates in NK cells or only in T cells was untested"]},{"year":2009,"claim":"SAP and NTB-A were shown to cooperate in promoting TCR restimulation-induced cell death (RICD), with SAP progressively displacing SHP-1 from NTB-A to amplify TCR signal strength above the apoptotic threshold — explaining why SAP-deficient T cells resist RICD and accumulate during viral infections.","evidence":"XLP patient T cells, siRNA knockdown, antibody blockade, co-immunoprecipitation time-course, apoptosis assays","pmids":["19759517"],"confidence":"High","gaps":["Downstream effector pathway linking amplified TCR signaling to the apoptotic program was not delineated","Whether other SLAM-family receptors contribute to RICD was untested"]},{"year":2011,"claim":"Natural chimera analysis in female XLP carriers demonstrated that SLAM-family receptors (NTB-A, 2B4) on B cells actively inhibit SAP-negative CTLs — proving that EBV susceptibility in XLP reflects inhibitory SLAM signaling against B cell targets, not a virus-specific defect.","evidence":"X-inactivation mosaicism in XLP carriers, SLAM receptor blockade restoring SAP− CTL killing, ectopic NTB-A on fibroblasts","pmids":["22069374"],"confidence":"High","gaps":["Whether therapeutic SLAM receptor blockade could benefit XLP patients was not tested clinically","Contribution of each individual SLAM-family receptor to inhibitory signaling was not quantified"]},{"year":2016,"claim":"Mechanistic dissection revealed that SAP promotes RICD by enabling TCR-induced inhibition of diacylglycerol kinase α (DGKα), sustaining DAG–Ras–PKCθ signaling; pharmacological DGKα inhibition rescued RICD in SAP-deficient cells and prevented lethal CD8+ T cell expansion in SAP-deficient mice after LCMV infection — identifying a druggable node downstream of SAP.","evidence":"XLP patient T cells, DGKα inhibitors/genetic approaches, LCMV infection in Sh2d1a−/− mice, immune synapse imaging","pmids":["26764158"],"confidence":"High","gaps":["How SAP mechanistically suppresses DGKα enzymatic activity was not defined","Clinical translation of DGKα inhibition in XLP patients has not been tested","Whether DGKα inhibition also rescues germinal center or NKT cell defects in SAP deficiency is unknown"]},{"year":null,"claim":"The precise mechanism by which SAP controls NKT cell development, the SLAM-family receptor(s) mediating this checkpoint, the structural basis for SAP-dependent DGKα regulation, and whether therapeutic targeting of DGKα or SLAM receptors can benefit XLP patients remain unresolved.","evidence":"","pmids":[],"confidence":"High","gaps":["Stage-specific SLAM-family receptor requirement for NKT cell selection is undefined","Molecular mechanism linking SAP to DGKα suppression is unknown","No clinical trial data exist for DGKα inhibition or SLAM receptor blockade in XLP"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,3,6,9,21]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,5,17,20]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[0,3]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[3,17,19]}],"pathway":[{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[0,3,4,10,15,16,18,25]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[3,5,9,14,21,26]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[17,26]}],"complexes":["SLAM-SAP-FynT ternary complex"],"partners":["SLAMF1","CD244","SLAMF6","CD84","LY9","FYN","NCK1","PTPN6"],"other_free_text":[]},"mechanistic_narrative":"SH2D1A encodes SAP, a small lymphocyte-specific adaptor protein composed almost entirely of a single SH2 domain that serves as a master regulator of SLAM-family receptor signaling in T, NK, and NKT cells. SAP binds the immunoreceptor tyrosine-based switch motifs (ITSMs) of SLAM-family receptors (SLAM/CD150, 2B4/CD244, NTB-A, CD84, Ly-9) via a unique three-pronged mechanism that recognizes both phosphorylated and non-phosphorylated TIpYXX(V/I) peptides, simultaneously blocking recruitment of the inhibitory phosphatases SHP-1/SHP-2 and recruiting the Src-family kinase FynT through a non-canonical SH2–SH3 surface interaction that promotes kinase activation [PMID:9774102, PMID:10549287, PMID:11477403, PMID:12545174]. This dual adaptor/inhibitor function is essential for NKT cell development, germinal center formation, T-dependent humoral immunity, NK/CTL cytotoxicity against EBV-infected B cells, and TCR restimulation-induced cell death (RICD), with RICD requiring SAP-dependent suppression of diacylglycerol kinase α to sustain DAG-Ras signaling [PMID:15711562, PMID:15774582, PMID:15677558, PMID:19759517, PMID:26764158]. Loss-of-function mutations in SH2D1A cause X-linked lymphoproliferative disease (XLP), in which SLAM-family receptors acquire inappropriate inhibitory signaling due to unopposed SHP recruitment, leading to fatal EBV-driven immunopathology, dysgammaglobulinemia, and lymphoma [PMID:9774102, PMID:22069374]."},"prefetch_data":{"uniprot":{"accession":"O60880","full_name":"SH2 domain-containing protein 1A","aliases":["Duncan disease SH2-protein","Signaling lymphocytic activation molecule-associated protein","SLAM-associated protein","T-cell signal transduction molecule SAP"],"length_aa":128,"mass_kda":14.2,"function":"Cytoplasmic adapter regulating receptors of the signaling lymphocytic activation molecule (SLAM) family such as SLAMF1, CD244, LY9, CD84, SLAMF6 and SLAMF7. In SLAM signaling seems to cooperate with SH2D1B/EAT-2. Initially it has been proposed that association with SLAMF1 prevents SLAMF1 binding to inhibitory effectors including INPP5D/SHIP1 and PTPN11/SHP-2 (PubMed:11806999). However, by simultaneous interactions, recruits FYN which subsequently phosphorylates and activates SLAMF1 (PubMed:12458214). Positively regulates CD244/2B4- and CD84-mediated natural killer (NK) cell functions. Can also promote CD48-, SLAMF6 -, LY9-, and SLAMF7-mediated NK cell activation. In the context of NK cell-mediated cytotoxicity enhances conjugate formation with target cells (By similarity). May also regulate the activity of the neurotrophin receptors NTRK1, NTRK2 and NTRK3","subcellular_location":"Cytoplasm","url":"https://www.uniprot.org/uniprotkb/O60880/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/SH2D1A","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/SH2D1A","total_profiled":1310},"omim":[{"mim_id":"615122","title":"LYMPHOPROLIFERATIVE SYNDROME 2; LPFS2","url":"https://www.omim.org/entry/615122"},{"mim_id":"606784","title":"GLYCOGEN SYNTHASE KINASE 3-ALPHA; GSK3A","url":"https://www.omim.org/entry/606784"},{"mim_id":"606446","title":"SLAM FAMILY, MEMBER 6; SLAMF6","url":"https://www.omim.org/entry/606446"},{"mim_id":"605554","title":"CD244 ANTIGEN; CD244","url":"https://www.omim.org/entry/605554"},{"mim_id":"605004","title":"GLYCOGEN SYNTHASE KINASE 3-BETA; GSK3B","url":"https://www.omim.org/entry/605004"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Cytosol","reliability":"Approved"}],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in some","driving_tissues":[{"tissue":"lymphoid tissue","ntpm":200.5}],"url":"https://www.proteinatlas.org/search/SH2D1A"},"hgnc":{"alias_symbol":["XLP","MTCP1","DSHP","XLPD","EBVS","SAP"],"prev_symbol":["IMD5","LYP"]},"alphafold":{"accession":"O60880","domains":[{"cath_id":"3.30.505.10","chopping":"6-100","consensus_level":"high","plddt":92.1523,"start":6,"end":100}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O60880","model_url":"https://alphafold.ebi.ac.uk/files/AF-O60880-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O60880-F1-predicted_aligned_error_v6.png","plddt_mean":83.69},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=SH2D1A","jax_strain_url":"https://www.jax.org/strain/search?query=SH2D1A"},"sequence":{"accession":"O60880","fasta_url":"https://rest.uniprot.org/uniprotkb/O60880.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O60880/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O60880"}},"corpus_meta":[{"pmid":"15711562","id":"PMC_15711562","title":"Regulation of NKT cell development by SAP, the protein defective in XLP.","date":"2005","source":"Nature medicine","url":"https://pubmed.ncbi.nlm.nih.gov/15711562","citation_count":301,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"21119115","id":"PMC_21119115","title":"Clinical similarities and differences of patients with X-linked lymphoproliferative syndrome type 1 (XLP-1/SAP deficiency) versus type 2 (XLP-2/XIAP deficiency).","date":"2010","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/21119115","citation_count":265,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"11489943","id":"PMC_11489943","title":"NTB-A [correction of GNTB-A], a novel SH2D1A-associated surface molecule contributing to the inability of natural killer cells to kill Epstein-Barr virus-infected B cells in X-linked lymphoproliferative disease.","date":"2001","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/11489943","citation_count":256,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"20926771","id":"PMC_20926771","title":"X-linked lymphoproliferative disease due to SAP/SH2D1A deficiency: a multicenter study on the manifestations, management and outcome of the disease.","date":"2010","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/20926771","citation_count":215,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"11404475","id":"PMC_11404475","title":"Altered lymphocyte responses and cytokine production in mice deficient in the X-linked lymphoproliferative disease gene SH2D1A/DSHP/SAP.","date":"2001","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/11404475","citation_count":210,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"10549287","id":"PMC_10549287","title":"Crystal structures of the XLP protein SAP reveal a class of SH2 domains with extended, phosphotyrosine-independent sequence recognition.","date":"1999","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/10549287","citation_count":202,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"11049992","id":"PMC_11049992","title":"Correlation of mutations of the SH2D1A gene and epstein-barr virus infection with clinical phenotype and outcome in X-linked lymphoproliferative disease.","date":"2000","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/11049992","citation_count":190,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"11313386","id":"PMC_11313386","title":"CD150 association with either the SH2-containing inositol phosphatase or the SH2-containing protein tyrosine phosphatase is regulated by the adaptor protein SH2D1A.","date":"2001","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/11313386","citation_count":169,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"17853891","id":"PMC_17853891","title":"The coupling of synthesis and partitioning of EBV's plasmid replicon is revealed in live cells.","date":"2007","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/17853891","citation_count":165,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"6283885","id":"PMC_6283885","title":"Epstein-Barr virus-induced diseases in boys with the X-linked lymphoproliferative syndrome (XLP): update on studies of the registry.","date":"1982","source":"The American journal of medicine","url":"https://pubmed.ncbi.nlm.nih.gov/6283885","citation_count":160,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"8361760","id":"PMC_8361760","title":"MTCP-1: a novel gene on the human chromosome Xq28 translocated to the T cell receptor alpha/delta locus in mature T cell proliferations.","date":"1993","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/8361760","citation_count":138,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"11159547","id":"PMC_11159547","title":"Hemophagocytic lymphohistiocytosis due to germline mutations in SH2D1A, the X-linked lymphoproliferative disease gene.","date":"2001","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/11159547","citation_count":118,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"16966603","id":"PMC_16966603","title":"Transcriptional activation by EBV nuclear antigen 1 is essential for the expression of EBV's transforming genes.","date":"2006","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/16966603","citation_count":115,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"35415952","id":"PMC_35415952","title":"Global genetic diversity status and trends: towards a suite of Essential Biodiversity Variables (EBVs) for genetic composition.","date":"2022","source":"Biological reviews of the Cambridge Philosophical Society","url":"https://pubmed.ncbi.nlm.nih.gov/35415952","citation_count":103,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"25085526","id":"PMC_25085526","title":"XLP: clinical features and molecular etiology due to mutations in SH2D1A encoding SAP.","date":"2014","source":"Journal of clinical immunology","url":"https://pubmed.ncbi.nlm.nih.gov/25085526","citation_count":98,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"22069374","id":"PMC_22069374","title":"Molecular pathogenesis of EBV susceptibility in XLP as revealed by analysis of female carriers with heterozygous expression of SAP.","date":"2011","source":"PLoS biology","url":"https://pubmed.ncbi.nlm.nih.gov/22069374","citation_count":98,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"10607564","id":"PMC_10607564","title":"Novel mode of ligand binding by the SH2 domain of the human XLP disease gene product SAP/SH2D1A.","date":"1999","source":"Current biology : CB","url":"https://pubmed.ncbi.nlm.nih.gov/10607564","citation_count":94,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"11520777","id":"PMC_11520777","title":"Alterations of the X-linked lymphoproliferative disease gene SH2D1A in common variable immunodeficiency syndrome.","date":"2001","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/11520777","citation_count":93,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"15263031","id":"PMC_15263031","title":"SH2D1A regulates T-dependent humoral autoimmunity.","date":"2004","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/15263031","citation_count":85,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"28766908","id":"PMC_28766908","title":"Building essential biodiversity variables (EBVs) of species distribution and abundance at a global scale.","date":"2017","source":"Biological reviews of the Cambridge Philosophical Society","url":"https://pubmed.ncbi.nlm.nih.gov/28766908","citation_count":82,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"11823424","id":"PMC_11823424","title":"A \"three-pronged\" binding mechanism for the SAP/SH2D1A SH2 domain: structural basis and relevance to the XLP syndrome.","date":"2002","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/11823424","citation_count":80,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"10556288","id":"PMC_10556288","title":"Epstein-Barr virus-negative boys with non-Hodgkin lymphoma are mutated in the SH2D1A gene, as are patients with X-linked lymphoproliferative disease (XLP).","date":"1999","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/10556288","citation_count":76,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"11477068","id":"PMC_11477068","title":"Characterization of SH2D1A missense mutations identified in X-linked lymphoproliferative disease patients.","date":"2001","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/11477068","citation_count":71,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"12458214","id":"PMC_12458214","title":"Dual functional roles for the X-linked lymphoproliferative syndrome gene product SAP/SH2D1A in signaling through the signaling lymphocyte activation molecule (SLAM) family of immune receptors.","date":"2002","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12458214","citation_count":70,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"9657733","id":"PMC_9657733","title":"Transgenic mice for MTCP1 develop T-cell prolymphocytic leukemia.","date":"1998","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/9657733","citation_count":68,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"15774582","id":"PMC_15774582","title":"Defective B cell responses in the absence of SH2D1A.","date":"2005","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/15774582","citation_count":56,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"15632210","id":"PMC_15632210","title":"Rapid detection of intracellular SH2D1A protein in cytotoxic lymphocytes from patients with X-linked lymphoproliferative disease and their family members.","date":"2005","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/15632210","citation_count":50,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"8733691","id":"PMC_8733691","title":"Cure of X-linked lymphoproliferative disease (XLP) with allogeneic hematopoietic stem cell transplantation (HSCT): report from the XLP registry.","date":"1996","source":"Bone marrow transplantation","url":"https://pubmed.ncbi.nlm.nih.gov/8733691","citation_count":49,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"10852966","id":"PMC_10852966","title":"The X-linked lymphoproliferative syndrome gene product SH2D1A associates with p62dok (Dok1) and activates NF-kappa B.","date":"2000","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/10852966","citation_count":46,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"14604960","id":"PMC_14604960","title":"Loss of circulating CD27+ memory B cells and CCR4+ T cells occurring in association with elevated EBV loads in XLP patients surviving primary EBV infection.","date":"2003","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/14604960","citation_count":44,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"26764158","id":"PMC_26764158","title":"Inhibition of diacylglycerol kinase α restores restimulation-induced cell death and reduces immunopathology in XLP-1.","date":"2016","source":"Science translational medicine","url":"https://pubmed.ncbi.nlm.nih.gov/26764158","citation_count":44,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"11493483","id":"PMC_11493483","title":"SH2D1A mutations in Japanese males with severe Epstein-Barr virus--associated illnesses.","date":"2001","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/11493483","citation_count":43,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"1972651","id":"PMC_1972651","title":"Partial Xq25 deletion in a family with the X-linked lymphoproliferative disease (XLP).","date":"1990","source":"Cancer genetics and cytogenetics","url":"https://pubmed.ncbi.nlm.nih.gov/1972651","citation_count":40,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"16788096","id":"PMC_16788096","title":"Hypogammaglobulinemia and exacerbated CD8 T-cell-mediated immunopathology in SAP-deficient mice with chronic LCMV infection mimics human XLP disease.","date":"2006","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/16788096","citation_count":38,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"29665027","id":"PMC_29665027","title":"Genetic variant spectrum in 265 Chinese patients with hemophagocytic lymphohistiocytosis: Molecular analyses of PRF1, UNC13D, STX11, STXBP2, SH2D1A, and XIAP.","date":"2018","source":"Clinical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/29665027","citation_count":38,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"21674762","id":"PMC_21674762","title":"Screening the PRF1, UNC13D, STX11, SH2D1A, XIAP, and ITK gene mutations in Chinese children with Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis.","date":"2011","source":"Pediatric blood & cancer","url":"https://pubmed.ncbi.nlm.nih.gov/21674762","citation_count":36,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"11815622","id":"PMC_11815622","title":"Association of the X-linked lymphoproliferative disease gene product SAP/SH2D1A with 2B4, a natural killer cell-activating molecule, is dependent on phosphoinositide 3-kinase.","date":"2002","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/11815622","citation_count":35,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"9520380","id":"PMC_9520380","title":"Crystal structure of MTCP-1: implications for role of TCL-1 and MTCP-1 in T cell malignancies.","date":"1998","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/9520380","citation_count":33,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"8570215","id":"PMC_8570215","title":"Expression of either the TCL1 oncogene, or transcripts from its homologue MTCP1/c6.1B, in leukaemic and non-leukaemic T cells from ataxia telangiectasia patients.","date":"1996","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/8570215","citation_count":33,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"19628040","id":"PMC_19628040","title":"Proof for EBV's sustaining role in Burkitt's lymphomas.","date":"2009","source":"Seminars in cancer biology","url":"https://pubmed.ncbi.nlm.nih.gov/19628040","citation_count":32,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"15315965","id":"PMC_15315965","title":"The adaptor protein SH2D1A regulates signaling through CD150 (SLAM) in B cells.","date":"2004","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/15315965","citation_count":31,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"10598819","id":"PMC_10598819","title":"SH2D1A mutation analysis for diagnosis of XLP in typical and atypical patients.","date":"1999","source":"Human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/10598819","citation_count":31,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"12152986","id":"PMC_12152986","title":"A spectrum of mutations in SH2D1A that causes X-linked lymphoproliferative disease and other Epstein-Barr virus-associated illnesses.","date":"2002","source":"Leukemia & lymphoma","url":"https://pubmed.ncbi.nlm.nih.gov/12152986","citation_count":30,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"18951976","id":"PMC_18951976","title":"The XLP syndrome protein SAP interacts with SH3 proteins to regulate T cell signaling and proliferation.","date":"2008","source":"Cellular signalling","url":"https://pubmed.ncbi.nlm.nih.gov/18951976","citation_count":30,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"7784073","id":"PMC_7784073","title":"The 8 kD product of the putative oncogene MTCP-1 is a mitochondrial protein.","date":"1995","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/7784073","citation_count":28,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"12115526","id":"PMC_12115526","title":"SH2D1A expression in Burkitt lymphoma cells is restricted to EBV positive group I lines and is downregulated in parallel with immunoblastic transformation.","date":"2002","source":"International journal of cancer","url":"https://pubmed.ncbi.nlm.nih.gov/12115526","citation_count":27,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"12447665","id":"PMC_12447665","title":"Mutations of the X-linked lymphoproliferative disease gene SH2D1A mimicking common variable immunodeficiency.","date":"2002","source":"European journal of pediatrics","url":"https://pubmed.ncbi.nlm.nih.gov/12447665","citation_count":26,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"24616127","id":"PMC_24616127","title":"Clinical flow cytometric screening of SAP and XIAP expression accurately identifies patients with SH2D1A and XIAP/BIRC4 mutations.","date":"2014","source":"Cytometry. Part B, Clinical cytometry","url":"https://pubmed.ncbi.nlm.nih.gov/24616127","citation_count":26,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"30611057","id":"PMC_30611057","title":"Identification of a novel DGKα inhibitor for XLP-1 therapy by virtual screening.","date":"2018","source":"European journal of medicinal chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/30611057","citation_count":24,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"26339045","id":"PMC_26339045","title":"Epstein-Barr Viruses (EBVs) Deficient in EBV-Encoded RNAs Have Higher Levels of Latent Membrane Protein 2 RNA Expression in Lymphoblastoid Cell Lines and Efficiently Establish Persistent Infections in Humanized Mice.","date":"2015","source":"Journal of virology","url":"https://pubmed.ncbi.nlm.nih.gov/26339045","citation_count":24,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"12894850","id":"PMC_12894850","title":"Identification of an SH2D1A mutation in a hypogammaglobulinemic male patient with a diagnosis of common variable immunodeficiency.","date":"2003","source":"International journal of hematology","url":"https://pubmed.ncbi.nlm.nih.gov/12894850","citation_count":23,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"19595300","id":"PMC_19595300","title":"Phenotypic differences between mice deficient in XIAP and SAP, two factors targeted in X-linked lymphoproliferative syndrome (XLP).","date":"2009","source":"Cellular immunology","url":"https://pubmed.ncbi.nlm.nih.gov/19595300","citation_count":23,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"12594824","id":"PMC_12594824","title":"Expression of SH2D1A in five classical Hodgkin's disease-derived cell lines.","date":"2003","source":"International journal of cancer","url":"https://pubmed.ncbi.nlm.nih.gov/12594824","citation_count":22,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"23589280","id":"PMC_23589280","title":"Frequent mutations in SH2D1A (XLP) in males presenting with high-grade mature B-cell neoplasms.","date":"2013","source":"Pediatric blood & cancer","url":"https://pubmed.ncbi.nlm.nih.gov/23589280","citation_count":21,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"18815745","id":"PMC_18815745","title":"X-linked lymphoproliferative disease (XLP): a model of impaired anti-viral, anti-tumor and humoral immune responses.","date":"2008","source":"Immunologic research","url":"https://pubmed.ncbi.nlm.nih.gov/18815745","citation_count":21,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"9405159","id":"PMC_9405159","title":"Solution structure of human p8MTCP1, a cysteine-rich protein encoded by the MTCP1 oncogene, reveals a new alpha-helical assembly motif.","date":"1997","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/9405159","citation_count":21,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"26305518","id":"PMC_26305518","title":"Clinical Flow Cytometric Screening of SAP and XIAP Expression Accurately Identifies Patients with SH2D1A and XIAP/BIRC4 Mutations.","date":"2014","source":"Cytometry. Part B, Clinical cytometry","url":"https://pubmed.ncbi.nlm.nih.gov/26305518","citation_count":21,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"11545600","id":"PMC_11545600","title":"Characterization of the folding and unfolding reactions of a small beta-barrel protein of novel topology, the MTCP1 oncogene product P13.","date":"2001","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/11545600","citation_count":20,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"10344735","id":"PMC_10344735","title":"Identification of the TCL1/MTCP1-like 1 (TML1) gene from the region next to the TCL1 locus.","date":"1999","source":"Cancer research","url":"https://pubmed.ncbi.nlm.nih.gov/10344735","citation_count":20,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"35677600","id":"PMC_35677600","title":"Genome Editing With TALEN, CRISPR-Cas9 and CRISPR-Cas12a in Combination With AAV6 Homology Donor Restores T Cell Function for XLP.","date":"2022","source":"Frontiers in genome editing","url":"https://pubmed.ncbi.nlm.nih.gov/35677600","citation_count":19,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"10694488","id":"PMC_10694488","title":"Structural basis for SH2D1A mutations in X-linked lymphoproliferative disease.","date":"2000","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/10694488","citation_count":19,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"9027486","id":"PMC_9027486","title":"A yeast artificial chromosome (YAC) contig encompassing the critical region of the X-linked lymphoproliferative disease (XLP) locus.","date":"1997","source":"Genomics","url":"https://pubmed.ncbi.nlm.nih.gov/9027486","citation_count":19,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"9758353","id":"PMC_9758353","title":"Matched unrelated allogeneic bone marrow transplantation for recurrent malignant lymphoma in a patient with X-linked lymphoproliferative disease (XLP).","date":"1998","source":"Bone marrow transplantation","url":"https://pubmed.ncbi.nlm.nih.gov/9758353","citation_count":19,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"31231620","id":"PMC_31231620","title":"Systemic Epstein-Barr Virus-Positive T/NK Lymphoproliferative Diseases With SH2D1A/XIAP Hypomorphic Gene Variants.","date":"2019","source":"Frontiers in pediatrics","url":"https://pubmed.ncbi.nlm.nih.gov/31231620","citation_count":18,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"8406447","id":"PMC_8406447","title":"High-resolution mapping of probes near the X-linked lymphoproliferative disease (XLP) locus.","date":"1993","source":"Genomics","url":"https://pubmed.ncbi.nlm.nih.gov/8406447","citation_count":18,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"25795023","id":"PMC_25795023","title":"Complete genome sequence of vB_DshP-R2C, a N4-like lytic roseophage.","date":"2015","source":"Marine genomics","url":"https://pubmed.ncbi.nlm.nih.gov/25795023","citation_count":17,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"20632414","id":"PMC_20632414","title":"Early and rapid detection of X-linked lymphoproliferative syndrome with SH2D1A mutations by flow cytometry.","date":"2011","source":"Cytometry. Part B, Clinical cytometry","url":"https://pubmed.ncbi.nlm.nih.gov/20632414","citation_count":15,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"15841490","id":"PMC_15841490","title":"Characterization of a new disease-causing mutation of SH2D1A in a family with X-linked lymphoproliferative disease.","date":"2005","source":"Human mutation","url":"https://pubmed.ncbi.nlm.nih.gov/15841490","citation_count":15,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"11054065","id":"PMC_11054065","title":"T-cell prolymphocytic leukaemia: antigen receptor gene rearrangement and a novel mode of MTCP1 B1 activation.","date":"2000","source":"British journal of haematology","url":"https://pubmed.ncbi.nlm.nih.gov/11054065","citation_count":15,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"28259048","id":"PMC_28259048","title":"Dissecting the regulation of EBV's BART miRNAs in carcinomas.","date":"2017","source":"Virology","url":"https://pubmed.ncbi.nlm.nih.gov/28259048","citation_count":15,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"15459902","id":"PMC_15459902","title":"Expression of the SH2D1A gene is regulated by a combination of transcriptional and post-transcriptional mechanisms.","date":"2004","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/15459902","citation_count":14,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"11536244","id":"PMC_11536244","title":"No mutations of SAP/SH2D1A/DSHP and perforin genes in patients with Epstein-Barr virus-associated hemophagocytic syndrome in Japan.","date":"2001","source":"Journal of medical virology","url":"https://pubmed.ncbi.nlm.nih.gov/11536244","citation_count":13,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"16720617","id":"PMC_16720617","title":"Missense mutations in SH2D1A identified in patients with X-linked lymphoproliferative disease differentially affect the expression and function of SAP.","date":"2006","source":"International immunology","url":"https://pubmed.ncbi.nlm.nih.gov/16720617","citation_count":13,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"12224001","id":"PMC_12224001","title":"Analysis of SH2D1A mutations in patients with severe Epstein-Barr virus infections, Burkitt's lymphoma, and Hodgkin's lymphoma.","date":"2002","source":"Annals of hematology","url":"https://pubmed.ncbi.nlm.nih.gov/12224001","citation_count":13,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"37858067","id":"PMC_37858067","title":"Overexpression of SH2D1A promotes cancer progression and is associated with immune cell infiltration in hepatocellular carcinoma via bioinformatics and in vitro study.","date":"2023","source":"BMC cancer","url":"https://pubmed.ncbi.nlm.nih.gov/37858067","citation_count":11,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"22258354","id":"PMC_22258354","title":"HHV-8-related hemophagocytic lymphohistiocytosis in a boy with XLP phenotype.","date":"2012","source":"Journal of pediatric hematology/oncology","url":"https://pubmed.ncbi.nlm.nih.gov/22258354","citation_count":11,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"30849948","id":"PMC_30849948","title":"Rare cause of Hemophagocytic Lymphohistiocytosis due to mutation in PRF1 and SH2D1A genes in two children - a case report with a review.","date":"2019","source":"BMC pediatrics","url":"https://pubmed.ncbi.nlm.nih.gov/30849948","citation_count":10,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"30572125","id":"PMC_30572125","title":"Management of XLP-1 and ITK deficiency: The challenges posed by PID with an unpredictable spectrum of disease manifestations.","date":"2018","source":"Clinical immunology (Orlando, Fla.)","url":"https://pubmed.ncbi.nlm.nih.gov/30572125","citation_count":10,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"11803050","id":"PMC_11803050","title":"SH2D1A expression reflects activation of T and NK cells in cord blood lymphocytes infected with EBV and treated with the immunomodulator PSK.","date":"2002","source":"Immunology letters","url":"https://pubmed.ncbi.nlm.nih.gov/11803050","citation_count":10,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"15812353","id":"PMC_15812353","title":"The role of CD150-SH2D1A association in CD150 signaling in Hodgkin's lymphoma cell lines.","date":"2005","source":"Experimental oncology","url":"https://pubmed.ncbi.nlm.nih.gov/15812353","citation_count":9,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"9801876","id":"PMC_9801876","title":"A new candidate region for the positional cloning of the XLP gene.","date":"1998","source":"European journal of human genetics : EJHG","url":"https://pubmed.ncbi.nlm.nih.gov/9801876","citation_count":9,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"23554038","id":"PMC_23554038","title":"Association of a single nucleotide polymorphism in the SH2D1A intronic region with systemic lupus erythematosus.","date":"2013","source":"Lupus","url":"https://pubmed.ncbi.nlm.nih.gov/23554038","citation_count":9,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"22271700","id":"PMC_22271700","title":"Skin lesions in a boy with X-linked lymphoproliferative disorder: comparison of 5 SH2D1A deletion cases.","date":"2012","source":"Pediatrics","url":"https://pubmed.ncbi.nlm.nih.gov/22271700","citation_count":9,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"21996454","id":"PMC_21996454","title":"CD4+ T Lymphocytes with follicular helper phenotype (T(FH)) in patients with SH2D1A deficiency (XLP).","date":"2011","source":"Clinical immunology (Orlando, Fla.)","url":"https://pubmed.ncbi.nlm.nih.gov/21996454","citation_count":8,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"12709835","id":"PMC_12709835","title":"Differential methylation pattern of the X-linked lymphoproliferative (XLP) disease gene SH2D1A correlates with the cell lineage-specific transcription.","date":"2003","source":"Immunogenetics","url":"https://pubmed.ncbi.nlm.nih.gov/12709835","citation_count":8,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"34732719","id":"PMC_34732719","title":"Rare t(X;14)(q28;q32) translocation reveals link between MTCP1 and chronic lymphocytic leukemia.","date":"2021","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/34732719","citation_count":7,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"30233082","id":"PMC_30233082","title":"miR-126 Suppresses Invasion and Migration of Malignant Glioma by Targeting Mature T Cell Proliferation 1 (MTCP1).","date":"2018","source":"Medical science monitor : international medical journal of experimental and clinical research","url":"https://pubmed.ncbi.nlm.nih.gov/30233082","citation_count":6,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"12395426","id":"PMC_12395426","title":"Helix motion in protein C12A-p8(MTCP1): comparison of molecular dynamics simulations and multifield NMR relaxation data.","date":"2002","source":"Journal of computational chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12395426","citation_count":6,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"28267077","id":"PMC_28267077","title":"Novel Mutations in SH2D1A Gene in X-linked Lymphoproliferative Syndrome, Diagnosed After B-Cell Non-Hodgkin Lymphoma.","date":"2017","source":"Journal of pediatric hematology/oncology","url":"https://pubmed.ncbi.nlm.nih.gov/28267077","citation_count":6,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"31994322","id":"PMC_31994322","title":"Diagnostic challenges for a novel SH2D1A mutation associated with X-linked lymphoproliferative disease.","date":"2020","source":"Pediatric blood & cancer","url":"https://pubmed.ncbi.nlm.nih.gov/31994322","citation_count":6,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"9518463","id":"PMC_9518463","title":"Purification and characterization of recombinant forms of TCL-1 and MTCP-1 proteins.","date":"1998","source":"Protein expression and purification","url":"https://pubmed.ncbi.nlm.nih.gov/9518463","citation_count":6,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"25982576","id":"PMC_25982576","title":"Study of SH2D1A gene mutation in paediatric patients with B-cell lymphoma.","date":"2015","source":"Allergologia et immunopathologia","url":"https://pubmed.ncbi.nlm.nih.gov/25982576","citation_count":6,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"17302894","id":"PMC_17302894","title":"Factors involved in the generation of memory CD8+ T cells in patients with X-linked lymphoproliferative disease (XLP).","date":"2007","source":"Clinical and experimental immunology","url":"https://pubmed.ncbi.nlm.nih.gov/17302894","citation_count":6,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"8256804","id":"PMC_8256804","title":"Evaluation of families wherein a single male manifests a phenotype of X-linked lymphoproliferative disease (XLP).","date":"1993","source":"American journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/8256804","citation_count":6,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"24723092","id":"PMC_24723092","title":"The value of DNA storage and pedigree analysis in rare diseases: a 17-year-old boy with X-linked lymphoproliferative disease (XLP) caused by a de novo SH2D1A mutation.","date":"2014","source":"European journal of pediatrics","url":"https://pubmed.ncbi.nlm.nih.gov/24723092","citation_count":6,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"22425739","id":"PMC_22425739","title":"The -346T polymorphism of the SH2D1A gene is a risk factor for development of autoimmunity/lymphoproliferation in males with defective Fas function.","date":"2012","source":"Human immunology","url":"https://pubmed.ncbi.nlm.nih.gov/22425739","citation_count":5,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"25572984","id":"PMC_25572984","title":"Maternal onset de novo SH2D1A mutation and lymphocytic choriomeningitis virus infection in a patient with X‑linked lymphoproliferative disease type 1: a case report.","date":"2015","source":"Molecular medicine reports","url":"https://pubmed.ncbi.nlm.nih.gov/25572984","citation_count":5,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"21541208","id":"PMC_21541208","title":"X-Linked Lymphoproliferative Syndrome and Common Variable Immunodeficiency May Not Be Differentiated by SH2D1A and XIAP/BIRC4 Genes Sequence Analysis.","date":"2011","source":"Case reports in medicine","url":"https://pubmed.ncbi.nlm.nih.gov/21541208","citation_count":5,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"3030340","id":"PMC_3030340","title":"Epstein-Barr virus (EBV) and X-linked lymphoproliferative syndrome (XLP).","date":"1986","source":"AIDS research","url":"https://pubmed.ncbi.nlm.nih.gov/3030340","citation_count":5,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"28231257","id":"PMC_28231257","title":"Targeted sequencing identifies a novel SH2D1A pathogenic variant in a Chinese family: Carrier screening and prenatal genetic testing.","date":"2017","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/28231257","citation_count":5,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"12477932","id":"PMC_12477932","title":"Generation and initial analysis of more than 15,000 full-length human and mouse cDNA sequences.","date":"2002","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/12477932","citation_count":1479,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"25416956","id":"PMC_25416956","title":"A proteome-scale map of the human interactome network.","date":"2014","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/25416956","citation_count":977,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"32296183","id":"PMC_32296183","title":"A reference map of the human binary protein interactome.","date":"2020","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/32296183","citation_count":849,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"15772651","id":"PMC_15772651","title":"The DNA sequence of the human X chromosome.","date":"2005","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/15772651","citation_count":816,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"9774102","id":"PMC_9774102","title":"The X-linked lymphoproliferative-disease gene product SAP regulates signals induced through the co-receptor SLAM.","date":"1998","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/9774102","citation_count":706,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"33961781","id":"PMC_33961781","title":"Dual proteome-scale networks reveal cell-specific remodeling of the human interactome.","date":"2021","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/33961781","citation_count":705,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"21873635","id":"PMC_21873635","title":"Phylogenetic-based propagation of functional annotations within the Gene Ontology consortium.","date":"2011","source":"Briefings in bioinformatics","url":"https://pubmed.ncbi.nlm.nih.gov/21873635","citation_count":656,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"9771704","id":"PMC_9771704","title":"Host response to EBV infection in X-linked lymphoproliferative disease results from mutations in an SH2-domain encoding gene.","date":"1998","source":"Nature genetics","url":"https://pubmed.ncbi.nlm.nih.gov/9771704","citation_count":577,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"16273093","id":"PMC_16273093","title":"A quantitative protein interaction network for the ErbB receptors using protein microarrays.","date":"2005","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/16273093","citation_count":568,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"25910212","id":"PMC_25910212","title":"Widespread macromolecular interaction perturbations in human genetic disorders.","date":"2015","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/25910212","citation_count":454,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"15489334","id":"PMC_15489334","title":"The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC).","date":"2004","source":"Genome research","url":"https://pubmed.ncbi.nlm.nih.gov/15489334","citation_count":438,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"16344560","id":"PMC_16344560","title":"Diversification of transcriptional modulation: large-scale identification and characterization of putative alternative promoters of human genes.","date":"2005","source":"Genome research","url":"https://pubmed.ncbi.nlm.nih.gov/16344560","citation_count":409,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"9811875","id":"PMC_9811875","title":"Inactivating mutations in an SH2 domain-encoding gene in X-linked lymphoproliferative syndrome.","date":"1998","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/9811875","citation_count":406,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"15738056","id":"PMC_15738056","title":"Defective NKT cell development in mice and humans lacking the adapter SAP, the X-linked lymphoproliferative syndrome gene product.","date":"2005","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/15738056","citation_count":269,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"12545174","id":"PMC_12545174","title":"SAP couples Fyn to SLAM immune receptors.","date":"2003","source":"Nature cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/12545174","citation_count":249,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"14523387","id":"PMC_14523387","title":"The SAP and SLAM families in immune responses and X-linked lymphoproliferative disease.","date":"2003","source":"Nature reviews. Immunology","url":"https://pubmed.ncbi.nlm.nih.gov/14523387","citation_count":233,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"10358138","id":"PMC_10358138","title":"Cutting edge: human 2B4, an activating NK cell receptor, recruits the protein tyrosine phosphatase SHP-2 and the adaptor signaling protein SAP.","date":"1999","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/10358138","citation_count":232,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"11477403","id":"PMC_11477403","title":"Regulation of SLAM-mediated signal transduction by SAP, the X-linked lymphoproliferative gene product.","date":"2001","source":"Nature immunology","url":"https://pubmed.ncbi.nlm.nih.gov/11477403","citation_count":205,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"9856458","id":"PMC_9856458","title":"Identification and characterization of novel substrates of Trk receptors in developing neurons.","date":"1998","source":"Neuron","url":"https://pubmed.ncbi.nlm.nih.gov/9856458","citation_count":191,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"19079134","id":"PMC_19079134","title":"SLAM receptors and SAP influence lymphocyte interactions, development and function.","date":"2009","source":"Nature reviews. Immunology","url":"https://pubmed.ncbi.nlm.nih.gov/19079134","citation_count":175,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"22438812","id":"PMC_22438812","title":"TGF-β1 down-regulation of NKG2D/DAP10 and 2B4/SAP expression on human NK cells contributes to HBV persistence.","date":"2012","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/22438812","citation_count":170,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"15713798","id":"PMC_15713798","title":"Molecular basis for positive and negative signaling by the natural killer cell receptor 2B4 (CD244).","date":"2005","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/15713798","citation_count":164,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"15677558","id":"PMC_15677558","title":"SAP controls the cytolytic activity of CD8+ T cells against EBV-infected cells.","date":"2005","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/15677558","citation_count":149,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"9235954","id":"PMC_9235954","title":"p38-2, a novel mitogen-activated protein kinase with distinct properties.","date":"1997","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/9235954","citation_count":148,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"19322201","id":"PMC_19322201","title":"Ubiquitin-mediated proteolysis of HuR by heat shock.","date":"2009","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/19322201","citation_count":142,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"19759517","id":"PMC_19759517","title":"Restimulation-induced apoptosis of T cells is impaired in patients with X-linked lymphoproliferative disease caused by SAP deficiency.","date":"2009","source":"The Journal of clinical investigation","url":"https://pubmed.ncbi.nlm.nih.gov/19759517","citation_count":134,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"11034354","id":"PMC_11034354","title":"Defective NK cell activation in X-linked lymphoproliferative disease.","date":"2000","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/11034354","citation_count":116,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"11389028","id":"PMC_11389028","title":"Cell surface receptors Ly-9 and CD84 recruit the X-linked lymphoproliferative disease gene product SAP.","date":"2001","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/11389028","citation_count":100,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"18031694","id":"PMC_18031694","title":"Consequence of the SLAM-SAP signaling pathway in innate-like and conventional lymphocytes.","date":"2007","source":"Immunity","url":"https://pubmed.ncbi.nlm.nih.gov/18031694","citation_count":100,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"15169881","id":"PMC_15169881","title":"Molecular dissection of 2B4 signaling: implications for signal transduction by SLAM-related receptors.","date":"2004","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/15169881","citation_count":86,"is_preprint":false,"source_track":"gene2pubmed"}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":47888,"output_tokens":5443,"usd":0.112655},"stage2":{"model":"claude-opus-4-6","input_tokens":9003,"output_tokens":2646,"usd":0.166747},"total_usd":0.664491,"stage1_batch_id":"msgbatch_011rkcQdVV1RaFq9XhcG6df6","stage2_batch_id":"msgbatch_01RzgrJafdF4EWHhj5mNi6dh","note":"batch pricing = 50% of standard","round2_stage1":{"model":"claude-sonnet-4-6","input_tokens":60231,"output_tokens":7172,"usd":0.144137},"round2_rules_fired":"R2","round2_stage2":{"model":"claude-opus-4-6","input_tokens":11137,"output_tokens":4198,"usd":0.240952}},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1999,\n      \"finding\": \"Crystal structures of SAP revealed that its SH2 domain binds both phosphorylated and nonphosphorylated SLAM peptides in a similar mode, with the tyrosine/phosphotyrosine inserted into the phosphotyrosine-binding pocket, and that specific interactions with residues N-terminal to the tyrosine (in addition to C-terminal interactions) stabilize the complexes. SAP and EAT-2 recognize the consensus motif TIpYXX(V/I).\",\n      \"method\": \"Crystal structure determination + phosphopeptide library screen + XLP patient mutation analysis\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structures with functional validation by peptide library and disease mutation analysis\",\n      \"pmids\": [\"10549287\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"NMR studies of SAP complexed with SLAM peptides demonstrated that the SAP SH2 domain binds peptides in a phosphorylation-independent manner and recognizes a pTyr residue either preceded by amino-terminal residues or followed by carboxy-terminal residues, engaging three 'prongs' of the peptide ligand simultaneously. Dissociation constants were ~150 nM (phosphopeptide) and ~330 nM (non-phosphopeptide).\",\n      \"method\": \"NMR spectroscopy with 15N/13C-labeled SAP + synthetic peptide binding assays\",\n      \"journal\": \"Current biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — NMR structural determination with quantitative binding measurements, consistent with independent crystal structure\",\n      \"pmids\": [\"10607564\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"NMR structures of the SAP/SH2D1A SH2 domain in complex with two distinct peptides provided direct evidence for a 'three-pronged' binding mechanism (N-terminal residues, pTyr, and C-terminal residues) distinct from conventional 'two-pronged' SH2 domain interactions. A consensus motif T/S-x-x-x-x-V/I (without a Tyr) was identified for phosphorylation-independent binding. Disease-causing SAP mutants showed binding defects explained by the structures.\",\n      \"method\": \"NMR structure determination + synthetic peptide array screening + hydrogen exchange studies\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — multiple NMR structures with functional validation and disease mutation interpretation, replicating and extending earlier structural work\",\n      \"pmids\": [\"11823424\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"SAP/SH2D1A was shown to associate with NTB-A (a novel SLAM-family receptor on NK and T cells) via tyrosine-based motifs in NTB-A's cytoplasmic tail. In XLP-NK cells lacking SAP, NTB-A-mediated signals switched from activating to inhibitory, contributing to the inability of XLP NK cells to kill EBV-infected B cells.\",\n      \"method\": \"Molecular cloning, co-immunoprecipitation, functional NK cytotoxicity assays with XLP patient cells, mAb masking experiments\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP plus functional cytotoxicity assays in primary patient cells with multiple orthogonal approaches\",\n      \"pmids\": [\"11489943\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"SH2D1A (SAP) regulates the association of CD150/SLAM with either SHIP or SHP-2: in SH2D1A-positive B cells, CD150 coprecipitates with SH2D1A and SHIP, whereas in SH2D1A-negative cells (including XLP patients), CD150 associates only with SHP-2. SAP facilitates SHIP binding to CD150 via TxYxxV/I immunoreceptor tyrosine-based switch motifs (ITSM) at Y281 and Y327.\",\n      \"method\": \"Co-immunoprecipitation with GST-fusion proteins containing point-mutant CD150 cytoplasmic tail (Y269F, Y281F, Y307F, Y327F) + comparison of XLP vs. normal B cell lines\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP with site-directed mutagenesis plus XLP patient cell comparison, multiple orthogonal methods\",\n      \"pmids\": [\"11313386\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"SAP serves dual functional roles in SLAM family signaling: (1) it acts as an adaptor to recruit FynT kinase to SLAM via direct interaction between the FynT SH3 domain and SAP, promoting SLAM tyrosine phosphorylation; (2) it competitively blocks SHP-2 and SHIP binding to SLAM family receptors. Disease-causing SAP mutants showed reduced affinities for both FynT and SLAM.\",\n      \"method\": \"In vitro and in vivo binding assays, peptide arrays from SLAM family receptors, co-immunoprecipitation in cells, kinase activity assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (peptide arrays, Co-IP, in vitro binding, functional kinase assays) with disease mutant validation\",\n      \"pmids\": [\"12458214\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Characterization of XLP-associated SH2D1A missense mutations identified two classes: (i) mutations causing decreased protein half-life (Y7C, S28R, Q99P, P101L, V102G, X129R) and (ii) mutations causing structural changes affecting receptor binding. Mutation T68I disrupted interaction with the hydrophobic cleft/Val+3 of the binding motif, abrogating binding to all four receptors (CD150, CD84, CD229, CD244). Mutation T53I selectively impaired phosphorylation-independent but not phosphotyrosine-dependent binding, and selectively abolished CD229/CD244 binding.\",\n      \"method\": \"In vitro binding assays, protein stability (half-life) measurements, site-directed mutagenesis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — detailed mutagenesis with functional binding assays across multiple XLP patient mutations\",\n      \"pmids\": [\"11477068\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"SH2D1A associates with Dok1 (p62dok) via its SH2 domain in a manner dependent on phosphorylation of Dok1 Y449. This interaction requires an intact SH2 domain (an XLP-associated SH2 domain mutant failed to bind). Overexpression of SH2D1A activates NF-κB in 293T cells through a pathway requiring IκB kinase β but independent of the wild-type SH2 domain.\",\n      \"method\": \"Co-immunoprecipitation, mass spectrometry identification of Dok1, overexpression in 293T cells, dominant-negative IKKβ inhibition\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP with identified binding site plus functional NF-κB activation assay, single lab\",\n      \"pmids\": [\"10852966\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"SAP (SH2D1A) regulates PI3K-dependent signaling downstream of the NK cell receptor 2B4: PI3K inhibitors (wortmannin or LY294002) prevent recruitment of SAP to 2B4 after 2B4 ligation without disrupting p85-2B4 association, and PI3K inhibition diminishes NK cytotoxicity in a manner dependent on SAP.\",\n      \"method\": \"Co-immunoprecipitation in primary NK cells, pharmacological PI3K inhibition, NK cytotoxicity assays with XLP patient cells\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP plus functional assays with patient comparison, single lab\",\n      \"pmids\": [\"11815622\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"SH2D1A expression in B cells is regulated by the adaptor's role in CD150/SLAM signaling: in DT40 B cells, CD150-mediated Akt phosphorylation requires Syk and SH2D1A (and is SHIP-independent), while CD150-mediated ERK pathway activation requires SHIP but not SH2D1A. Lyn directly phosphorylates Y327 of CD150.\",\n      \"method\": \"DT40 B cell sublines deficient in specific signaling molecules, phosphorylation assays, genetic epistasis\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis with defined cellular readout using clean KO sublines\",\n      \"pmids\": [\"15315965\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"SH2D1A gene transcription is driven by a basal promoter element containing an Ets consensus site bound by Ets-1 and Ets-2 transcription factors (confirmed by gel mobility supershift and dominant-negative overexpression). SH2D1A mRNA stability is regulated post-transcriptionally by competitive binding of AUF1 (destabilizing) and HuR (stabilizing) to the 3' UTR; the mRNA decays rapidly in mouse T cells.\",\n      \"method\": \"Promoter deletion analysis, gel mobility supershift assays, reporter gene assays, dominant-negative overexpression, RNA-gel mobility shift assays\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (promoter analysis, gel shift, dominant-negative) for transcriptional and post-transcriptional regulation\",\n      \"pmids\": [\"15459902\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"SAP encoded by SH2D1A is essential for NKT cell ontogeny in both mice and humans: Sh2d1a-/- mice completely lack NKT cells in thymus and peripheral organs, the defect is hematopoietic cell-autonomous (rescued by SAP-expressing bone marrow reconstitution), and 17 XLP patients with SH2D1A mutations also lacked NKT cells. Female XLP carriers show completely skewed X-chromosome inactivation within NKT cells but not T or B cells.\",\n      \"method\": \"Sh2d1a knockout mice, alphaGC stimulation, bone marrow reconstitution, analysis of XLP patient lymphocytes, X-inactivation analysis in female carriers\",\n      \"journal\": \"Nature medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — hematopoietic reconstitution experiment plus human patient validation plus X-inactivation analysis, multiple orthogonal methods\",\n      \"pmids\": [\"15711562\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"SAP-deficient mice recapitulate features of XLP, including increased IFN-γ production and decreased IL-4 production by anti-CD3-stimulated splenocytes, as well as reduced Ig-secreting cells after infection. This Th1 skewing indicates SAP controls cytokine balance in T cells.\",\n      \"method\": \"Targeted gene knockout in mice, infection with LCMV and Toxoplasma gondii, cytokine measurement, serum Ig analysis\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with defined cellular phenotype replicated across multiple infection models\",\n      \"pmids\": [\"11404475\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"SH2D1A is required for T-dependent humoral immune responses: SH2D1A-deficient mice showed severely impaired germinal center formation and T-dependent antigen-specific IgG production, while T-independent responses were intact. This positions SH2D1A as a specific regulator of T-dependent humoral immunity.\",\n      \"method\": \"Sh2d1a knockout mice, immunization with T-dependent and T-independent antigens, germinal center analysis, adoptive cotransfer experiments\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with specific phenotypic readout and adoptive transfer experiments establishing cell-autonomous requirement\",\n      \"pmids\": [\"15263031\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"SH2D1A is required in B cells for antigen-specific IgG production: adoptive cotransfer of hapten-primed SH2D1A-/- B cells with wild-type CD4+ T cells into irradiated recipients revealed intrinsic B cell defects. Germinal centers were absent in SH2D1A-/- mice, and SH2D1A protein was detectable in wild-type germinal center B cells.\",\n      \"method\": \"Sh2d1a knockout mice, adoptive cotransfer into irradiated/Rag2-/- recipients, germinal center analysis, immunohistochemistry\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — adoptive cotransfer with genetic dissection establishing B cell-intrinsic role, multiple approaches\",\n      \"pmids\": [\"15774582\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"SAP interacts with the SH3 domain of NCK1 (a novel partner) using the same surface on the SAP SH2 domain as the Fyn SH3 domain. SAP depletion by siRNA decreased NCK1 tyrosine phosphorylation and phosphorylation of TCR downstream proteins LAT and SLP-76. SAP regulated T cell proliferation through the MAP-kinase ERK pathway.\",\n      \"method\": \"NMR analysis of SAP-NCK1 SH3 interaction, SH3 domain panel screen, siRNA knockdown, phosphorylation assays, T cell proliferation assays\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — NMR binding characterization plus siRNA functional validation, single lab\",\n      \"pmids\": [\"18951976\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"SAP is required specifically for CD8+ T cell responses to antigen presented by B cells: in female XLP carriers with mixed SAP+/SAP- cells, EBV-specific memory CD8+ T cells were exclusively SAP+, whereas CMV- and influenza-specific cells were distributed across both populations. Blocking SLAM receptors NTB-A and 2B4 overcame the inability of SAP- CD8+ T cells to respond to B-cell antigen presentation, and ectopic NTB-A expression on fibroblasts inhibited SAP- CD8+ T cytotoxicity.\",\n      \"method\": \"Human XLP carrier model (natural mixed chimera), tetramer staining, SLAM receptor blocking antibodies, ectopic NTB-A expression on fibroblasts, cytotoxicity assays\",\n      \"journal\": \"PLoS biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — innovative human carrier model with multiple orthogonal mechanistic experiments establishing APC-type specificity of SAP requirement\",\n      \"pmids\": [\"22069374\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"SAP-deficient T cells exhibit impaired TCR restimulation-induced cell death (RICD) due to diminished TCR-induced inhibition of diacylglycerol kinase α (DGKα), leading to increased diacylglycerol metabolism and decreased Ras/PKCθ signaling. Pharmacological inhibition of DGKα restored diacylglycerol signaling at the immune synapse, rescued RICD via induction of NUR77 and NOR1 proapoptotic proteins, and prevented excessive CD8+ T cell expansion in SAP-deficient mice.\",\n      \"method\": \"SAP-deficient mouse model, LCMV infection, DGKα pharmacological inhibition, immune synapse imaging, apoptosis assays, cytokine measurements\",\n      \"journal\": \"Science translational medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — mechanistic pathway dissection with pharmacological rescue in both cellular and in vivo models, multiple readouts\",\n      \"pmids\": [\"26764158\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Differential DNA methylation of CpG-rich regions in the SH2D1A promoter and exon 1 correlates with tissue-specific gene expression: regions are hypomethylated in SAP-expressing T and NK cells but hypermethylated in non-expressing B cells and granulocytes.\",\n      \"method\": \"Bisulfite sequencing, methylation-sensitive restriction enzyme digestion in sorted cell populations\",\n      \"journal\": \"Immunogenetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct epigenetic measurement across multiple cell types with clear correlation, single lab\",\n      \"pmids\": [\"12709835\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Missense mutations in SH2D1A (Y54C, I84T, F87S) and an insertion mutation (fs82→X103) all dramatically reduced the protein half-life of SAP. The I84T mutation had no effect on binding to SLAM, CD84, or 2B4 yet still impaired SLAM-mediated downstream signaling, indicating that SAP binding and signaling functions can be dissociated.\",\n      \"method\": \"Primary lymphocyte and transfected cell line protein stability assays, receptor binding assays, downstream signaling readouts\",\n      \"journal\": \"International immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — functional dissection of binding vs. signaling using patient mutations in primary cells and cell lines\",\n      \"pmids\": [\"16720617\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Characterization of a G16D missense mutation in SAP: the mutant protein had comparable half-life to wild-type SAP but was defective in binding to its physiological ligands SLAM and 2B4, indicating loss-of-function through impaired receptor interaction rather than protein instability.\",\n      \"method\": \"Site-directed mutagenesis, COS cell expression, protein stability assays, receptor binding assays\",\n      \"journal\": \"Human mutation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vitro mutagenesis with functional binding assays dissecting mechanism of pathogenicity\",\n      \"pmids\": [\"15841490\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"SAP (encoded by SH2D1A) is an intracellular adaptor protein consisting almost entirely of a single SH2 domain that binds SLAM-family receptors (SLAM/CD150, 2B4/CD244, NTB-A, CD84, Ly9/CD229) via a unique 'three-pronged' mechanism recognizing residues both N-terminal and C-terminal to a tyrosine (in a phosphorylation-independent manner) and recruits the Src-family kinase FynT to these receptors through a direct SH3-domain interaction, while simultaneously competing with SHP-2 and SHIP for receptor binding; this dual adaptor/competitive-inhibitor function controls T cell and NK cell activation, germinal center formation and T-dependent humoral immunity, NKT cell development, CD8+ T cell responses to B-cell antigen presentation, and restimulation-induced cell death through regulation of diacylglycerol kinase α activity, with SAP expression itself controlled at the transcriptional level by Ets-1/Ets-2 and post-transcriptionally by AUF1/HuR-mediated mRNA stability, and epigenetically by differential CpG methylation determining cell-type-specific expression.\"\n}\n```\n\n--- ROUND 2 (R2/R3, augmented corpus) ---\n\n```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1998,\n      \"finding\": \"SH2D1A (SAP) was identified as the gene mutated in X-linked lymphoproliferative syndrome (XLP); it encodes a 128-amino-acid protein composed almost entirely of a single SH2 domain, expressed in T and NK cells, that acts as an inhibitor by blocking recruitment of the SH2-domain-containing signal-transduction molecule SHP-2 to a docking site in the SLAM (CD150) cytoplasmic region.\",\n      \"method\": \"Positional cloning, mutation analysis in XLP patients, co-immunoprecipitation, functional blocking assay\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — original discovery paper with multiple methods, independently confirmed by concurrent papers (Coffey et al., Nichols et al.)\",\n      \"pmids\": [\"9774102\", \"9771704\", \"9811875\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Crystal structures of SAP revealed it binds both phosphorylated and non-phosphorylated SLAM peptides using a mode that involves specific interactions with residues N-terminal to the tyrosine in addition to C-terminal contacts ('extended, phosphotyrosine-independent sequence recognition'), recognizing the motif TIpYXX(V/I). XLP-causing mutations were shown to disrupt these interactions.\",\n      \"method\": \"X-ray crystallography, phosphopeptide library screen, mutagenesis\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structures with mutagenesis and peptide library validation\",\n      \"pmids\": [\"10549287\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"The SAP SH2 domain binds SLAM peptides in a phosphorylation-independent manner with Kd ~330 nM (non-phospho) and ~150 nM (phospho), and NMR studies demonstrated a 'three-pronged' binding mechanism engaging both N-terminal and C-terminal residues flanking the tyrosine, distinct from canonical SH2 'two-pronged' binding.\",\n      \"method\": \"NMR spectroscopy (15N/13C-labeled SAP), fluorescence binding assays\",\n      \"journal\": \"Current biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — multi-field NMR with quantitative binding data, independently consistent with crystal structures\",\n      \"pmids\": [\"10607564\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"SAP regulates SLAM-mediated signaling in T cells by facilitating selective recruitment and activation of the Src-family kinase FynT to SLAM; in the absence of SAP, SLAM fails to trigger protein tyrosine phosphorylation and downstream signals involving SHIP, Dok2, Dok1, Shc, and RasGAP. SAP is thus an adaptor for FynT rather than merely an inhibitor of SHP-2.\",\n      \"method\": \"Reconstitution in T cell lines, co-immunoprecipitation, dominant-negative/knockout approaches, signaling assays in SAP-deficient cells\",\n      \"journal\": \"Nature immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods, reciprocal co-IP, loss-of-function with defined signaling phenotype\",\n      \"pmids\": [\"11477403\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"SAP associates with the novel SLAM-family receptor NTB-A (a 60-kD glycoprotein on NK, T, and B cells). In XLP-NK cells lacking SAP, NTB-A delivers inhibitory rather than activating signals, contributing to the inability of XLP-NK cells to kill EBV-infected B cells. SAP prevents NTB-A from recruiting inhibitory SHPs.\",\n      \"method\": \"Molecular cloning, co-immunoprecipitation, NK cell cytotoxicity assays with XLP patient cells, antibody-blocking experiments\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal co-IP, patient-derived cells, functional cytotoxicity readout\",\n      \"pmids\": [\"11489943\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"In B cells, SAP (SH2D1A) determines which phosphatase associates with CD150 (SLAM): when SAP is present, SHIP is recruited to phosphorylated Y281 and Y327 of CD150; when SAP is absent (as in XLP B cell lines), SHP-2 associates instead. SAP thus functions as a molecular switch (via the TxYxxV/I 'immunoreceptor tyrosine-based switch motif') regulating alternative downstream signaling.\",\n      \"method\": \"Co-immunoprecipitation, GST-fusion pulldowns with Y→F mutants of CD150, comparison of SAP-positive vs. SAP-negative B cell lines\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple cell lines, site-directed mutagenesis of binding motifs, comparison with XLP patient lines\",\n      \"pmids\": [\"11313386\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"SAP (SH2D1A) binds the SH3 domain of FynT directly, an interaction mediated through the surface of the SAP SH2 domain. In cells, FynT is indispensable for SLAM tyrosine phosphorylation and SAP dramatically enhances this phosphorylation while blocking SHP-2 recruitment. Disease-causing SAP mutants show significantly reduced affinity for both FynT and SLAM, confirming the dual adaptor/inhibitor role.\",\n      \"method\": \"In vitro peptide array binding, in vivo co-immunoprecipitation, kinase assays, site-directed mutagenesis of disease mutants\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — in vitro and in vivo binding assays plus disease mutant analysis with orthogonal methods\",\n      \"pmids\": [\"12458214\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"NMR structures of the SAP SH2 domain in complex with SLAM-derived peptides (with and without phosphotyrosine) provided direct structural evidence for the 'three-pronged' binding mechanism. The consensus binding sequence T/S-x-x-x-x-V/I (lacking Tyr or pTyr) is recognized via a surface distinct from canonical SH2 engagement. Structural mapping explained binding defects in XLP-causing SAP mutants.\",\n      \"method\": \"NMR structure determination, hydrogen exchange, synthetic peptide repertoire screening, disease mutant structural analysis\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — high-resolution NMR structures with functional validation and disease mutant analysis\",\n      \"pmids\": [\"11823424\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Analysis of XLP missense mutations identified two classes: (i) mutations reducing SAP protein half-life (Y7C, S28R, Q99P, P101L, V102G, X129R) and (ii) mutations that structurally impair binding to SLAM-family receptors (CD150, CD84, CD229, CD244). Mutant T53I selectively abolishes phosphorylation-independent interactions while preserving phosphotyrosine-dependent binding, and abrogates binding to CD229/CD224, demonstrating that SAP controls multiple distinct signaling pathways.\",\n      \"method\": \"Site-directed mutagenesis, protein half-life assays, GST-pulldown and co-immunoprecipitation with four SLAM-family receptors\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — systematic mutagenesis of 10 disease-causing alleles with multiple receptor binding assays\",\n      \"pmids\": [\"11477068\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Crystal structure of a ternary SLAM-SAP-Fyn-SH3 complex showed that the SAP SH2 domain binds the FynT SH3 domain through a non-canonical surface-surface interaction (not involving canonical SH3 or SH2 binding motifs), directly coupling FynT to SLAM. This binding mode is predicted to preclude Fyn's autoinhibited conformation, thereby promoting kinase activation upon recruitment.\",\n      \"method\": \"X-ray crystallography of ternary complex, biochemical binding assays\",\n      \"journal\": \"Nature cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — ternary complex crystal structure with mechanistic interpretation confirmed by biochemical data\",\n      \"pmids\": [\"12545174\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"SAP was shown to associate with 2B4 (CD244) on activated human NK cells and T cells, and this interaction prevented 2B4 from recruiting SHP-2. Loss of SAP in XLP leads to aberrant inhibitory signaling through 2B4, extending the pathological mechanism beyond SLAM to include other SLAM-family receptors.\",\n      \"method\": \"Co-immunoprecipitation in activated cells, functional assays with pervanadate-stimulated transfectants\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal co-IP in primary cells and transfected cells, mechanistic follow-up with competition experiments\",\n      \"pmids\": [\"10358138\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Cell surface receptors Ly-9 (CD229) and CD84 also recruit SAP through their cytoplasmic TxYxxV/I motifs, particularly when their tyrosine residues are phosphorylated, as shown by yeast two-hybrid, COS cell transfection, and lymphoid cell assays. SAP regulation of SLAM-family signaling therefore extends to at least four receptors (SLAM, 2B4, CD84, Ly-9).\",\n      \"method\": \"Yeast two-hybrid, COS cell co-transfection/co-immunoprecipitation, lymphoid cell co-immunoprecipitation\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple independent experimental systems confirming SAP interaction with two new receptors\",\n      \"pmids\": [\"11389028\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"SH2D1A (SAP) associates with Dok1 (p62dok) in a manner dependent on phosphorylation of Dok1 Y449; an XLP-associated SH2 domain mutant fails to associate with Dok1. Overexpression of SH2D1A activates NF-κB in 293T cells through a mechanism requiring IκB kinase β but independent of the SH2 domain.\",\n      \"method\": \"Co-immunoprecipitation, lane-shift SH2 domain mutant analysis, NF-κB reporter assays, dominant-negative IKKβ\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — single-lab study with co-IP and reporter assays; NF-κB activation mechanism not further validated\",\n      \"pmids\": [\"10852966\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"SAP (SH2D1A) association with 2B4 in NK cells is dependent on PI3K activity: PI3K inhibitors (wortmannin, LY294002) prevent SAP recruitment to 2B4 after 2B4 ligation without altering the 2B4–p85 association, and PI3K inhibition significantly reduces NK cell cytotoxicity in a SAP-dependent manner.\",\n      \"method\": \"Co-immunoprecipitation with pharmacological PI3K inhibitors in primary NK cells, NK cell cytotoxicity assays, XLP patient NK cells as controls\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — single-lab study using pharmacological inhibitors with functional readout; PI3K-SAP mechanistic link not further molecularly dissected\",\n      \"pmids\": [\"11815622\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"CD150 (SLAM)-mediated Akt phosphorylation in B cells requires Syk and SH2D1A (SAP), is negatively regulated by Lyn and Btk, and is SHIP-independent. CD150-mediated ERK activation requires SHIP but not SAP. SAP thus acts as a switch between CD150-initiated signaling pathways, directing signaling towards Akt rather than ERK.\",\n      \"method\": \"DT40 B cell sublines deficient in specific signaling molecules, stimulation assays, phospho-specific western blotting\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis in isogenic DT40 knockout cell lines with two defined pathway readouts\",\n      \"pmids\": [\"15315965\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"SH2D1A-deficient mice cannot form germinal centers upon immunization, and both SAP-deficient T cells and B cells have functional defects impairing T-dependent IgG antibody responses. Adoptive co-transfer experiments demonstrated that SAP expression is required in B cells for antigen-specific IgG production, identifying a B cell-intrinsic role for SAP.\",\n      \"method\": \"Knockout mouse model, adoptive co-transfer experiments (KO B cells + WT T cells, and vice versa), germinal center histology\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis with adoptive transfer and germinal center analysis, defining cell-autonomous B cell role\",\n      \"pmids\": [\"15774582\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"SH2D1A deficiency protects mice from T-dependent humoral autoimmunity (experimental lupus) by blocking germinal center formation and T-dependent antibody responses, while leaving T-independent responses intact. This identifies the SLAM-SH2D1A axis as specifically required for T-dependent humoral immunity.\",\n      \"method\": \"Sh2d1a−/− mouse lupus model, germinal center analysis, T-dependent vs. T-independent immunization, EAE susceptibility\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple disease models in KO mice with mechanistic dissection of T-dependent vs. T-independent pathways\",\n      \"pmids\": [\"15263031\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"SAP and the SLAM-family receptor NTB-A cooperate to regulate TCR-induced restimulation-induced cell death (RICD) in activated T cells. SAP/NTB-A signaling augments proximal TCR signaling strength to reach the threshold for apoptosis; upon TCR restimulation, SAP is increasingly recruited to NTB-A while SHP-1 dissociates. SAP-deficient T cells (XLP) resist RICD, and blocking NTB-A in normal T cells recapitulates XLP-like RICD resistance.\",\n      \"method\": \"XLP patient T cells, siRNA knockdown, antibody blockade, co-immunoprecipitation time-course, apoptosis assays\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — patient-derived cells plus knockdown/blockade with mechanistic molecular readouts and apoptosis phenotype\",\n      \"pmids\": [\"19759517\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"SAP is essential for NKT cell development in both mice and humans; Sh2d1a−/− mice and XLP patients (confirmed by germline SH2D1A mutations) completely lack NKT cells in thymus and periphery. The defect is hematopoietic cell-autonomous and rescued by reconstitution of SAP expression in bone marrow. Female XLP carriers show completely skewed X-chromosome inactivation within NKT cells but not T or B cells.\",\n      \"method\": \"Knock-out mouse analysis, analysis of XLP patient lymphocyte subsets, bone marrow reconstitution, X-inactivation skewing analysis in XLP carriers\",\n      \"journal\": \"Nature medicine / The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — two independent labs (Nichols et al. and Pasquier et al.) confirmed SAP-dependent NKT development with cell-autonomous rescue\",\n      \"pmids\": [\"15711562\", \"15738056\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"SAP-deficient CTLs from XLP patients show specific lytic defects against EBV-positive B cells, associated with impaired polarization of 2B4, perforin, and lipid rafts to the contact zone. Blockade of 2B4 in normal CTLs reproduces the SAP-deficient polarization defect, demonstrating that the SAP/2B4 pathway directs lytic machinery polarization toward EBV-positive targets.\",\n      \"method\": \"XLP patient CTL cytotoxicity assays, immunofluorescence microscopy of immunological synapse, 2B4 antibody blockade\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — patient cells plus antibody blockade mimicking KO phenotype with defined polarization readout\",\n      \"pmids\": [\"15677558\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"2B4 signals activate NK cells through a mechanism strictly dependent on SAP: SAP binds all 4 ITSMs of 2B4 in a phosphorylation-dependent manner and acts as an inhibitor of negative regulators (SHP-1, SHP-2, SHIP, Csk) at the third ITSM. Fyn can also associate with phosphorylated 2B4, and both Fyn and Csk can phosphorylate 2B4.\",\n      \"method\": \"Structure-function mutagenesis of 2B4 ITSMs, co-immunoprecipitation, kinase phosphorylation assays in NK cell lines\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — systematic ITSM mutagenesis with kinase assays and competitive binding experiments\",\n      \"pmids\": [\"15713798\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"2B4-induced tyrosine phosphorylation signaling in NK cells (involving 2B4, Vav-1, and SHIP-1) is absolutely dependent on co-expression of SAP and requires Arg78 of SAP (the FynT-binding residue). This confirmed that SAP promotes 2B4 signaling by recruiting FynT, and established that SLAM and 2B4 trigger distinct tyrosine phosphorylation profiles despite both requiring SAP.\",\n      \"method\": \"NK cell line reconstitution, structure-function mutagenesis (R78 of SAP), co-immunoprecipitation, tyrosine phosphorylation assays\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — SAP point mutant specifically disrupting FynT binding eliminates 2B4 signaling; genetic epistasis in reconstituted cells\",\n      \"pmids\": [\"15169881\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"SAP interacts with the SH3 domains of NCK1 (a novel binding partner) as well as FynT via the same surface on the SAP SH2 domain. NMR analysis showed NCK1-SH3 and Fyn-SH3 engage the same residues on SAP with comparable affinities. SAP depletion by siRNA reduces NCK1 tyrosine phosphorylation and downstream TCR signaling (LAT, SLP-76 phosphorylation) and impairs T cell proliferation via the MAP kinase Erk pathway.\",\n      \"method\": \"SH3 domain panel screen, NMR binding analysis, siRNA knockdown, phospho-western blotting, T cell proliferation assays\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — NMR binding plus siRNA phenotype with defined signaling readouts, single-lab study\",\n      \"pmids\": [\"18951976\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"SH2D1A gene expression is controlled by a combination of transcriptional and post-transcriptional mechanisms: the basal promoter contains an Ets consensus site bound by Ets-1 and Ets-2 (shown by gel mobility shift/supershift and dominant-negative overexpression). SH2D1A mRNA is rapidly degraded in T cells via its 3' UTR through a balance between destabilizing factor AUF1 and stabilizing factor HuR, though the degradation rate itself is not altered by TCR engagement.\",\n      \"method\": \"Promoter deletion analysis, gel mobility shift and supershift assays, dominant-negative transcription factor overexpression, RNA decay assays, RNA-gel mobility shift assays\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple molecular assays identifying transcriptional and post-transcriptional regulators, single-lab study\",\n      \"pmids\": [\"15459902\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"XLP missense mutations (Y54C, I84T, F87S) and an insertion (fs82→X103) each dramatically reduce SAP protein half-life. Y54C and F87S additionally impair receptor binding, while I84T does not affect binding to SLAM, CD84, or 2B4 but nonetheless reduces downstream SLAM signaling, demonstrating that reduced SAP stability is sufficient to impair signaling even when binding affinity is preserved.\",\n      \"method\": \"Patient-derived lymphocytes and transfected cell lines, protein stability assays, receptor co-immunoprecipitation, downstream signaling assays\",\n      \"journal\": \"International immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — four distinct disease alleles characterized with protein stability and functional assays, single lab\",\n      \"pmids\": [\"16720617\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"In female XLP carriers (natural mixed SAP+/SAP- chimeras due to random X-inactivation), EBV-specific CD8+ T cells were exclusively SAP+, while CMV- and influenza-specific memory cells were distributed across both populations. Blocking SLAM receptors NTB-A and 2B4 (not EBV itself) restored cytotoxicity of SAP- CD8+ T cells against EBV-infected B cells; ectopic NTB-A expression on fibroblasts inhibited SAP- CTL cytotoxicity. This demonstrated that SLAM receptors acquire inhibitory function in the absence of SAP and that susceptibility to EBV in XLP reflects the nature of the antigen-presenting cell (B cells express SLAM receptors), not a direct effect of EBV.\",\n      \"method\": \"Human XLP carrier lymphocyte analysis, SLAM receptor blockade experiments, ectopic NTB-A expression on fibroblasts, antigen-specific T cell functional assays\",\n      \"journal\": \"PLoS biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — natural human chimera model with mechanistic gain-of-function and blockade experiments, multiple orthogonal approaches\",\n      \"pmids\": [\"22069374\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"SAP-deficient T cells exhibit impaired TCR restimulation-induced cell death (RICD) due to diminished TCR-induced inhibition of diacylglycerol kinase α (DGKα), leading to increased DAG metabolism and decreased Ras/PKCθ signaling. Pharmacological or genetic inhibition of DGKα in SAP-deficient T cells restores DAG signaling at the immune synapse and rescues RICD via NUR77 and NOR1 pro-apoptotic proteins. DGKα inhibition also prevents excessive CD8+ T cell expansion and IFN-γ in SAP-deficient mice after LCMV infection without impairing lytic activity.\",\n      \"method\": \"SAP-deficient T cells from XLP patients, DGKα inhibitors, in vivo LCMV mouse model, immune synapse imaging, apoptosis/signaling assays\",\n      \"journal\": \"Science translational medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — mechanistic pathway dissection with pharmacological rescue in patient cells and in vivo mouse model\",\n      \"pmids\": [\"26764158\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Differential methylation of CpG-rich regions in the 5' region and exon 1 of the SH2D1A gene correlates with cell lineage-specific transcription: the gene is hypomethylated in T/NK cells (which express it) and hypermethylated in B cells and granulocytes (which do not).\",\n      \"method\": \"Bisulfite sequencing, methylation-sensitive restriction enzyme digestion\",\n      \"journal\": \"Immunogenetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — correlation of methylation with expression across cell types, no causal intervention experiment\",\n      \"pmids\": [\"12709835\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"SH2D1A encodes SAP, a lymphocyte-specific adaptor protein composed of a single SH2 domain that binds SLAM-family receptors (SLAM/CD150, 2B4/CD244, NTB-A, CD84, Ly-9) via a unique 'three-pronged,' partially phosphorylation-independent mechanism; SAP serves dual functions—blocking recruitment of inhibitory SHP-2/SHP-1 phosphatases to these receptors, and recruiting/activating the Src-family kinase FynT via a non-canonical SH2-SH3 surface interaction—thereby promoting positive signaling cascades required for NKT cell development, germinal center formation, T-dependent humoral immunity, NK/CTL cytotoxicity, and TCR restimulation-induced apoptosis, with loss of SAP causing inappropriate inhibitory SLAM-family receptor signaling and the immunopathology of X-linked lymphoproliferative disease.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"SH2D1A encodes SAP, a small SH2-domain adaptor protein that controls T cell, NK cell, NKT cell, and B cell function by coupling SLAM-family receptors to downstream signaling while blocking recruitment of inhibitory phosphatases. SAP binds SLAM-family receptors (SLAM/CD150, 2B4, NTB-A, CD84, Ly9) through a distinctive three-pronged SH2 domain interaction that engages residues both N-terminal and C-terminal to the tyrosine motif in a phosphorylation-independent manner, and recruits FynT kinase via a direct SH3-domain interaction while competitively displacing SHP-2 and SHIP [PMID:10549287, PMID:12458214]. SAP is essential for germinal center formation and T-dependent humoral immunity, NKT cell development, CD8+ T cell responses to B-cell antigen presentation, and restimulation-induced cell death through regulation of diacylglycerol kinase α activity [PMID:15263031, PMID:15711562, PMID:22069374, PMID:26764158]. Loss-of-function mutations in SH2D1A cause X-linked lymphoproliferative disease (XLP), with pathogenic mutations acting through either reduced protein stability or impaired receptor binding [PMID:11477068, PMID:16720617].\",\n  \"teleology\": [\n    {\n      \"year\": 1999,\n      \"claim\": \"Structural determination of the SAP SH2 domain revealed how it binds SLAM peptides in a phosphorylation-independent manner through contacts both N- and C-terminal to the tyrosine, establishing a binding mode distinct from conventional SH2 domains and explaining how XLP-associated mutations disrupt function.\",\n      \"evidence\": \"Crystal structures (X-ray) and NMR spectroscopy with phosphorylated and nonphosphorylated SLAM peptides, validated by peptide library screening and XLP mutation analysis\",\n      \"pmids\": [\"10549287\", \"10607564\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis for selectivity among different SLAM-family receptor peptides not fully resolved\", \"No structural data on SAP in complex with full-length receptors or downstream effectors\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Functional studies established that SAP acts as a molecular switch at SLAM-family receptors: it determines whether SLAM associates with SHIP versus SHP-2, and its absence in XLP patient NK cells converts the NTB-A receptor from activating to inhibitory, directly linking SAP loss to defective EBV-infected B cell killing.\",\n      \"evidence\": \"Co-immunoprecipitation with point-mutant CD150 tails in XLP vs. normal B cells; NK cytotoxicity assays with XLP patient cells and mAb masking\",\n      \"pmids\": [\"11313386\", \"11489943\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which SAP presence favors SHIP over SHP-2 recruitment not resolved at structural level\", \"Whether signaling switch applies uniformly to all SLAM-family receptors in all cell types\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Systematic analysis of XLP-associated missense mutations revealed two distinct pathogenic mechanisms — reduced protein half-life versus impaired receptor binding — and showed that individual mutations can selectively disrupt phosphorylation-independent but not phosphotyrosine-dependent binding, explaining receptor-specific phenotypes.\",\n      \"evidence\": \"In vitro binding assays across four SLAM-family receptors with site-directed mutagenesis and protein stability measurements\",\n      \"pmids\": [\"11477068\", \"16720617\", \"15841490\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether protein instability mutants retain partial function in vivo\", \"Genotype-phenotype correlations across full spectrum of XLP clinical manifestations\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Identification of FynT as a direct SAP effector established the dual adaptor/competitive-inhibitor model: SAP simultaneously recruits FynT kinase via SH3 domain interaction and blocks SHP-2/SHIP binding, resolving how a single SH2-only adaptor can positively transduce signals from SLAM-family receptors.\",\n      \"evidence\": \"Peptide arrays, co-immunoprecipitation, in vitro kinase assays, and NMR structural refinement of three-pronged binding\",\n      \"pmids\": [\"12458214\", \"11823424\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relative contributions of FynT recruitment versus phosphatase exclusion to downstream signaling outcomes not quantified\", \"Whether other Src-family kinases are recruited in specific cellular contexts\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"In vivo studies using SAP-deficient mice demonstrated that SH2D1A is specifically required for T-dependent humoral immunity and germinal center formation while T-independent responses remain intact, positioning SAP as a critical regulator of T-B cooperation.\",\n      \"evidence\": \"Sh2d1a knockout mice immunized with T-dependent and T-independent antigens, adoptive cotransfer experiments\",\n      \"pmids\": [\"15263031\", \"11404475\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular mechanism by which SAP in T cells promotes germinal center B cell responses not identified\", \"Whether SAP controls T follicular helper cell differentiation specifically\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"SAP was shown to be essential for NKT cell development in both mice and humans and to have a B cell-intrinsic role in humoral immunity, broadening its function beyond T/NK cell signaling to multiple hematopoietic lineages.\",\n      \"evidence\": \"Sh2d1a knockout mice, bone marrow reconstitution, adoptive cotransfer of SAP-/- B cells, analysis of XLP patients, X-inactivation analysis in female carriers\",\n      \"pmids\": [\"15711562\", \"15774582\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stage of NKT cell ontogeny at which SAP is required not defined\", \"Which SLAM-family receptor interaction mediates the B cell-intrinsic function\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Identification of NCK1 as a novel SAP-interacting partner using the same SH2 domain surface as FynT connected SAP to proximal TCR signaling (LAT, SLP-76 phosphorylation) and ERK-dependent T cell proliferation.\",\n      \"evidence\": \"NMR analysis of SAP-NCK1 SH3 interaction, SH3 domain panel screen, siRNA knockdown with phosphorylation readouts\",\n      \"pmids\": [\"18951976\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Competitive or cooperative relationship between FynT and NCK1 binding to SAP not resolved\", \"Physiological relevance of NCK1 interaction not validated in primary T cells or in vivo\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Using female XLP carriers as natural chimeras, SAP was shown to be specifically required for CD8+ T cell responses to B cell-presented antigens (including EBV) but not to antigens from other APCs, and this selectivity was traced to inhibitory signaling through NTB-A and 2B4 on SAP-deficient cells encountering B cells.\",\n      \"evidence\": \"Tetramer staining of SAP+/SAP- CD8+ T cells in XLP carriers, SLAM receptor blocking antibodies, ectopic NTB-A expression on fibroblasts\",\n      \"pmids\": [\"22069374\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Why B cells uniquely trigger inhibitory SLAM-family signaling in the absence of SAP not mechanistically resolved\", \"Whether this APC-type selectivity fully explains EBV susceptibility in XLP\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"The mechanism linking SAP deficiency to lymphoproliferation was resolved: SAP-deficient T cells fail to inhibit diacylglycerol kinase α upon TCR restimulation, resulting in impaired RICD; pharmacological DGK inhibition restored diacylglycerol signaling and RICD, preventing excessive CD8+ T cell expansion in vivo.\",\n      \"evidence\": \"SAP-deficient mice infected with LCMV, DGKα pharmacological inhibition, immune synapse imaging, apoptosis assays\",\n      \"pmids\": [\"26764158\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether SAP directly interacts with DGKα or acts through an intermediary\", \"Long-term safety and efficacy of DGK inhibition as therapeutic strategy for XLP\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How SAP coordinates its multiple binding partners (FynT, NCK1, SLAM-family receptors) in space and time at the immune synapse, and the structural basis of SAP-mediated DGKα regulation, remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No structural model of ternary SAP-receptor-FynT complex\", \"Mechanism of DGKα regulation by SAP unknown\", \"How SAP expression levels are dynamically regulated during immune responses not characterized in vivo\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 1, 2, 5]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [4, 5, 17]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [5, 15]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [3, 11, 12, 13, 16, 17]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [5, 8, 9, 15]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [11]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"SLAM\", \"2B4\", \"NTB-A\", \"CD84\", \"FYN\", \"NCK1\", \"SHIP1\", \"SHP2\"],\n    \"other_free_text\": []\n  }\n}\n```\n\n--- ROUND 2 (R2/R3, augmented corpus) ---\n\n```json\n{\n  \"mechanistic_narrative\": \"SH2D1A encodes SAP, a small lymphocyte-specific adaptor protein composed almost entirely of a single SH2 domain that serves as a master regulator of SLAM-family receptor signaling in T, NK, and NKT cells. SAP binds the immunoreceptor tyrosine-based switch motifs (ITSMs) of SLAM-family receptors (SLAM/CD150, 2B4/CD244, NTB-A, CD84, Ly-9) via a unique three-pronged mechanism that recognizes both phosphorylated and non-phosphorylated TIpYXX(V/I) peptides, simultaneously blocking recruitment of the inhibitory phosphatases SHP-1/SHP-2 and recruiting the Src-family kinase FynT through a non-canonical SH2–SH3 surface interaction that promotes kinase activation [PMID:9774102, PMID:10549287, PMID:11477403, PMID:12545174]. This dual adaptor/inhibitor function is essential for NKT cell development, germinal center formation, T-dependent humoral immunity, NK/CTL cytotoxicity against EBV-infected B cells, and TCR restimulation-induced cell death (RICD), with RICD requiring SAP-dependent suppression of diacylglycerol kinase α to sustain DAG-Ras signaling [PMID:15711562, PMID:15774582, PMID:15677558, PMID:19759517, PMID:26764158]. Loss-of-function mutations in SH2D1A cause X-linked lymphoproliferative disease (XLP), in which SLAM-family receptors acquire inappropriate inhibitory signaling due to unopposed SHP recruitment, leading to fatal EBV-driven immunopathology, dysgammaglobulinemia, and lymphoma [PMID:9774102, PMID:22069374].\",\n  \"teleology\": [\n    {\n      \"year\": 1998,\n      \"claim\": \"Positional cloning of SH2D1A as the gene mutated in X-linked lymphoproliferative disease established that a single-SH2-domain adaptor protein controls SLAM signaling by competing with SHP-2 for binding to SLAM's cytoplasmic tail — defining the molecular basis of XLP.\",\n      \"evidence\": \"Positional cloning, mutation analysis in XLP families, co-immunoprecipitation and SHP-2 competition assays\",\n      \"pmids\": [\"9774102\", \"9771704\", \"9811875\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Mechanism by which SAP loss causes the diverse clinical manifestations of XLP was unknown\",\n        \"Whether SAP interacts with receptors beyond SLAM was not addressed\"\n      ]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Structural studies revealed that SAP employs a unique three-pronged binding mode recognizing residues N-terminal and C-terminal to the tyrosine — explaining how SAP engages both phosphorylated and non-phosphorylated SLAM peptides and why XLP mutations disrupt these contacts.\",\n      \"evidence\": \"X-ray crystallography and NMR of SAP–SLAM peptide complexes, phosphopeptide library screening, quantitative fluorescence binding\",\n      \"pmids\": [\"10549287\", \"10607564\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"How this binding mode translated into downstream signaling beyond SHP-2 blocking was unknown\",\n        \"Whether non-canonical binding extended to other SLAM-family receptors was untested\"\n      ]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Discovery that SAP associates with 2B4 (CD244) on NK cells and blocks SHP-2 recruitment extended the SAP-controlled signaling network beyond SLAM to other SLAM-family receptors, broadening the molecular explanation for NK cell dysfunction in XLP.\",\n      \"evidence\": \"Co-immunoprecipitation in activated primary NK cells and transfectants\",\n      \"pmids\": [\"10358138\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Full repertoire of SLAM-family receptors engaging SAP was not yet defined\",\n        \"The positive signaling arm downstream of SAP at 2B4 was uncharacterized\"\n      ]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Reconstitution experiments overturned the purely inhibitory model of SAP by showing it actively recruits and activates FynT to SLAM, enabling downstream phosphorylation cascades involving SHIP, Dok1/2, Shc, and RasGAP — redefining SAP as a dual adaptor/blocker.\",\n      \"evidence\": \"SAP-deficient T cell reconstitution, dominant-negative FynT, co-immunoprecipitation, kinase assays\",\n      \"pmids\": [\"11477403\", \"12458214\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Structural basis for the non-canonical SAP SH2–FynT SH3 interaction was not yet resolved\",\n        \"Whether FynT recruitment was required for all SLAM-family receptor signaling was unknown\"\n      ]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Identification of NTB-A, CD84, and Ly-9 as additional SAP-binding SLAM-family receptors, together with the ITSM molecular switch concept (SAP presence directing SHIP recruitment at SLAM instead of SHP-2), established SAP as a global regulator of an entire receptor family.\",\n      \"evidence\": \"Co-immunoprecipitation, yeast two-hybrid, GST-pulldown with Y→F mutants, XLP patient B cell lines\",\n      \"pmids\": [\"11489943\", \"11389028\", \"11313386\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Relative functional importance of individual SLAM-family receptors in XLP pathology was unclear\",\n        \"B cell-intrinsic SAP functions had not been tested in vivo\"\n      ]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Systematic characterization of XLP missense mutations identified two pathogenic mechanisms — reduced protein stability and impaired receptor binding — and showed that mutation T53I selectively ablates phosphorylation-independent binding, dissecting distinct SAP interaction modes.\",\n      \"evidence\": \"Ten disease alleles analyzed by site-directed mutagenesis, protein half-life assays, GST-pulldown with four SLAM-family receptors\",\n      \"pmids\": [\"11477068\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Genotype–phenotype correlations in XLP patients were not addressed\",\n        \"Whether stability-reducing mutations could be pharmacologically rescued was unknown\"\n      ]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"The ternary SLAM–SAP–FynT crystal structure revealed a non-canonical SH2–SH3 surface interaction that directly couples FynT to the receptor and is predicted to relieve Fyn autoinhibition, providing the structural mechanism for SAP-mediated kinase activation.\",\n      \"evidence\": \"X-ray crystallography of ternary complex, biochemical binding validation\",\n      \"pmids\": [\"12545174\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Direct demonstration that the ternary complex relieves Fyn autoinhibition in cells was lacking\",\n        \"Whether other SH3-domain proteins (e.g. NCK1) compete for the same SAP surface was untested\"\n      ]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"In vivo studies in SAP-deficient mice demonstrated that SAP is indispensable for germinal center formation and T-dependent humoral immunity, with adoptive transfer experiments revealing a B cell-intrinsic role for SAP, while protection from lupus models identified the SLAM–SAP axis as a specific checkpoint for autoimmune humoral responses.\",\n      \"evidence\": \"Sh2d1a−/− mice, adoptive co-transfer of SAP-KO vs. WT B and T cells, germinal center histology, lupus and EAE models\",\n      \"pmids\": [\"15774582\", \"15263031\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Molecular mechanism of SAP function within B cells during germinal center reactions was undefined\",\n        \"Whether SAP loss in T follicular helper cells was the dominant defect was debated\"\n      ]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"FynT Arg78-dependent reconstitution of 2B4 signaling in NK cells confirmed that SAP promotes activating 2B4 signals by recruiting FynT, and revealed SLAM and 2B4 trigger distinct downstream phosphorylation profiles despite sharing SAP/FynT dependency.\",\n      \"evidence\": \"NK cell line reconstitution with SAP R78A mutant, co-immunoprecipitation, phosphorylation assays\",\n      \"pmids\": [\"15169881\", \"15713798\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Receptor-specific downstream signaling pathways were incompletely mapped\",\n        \"How SLAM-family receptors cooperate or compete for limited SAP was unknown\"\n      ]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"SAP was shown to be absolutely required for NKT cell development in both mice and humans, with XLP carriers showing complete X-inactivation skewing in the NKT compartment — demonstrating a non-redundant developmental checkpoint controlled by SAP.\",\n      \"evidence\": \"Sh2d1a−/− mice, XLP patient lymphocyte subsets, bone marrow reconstitution, X-inactivation analysis in female carriers\",\n      \"pmids\": [\"15711562\", \"15738056\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Stage of NKT cell development blocked by SAP deficiency was not precisely defined\",\n        \"Which SLAM-family receptor(s) mediate SAP-dependent NKT selection was unknown\"\n      ]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"SAP-deficient CTLs from XLP patients showed defective polarization of perforin, 2B4, and lipid rafts toward EBV-infected B cells, with 2B4 blockade phenocopying this defect — establishing SAP/2B4 as directors of lytic synapse formation against EBV-positive targets.\",\n      \"evidence\": \"XLP patient CTL cytotoxicity, immunofluorescence of immunological synapse, 2B4 antibody blockade\",\n      \"pmids\": [\"15677558\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether NTB-A cooperates with 2B4 at the lytic synapse was not resolved\",\n        \"The signaling cascade linking SAP/2B4 to cytoskeletal polarization machinery was unknown\"\n      ]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Identification of NCK1 as a novel SAP SH2-domain partner competing with FynT for the same non-canonical surface expanded the adaptor network through which SAP modulates TCR-proximal signaling (LAT, SLP-76, ERK pathway).\",\n      \"evidence\": \"SH3 domain panel screen, NMR binding, siRNA knockdown with phospho-signaling readouts\",\n      \"pmids\": [\"18951976\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Relative in vivo contribution of NCK1 vs. FynT binding to SAP function was unclear\",\n        \"Whether NCK1–SAP interaction operates in NK cells or only in T cells was untested\"\n      ]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"SAP and NTB-A were shown to cooperate in promoting TCR restimulation-induced cell death (RICD), with SAP progressively displacing SHP-1 from NTB-A to amplify TCR signal strength above the apoptotic threshold — explaining why SAP-deficient T cells resist RICD and accumulate during viral infections.\",\n      \"evidence\": \"XLP patient T cells, siRNA knockdown, antibody blockade, co-immunoprecipitation time-course, apoptosis assays\",\n      \"pmids\": [\"19759517\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Downstream effector pathway linking amplified TCR signaling to the apoptotic program was not delineated\",\n        \"Whether other SLAM-family receptors contribute to RICD was untested\"\n      ]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Natural chimera analysis in female XLP carriers demonstrated that SLAM-family receptors (NTB-A, 2B4) on B cells actively inhibit SAP-negative CTLs — proving that EBV susceptibility in XLP reflects inhibitory SLAM signaling against B cell targets, not a virus-specific defect.\",\n      \"evidence\": \"X-inactivation mosaicism in XLP carriers, SLAM receptor blockade restoring SAP− CTL killing, ectopic NTB-A on fibroblasts\",\n      \"pmids\": [\"22069374\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether therapeutic SLAM receptor blockade could benefit XLP patients was not tested clinically\",\n        \"Contribution of each individual SLAM-family receptor to inhibitory signaling was not quantified\"\n      ]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Mechanistic dissection revealed that SAP promotes RICD by enabling TCR-induced inhibition of diacylglycerol kinase α (DGKα), sustaining DAG–Ras–PKCθ signaling; pharmacological DGKα inhibition rescued RICD in SAP-deficient cells and prevented lethal CD8+ T cell expansion in SAP-deficient mice after LCMV infection — identifying a druggable node downstream of SAP.\",\n      \"evidence\": \"XLP patient T cells, DGKα inhibitors/genetic approaches, LCMV infection in Sh2d1a−/− mice, immune synapse imaging\",\n      \"pmids\": [\"26764158\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"How SAP mechanistically suppresses DGKα enzymatic activity was not defined\",\n        \"Clinical translation of DGKα inhibition in XLP patients has not been tested\",\n        \"Whether DGKα inhibition also rescues germinal center or NKT cell defects in SAP deficiency is unknown\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The precise mechanism by which SAP controls NKT cell development, the SLAM-family receptor(s) mediating this checkpoint, the structural basis for SAP-dependent DGKα regulation, and whether therapeutic targeting of DGKα or SLAM receptors can benefit XLP patients remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Stage-specific SLAM-family receptor requirement for NKT cell selection is undefined\",\n        \"Molecular mechanism linking SAP to DGKα suppression is unknown\",\n        \"No clinical trial data exist for DGKα inhibition or SLAM receptor blockade in XLP\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 3, 6, 9, 21]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 5, 17, 20]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [0, 3]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [3, 17, 19]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [0, 3, 4, 10, 15, 16, 18, 25]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [3, 5, 9, 14, 21, 26]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [17, 26]}\n    ],\n    \"complexes\": [\n      \"SLAM-SAP-FynT ternary complex\"\n    ],\n    \"partners\": [\n      \"SLAMF1\",\n      \"CD244\",\n      \"SLAMF6\",\n      \"CD84\",\n      \"LY9\",\n      \"FYN\",\n      \"NCK1\",\n      \"PTPN6\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}