{"gene":"KLRD1","run_date":"2026-06-10T02:59:49","timeline":{"discoveries":[{"year":1996,"finding":"CD94 glycoproteins form disulfide-bonded heterodimers with NKG2A/B, NKG2C, and NKG2E glycoproteins. NKG2A/B possesses two ITIM sequences in its cytoplasmic domain responsible for inhibitory function, whereas other NKG2 proteins lack ITIMs and may transmit positive signals.","method":"Biochemical co-immunoprecipitation, SDS-PAGE, sequence analysis of cytoplasmic domains","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — reciprocal biochemical characterization replicated across multiple labs; foundational structural/biochemical finding confirmed by subsequent studies","pmids":["8943374"],"is_preprint":false},{"year":1996,"finding":"CD94 exists in at least two biochemically and serologically distinct forms: an inhibitory form (~43 kDa, group B clones) and a stimulatory form (~39 kDa, group A clones). The inhibitory form is selectively recognized by the Z199 mAb. CD94 is assembled as a disulfide-linked dimer.","method":"Immunoprecipitation, SDS-PAGE, N-glycanase and V8 protease digestion, reverse ADCC functional assays","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — multiple orthogonal biochemical methods in single study, confirmed by subsequent structural studies","pmids":["8955184"],"is_preprint":false},{"year":1997,"finding":"The inhibitory NK cell receptor is a covalent heterodimer of CD94 and NKG2-A (~43 kDa). NKG2-B, an alternatively spliced product of NKG2-A, also assembles with CD94. Both NKG2-A and NKG2-B contain cytoplasmic ITIMs providing the molecular basis for inhibitory function.","method":"Co-immunoprecipitation with anti-CD94 mAb, SDS-PAGE, identification of NKG2-A protein, ITIM sequence analysis","journal":"European journal of immunology","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — co-IP with biochemical characterization, independently confirmed by multiple labs","pmids":["9045931"],"is_preprint":false},{"year":1997,"finding":"NKG2A (~43 kDa) is covalently associated with CD94 on the surface of NK cells. Cell surface expression of NKG2A requires association with CD94 (as glycosylation patterns characteristic of mature proteins are found only in NKG2A associated with CD94). NKG2A contains two ITIMs consistent with its inhibitory function.","method":"Co-immunoprecipitation, glycosylation analysis, NK clone functional analysis","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — biochemical co-IP with glycosylation maturation evidence; replicated independently","pmids":["9034158"],"is_preprint":false},{"year":1997,"finding":"CD94 ligation on group A (activating) NK clones induces activation of intracellular PTKs (lck and ZAP-70), phospholipase C, and PI3-kinase. In contrast, CD94 ligation on group B (inhibitory) clones inhibits FcR-induced tyrosine phosphorylations of ZAP-70 and PLC-γ2, formation of phospho-zeta/ZAP-70 complexes, and release of inositol phosphates.","method":"Biochemical signaling assays, kinase activation assays, phosphorylation studies on sorted NK clones","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — multiple orthogonal signaling assays in single lab defining divergent signaling pathways","pmids":["8816383"],"is_preprint":false},{"year":1998,"finding":"HLA-E tetramers bind specifically to CD94/NKG2A, CD94/NKG2B, and CD94/NKG2C NK cell receptor complexes on transfectants, but not to immunoglobulin-family KIR receptors. Surface expression of HLA-E is sufficient to protect target cells from lysis by CD94/NKG2A+ NK-cell clones.","method":"HLA-E tetramer binding to transfectants, NK cytotoxicity assays with antibody blocking","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — tetramer binding with functional validation, replicated independently by multiple labs","pmids":["9486650"],"is_preprint":false},{"year":1998,"finding":"HLA-E is a major ligand for the CD94/NKG2A inhibitory receptor complex. Stabilization of HLA-E surface expression by appropriate HLA class I leader sequence peptides is sufficient to confer protection from NK lysis via CD94/NKG2A recognition. The inhibitory interaction is not mediated through Ig-SF KIRs or ILT2/LIR1.","method":"NK cytotoxicity assays, antibody blocking with anti-HLA-E, anti-CD94, anti-CD94/NKG2A mAbs; cold-target loading with leader peptides","journal":"Proceedings of the National Academy of Sciences","confidence":"High","confidence_rationale":"Tier 2 / Strong — functional reconstitution with blocking antibodies, replicated by multiple labs","pmids":["9560253"],"is_preprint":false},{"year":1998,"finding":"CD94/NKG2C (activating receptor) noncovalently associates with DAP12, a membrane receptor containing an ITAM. Efficient surface expression of CD94/NKG2C requires DAP12. Charged residues in the transmembrane domains of DAP12 and NKG2C are necessary for this interaction.","method":"Co-immunoprecipitation, transfection with wild-type and mutant constructs, surface expression analysis","journal":"Immunity","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — co-IP with transmembrane domain mutagenesis demonstrating requirement for charged residues","pmids":["9655483"],"is_preprint":false},{"year":1998,"finding":"Specific engagement of CD94/NKG2-A by HLA-E induces tyrosine phosphorylation of the NKG2-A subunit and SHP-1 recruitment. These early biochemical events were also detected upon NK cell interaction with HLA-E+ transfectants and were prevented by anti-HLA class I mAb. In RBL-2H3 transfectants, CD94/NKG2-A cross-linking promoted NKG2-A tyrosine phosphorylation, SHP-1 co-precipitation, and inhibition of Fc-εRI-triggered secretion.","method":"Tyrosine phosphorylation assays, SHP-1 co-immunoprecipitation, RBL-2H3 transfection reconstitution, cytotoxicity assays","journal":"European journal of immunology","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — reconstitution in heterologous cell system plus primary NK cell data, multiple orthogonal methods","pmids":["9565368"],"is_preprint":false},{"year":1998,"finding":"Mouse NKG2A forms a CD94/NKG2A heterodimer that directly recognizes the nonclassical MHC class Ib molecule Qa-1(b) in a peptide (Qdm)-dependent manner, leading to inhibition of NK-mediated target cell lysis.","method":"Qa-1(b) tetramer binding, cloning of mouse NKG2A, NK cytotoxicity assays with peptide loading","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — direct tetramer binding assay with functional validation; mouse ortholog study","pmids":["9815261"],"is_preprint":false},{"year":1998,"finding":"The activating CD94/NKG2C receptor complex is formed by covalent association of CD94 with NKG2-C (Kp39). COS7 cotransfection of CD94 and NKG2-C confirmed the identity of Kp39 as NKG2-C. The P25 mAb triggered cytolytic activity via this complex in redirected killing.","method":"Co-immunoprecipitation, COS7 co-transfection, peptide mapping, RT-PCR on NK clones, redirected killing assay","journal":"European journal of immunology","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — reconstitution by co-transfection confirmed biochemical identity; multiple orthogonal methods","pmids":["9485212"],"is_preprint":false},{"year":1999,"finding":"The inhibitory CD94/NKG2-A receptor has a higher binding affinity for HLA-E than the activating CD94/NKG2-C receptor. Both receptors show very fast association and dissociation kinetics. Recognition of HLA-E by both receptors is peptide-dependent, and binding affinity of peptide-HLA-E complexes directly correlates with triggering of NK cell responses.","method":"Surface plasmon resonance (BIAcore) with soluble recombinant HLA-E and soluble CD94/NKG2-A and CD94/NKG2-C proteins; NK functional assays","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro binding kinetics with purified recombinant proteins correlated with functional assays in single lab","pmids":["10428963"],"is_preprint":false},{"year":1999,"finding":"The crystal structure of the CD94 extracellular domain reveals a unique C-type lectin fold variation in which the second alpha-helix is replaced by a loop, the putative carbohydrate-binding site is altered, and the Ca2+-binding site appears nonfunctional. The CD94 dimer observed in the crystal has an extensive hydrophobic interface and reveals a putative ligand-binding region for HLA-E, suggesting how NKG2 interacts with CD94.","method":"X-ray crystallography at 2.6 Å resolution","journal":"Immunity","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure at 2.6 Å; single study but high-quality structural method","pmids":["10023772"],"is_preprint":false},{"year":1999,"finding":"CD94/NKG2-A inhibitory complex blocks CD16-triggered Syk kinase activation and tyrosine phosphorylation of the CD16 zeta subunit. It also inhibits ERK activation by blocking Shc tyrosine phosphorylation and Shc/Grb-2 complex formation downstream of CD16.","method":"Kinase activity assays, co-immunoprecipitation, western blotting for phosphorylation, ERK activation assays","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — multiple orthogonal signaling assays defining inhibitory signaling pathway","pmids":["10358164"],"is_preprint":false},{"year":1999,"finding":"Mouse CD94/NKG2C and CD94/NKG2E also bind to Qa-1(b), and these are activating receptors based on cytoplasmic domain features. An anti-NKG2 blocking mAb demonstrated that CD94/NKG2 molecules are the only Qa-1(b) receptors on NK cells.","method":"Cloning and expression, Qa-1(b) binding assays, anti-NKG2 blocking mAb, RT-PCR","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 2 / Moderate — receptor cloning with direct Qa-1(b) binding demonstrated and blocking mAb validation","pmids":["10601355"],"is_preprint":false},{"year":1998,"finding":"HLA-E is expressed on the surface of trophoblast cells and the majority of decidual NK cells bind HLA-E tetramers; this binding is inhibited by anti-CD94 mAb. The overall functional consequence of CD94/NKG2 interaction with HLA-E on decidual NK cells is inhibition of cytotoxicity.","method":"HLA-E tetramer binding, flow cytometry, anti-CD94 blocking, cytotoxicity assays with decidual NK cells","journal":"European journal of immunology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — tetramer binding with anti-CD94 blocking and functional cytotoxicity assays","pmids":["10898498"],"is_preprint":false},{"year":2002,"finding":"CD94/NKG2A receptors continuously recycle between the cell surface and intracellular endosomal compartments in an active process requiring energy and the cytoskeleton. CD94/NKG2A uses a distinct recycling compartment from transferrin receptor. CD94/NKG2A internalization is independent of ligand cross-linking or functional ITIM motifs.","method":"Flow cytometry, confocal microscopy, biochemical fractionation, transfection of wild-type and ITIM-mutant CD94/NKG2A in RBL-2H3 cells","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (flow, confocal, biochemistry) with mutagenesis in reconstituted system","pmids":["12444112"],"is_preprint":false},{"year":2006,"finding":"CD94/NKG2A engagement prevents NK cell activation by disrupting the actin network and excluding lipid rafts at the inhibitory NK immunological synapse (iNKIS). This involves SHP-1 recruitment and activation, leading to dephosphorylation of Vav1 and ezrin-radixin-moesin (ERM) proteins. Actin polymerization inhibition abolished lipid raft exclusion at iNKIS, whereas cholesterol depletion did not affect actin disruption.","method":"Confocal microscopy, fluorescence imaging of immunological synapse, phosphorylation assays (Vav1, ERM), pharmacological inhibition of actin polymerization and cholesterol depletion","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (imaging + biochemistry + pharmacology) defining mechanism at immunological synapse","pmids":["16951318"],"is_preprint":false},{"year":2007,"finding":"Crystal structure of CD94-NKG2A heterodimer at 2.5 Å resolution reveals an asymmetric dimer interface despite structural homology between the two subunits, providing structural basis for preferred heterodimeric assembly. Extensive mutagenesis studies on HLA-E and CD94-NKG2A establish that the invariant CD94 chain plays a dominant role in interacting with HLA-E compared to the variable NKG2 chain.","method":"X-ray crystallography at 2.5 Å, site-directed mutagenesis of HLA-E and CD94-NKG2A interface residues","journal":"Immunity","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure with extensive mutagenesis validation; independently confirmed by two contemporaneous structural studies","pmids":["18083576"],"is_preprint":false},{"year":2008,"finding":"Crystal structure of CD94-NKG2A in complex with HLA-E (bound to HLA-G leader peptide) shows that the CD94 subunit dominates the interaction with HLA-E, while NKG2A is more peripheral to the interface. CD94 dominates peptide-mediated contacts with poor surface and chemical complementarity. The interaction shows little conformational change upon ligation ('lock and key' mode). Mutagenesis data confirmed the CD94-NKG2A-HLA-E interface.","method":"X-ray crystallography of ternary complex, mutagenesis at CD94-NKG2A-HLA-E interface","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure of ternary complex with mutagenesis validation; independently confirmed by contemporaneous structural study","pmids":["18332182"],"is_preprint":false},{"year":2008,"finding":"Crystal structure of NKG2A/CD94/HLA-E at 4.4 Å resolution reveals that the C-terminal region of the bound peptide interacts entirely with CD94 (the invariant component). Residues 167-170 of NKG2A/C (at the CD94 heterodimer interface, not contacting HLA-E directly) account for the ~6-fold higher affinity of inhibitory NKG2A/CD94 compared to activating NKG2C/CD94 for HLA-E.","method":"X-ray crystallography at 4.4 Å, comparative analysis with NKG2C structure, evolutionary analysis","journal":"Proceedings of the National Academy of Sciences","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure with mechanistic insight; consistent with contemporaneous structural work","pmids":["18448674"],"is_preprint":false},{"year":2008,"finding":"Subtle changes in peptide conformation (without changes in HLA-E heavy chain conformation) profoundly affect CD94-NKG2 receptor recognition of HLA-E. Structures of HLA-E with HLA-Cw*07 leader peptide (low affinity) versus HLA-G*01 leader peptide (high affinity) at 2.5 Å show allotypic variations produce subtle differences in peptide conformation within the binding groove.","method":"X-ray crystallography of two HLA-E/peptide complexes at 2.5 Å resolution, compared with CD94-NKG2 binding data","journal":"Journal of molecular biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structures at 2.5 Å with direct binding comparison; single lab","pmids":["18339401"],"is_preprint":false},{"year":2004,"finding":"Both CD94/NKG2A (inhibitory) and CD94/NKG2C (activating) bind the top of HLA-E alpha1/alpha2 domain using mostly shared but partly distinct sets of HLA-E residues. Two HLA-E mutations (D69A and H155A) selectively abrogated binding to CD94/NKG2A but not to CD94/NKG2C, identifying differential contact residues.","method":"Alanine-scanning mutagenesis of HLA-E with binding assays to soluble CD94/NKG2A and CD94/NKG2C","journal":"European journal of immunology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — systematic alanine scanning of the HLA-E surface with both inhibitory and activating receptor binding assays","pmids":["14971033"],"is_preprint":false},{"year":2000,"finding":"CD69-triggered ERK activation and cell degranulation are negatively regulated by co-engagement of the CD94/NKG2-A inhibitory receptor. CD94/NKG2-A suppresses CD69-triggered degranulation by inhibiting ERK activation in RBL transfectants expressing both receptors.","method":"RBL-2H3 transfectants expressing CD69 and CD94/NKG2-A, ERK activation assays, degranulation assays, cytotoxicity assays","journal":"European journal of immunology","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — reconstituted system (RBL transfectants) with multiple signaling and functional readouts","pmids":["10671222"],"is_preprint":false},{"year":1999,"finding":"HLA-E engagement of CD94/NKG2 complex on porcine endothelial cell transfectants leads to phosphorylation of the CD94/NKG2 complex and recruitment of SHP-1, mediating inhibition of xenoreactive human NK cells. In contrast, HLA-G inhibits NK cells through a CD94/NKG2-independent pathway without SHP-1 recruitment.","method":"Anti-CD94 blocking, SHP-1 co-immunoprecipitation, phosphorylation assays, xenogeneic cytotoxicity assays","journal":"Journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — SHP-1 co-IP and phosphorylation data with functional cytotoxicity assays; single lab","pmids":["10570324"],"is_preprint":false},{"year":2003,"finding":"Hsp70 protein and its C-terminal domain (Hsp70C) bind specifically to CD94 on NK cells (YT cell line). CD94-specific antibody completely abrogated Hsp70 binding. Competition assays with excess unlabeled Hsp70 (not unrelated GST) confirmed specific, concentration-dependent binding.","method":"Immunofluorescence binding studies, antibody blocking with anti-CD94 mAb, competition assays","journal":"Biological chemistry","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — binding assays on cell line with antibody blocking; single lab, no reconstitution or structural validation","pmids":["12675520"],"is_preprint":false},{"year":2011,"finding":"CD94 is essential for resistance of C57BL/6 mice to ectromelia virus (mousepox). Ectromelia virus-infected cells expressing Qa-1(b) are specifically recognized by the activating receptor CD94-NKG2E, and CD94-deficient mice are highly susceptible to mousepox.","method":"CD94-deficient mouse infection model, NK cell depletion, genetic epistasis, survival/viral load assays","journal":"Immunity","confidence":"High","confidence_rationale":"Tier 2 / Moderate — gene-targeted KO mouse with defined viral susceptibility phenotype and receptor-ligand specificity established","pmids":["21439856"],"is_preprint":false},{"year":2010,"finding":"CD94-deficient mice develop NK cells normally that efficiently kill NK-susceptible targets. Lack of CD94 receptors (and associated NKG2A, NKG2C, NKG2E) does not alter control of mouse CMV, LCMV, vaccinia virus, or Listeria monocytogenes, indicating CD94 is dispensable for NK cell development, education, and many innate immune functions.","method":"Gene-targeted CD94-deficient mouse, NK cell development and functional assays, viral and bacterial infection challenge models","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 2 / Moderate — gene-targeted KO with multiple defined negative phenotypic readouts; rigorous loss-of-function approach","pmids":["21151939"],"is_preprint":false},{"year":2005,"finding":"CD94/NKG2C is coupled to DAP12 (KARAP) in CD8+ T cells, and specific engagement of CD94/NKG2C triggers cytotoxicity, cytokine production, IL-2Rα expression, and proliferative responses in CD94/NKG2C+ T cell clones. Anti-CD94 co-precipitation confirmed DAP12 association in T cells.","method":"Co-immunoprecipitation of DAP12 with anti-CD94, functional assays (cytotoxicity, cytokine production, proliferation) in T cell clones with selective receptor engagement","journal":"European journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP confirmed DAP12 association; multiple functional readouts in T cell clones; single lab","pmids":["15940674"],"is_preprint":false},{"year":2002,"finding":"Mouse Nkg2a is stochastically and monoallelically expressed, similar to Ly49 genes. DBA/2J mice are naturally CD94-deficient and do not express surface CD94/NKG2A receptors. CD94-deficient neonatal NK cells are self-tolerant, indicating self-tolerance of neonatal NK cells cannot be solely attributed to CD94/NKG2A expression.","method":"Allele-specific expression analysis, DBA/2J strain characterization, flow cytometry","journal":"Proceedings of the National Academy of Sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic analysis with flow cytometric validation; naturally occurring KO strain provides loss-of-function evidence","pmids":["11782535"],"is_preprint":false},{"year":2021,"finding":"NKG2A genetic ablation in dams mated with wild-type males causes suboptimal maternal vascular responses in pregnancy, perturbed placental gene expression, reduced fetal weight, and abnormal fetal brain development. These results establish that the HLA-B→HLA-E→NKG2A pathway contributes to healthy pregnancy via NK cell education.","method":"NKG2A gene-targeted KO mouse crossed with wild-type males, vascular/placental/fetal phenotyping, genome-wide association study in humans for validation","journal":"Immunity","confidence":"High","confidence_rationale":"Tier 2 / Strong — gene-targeted KO with defined pregnancy phenotypes plus human GWAS validation across multiple orthogonal approaches","pmids":["33887202"],"is_preprint":false},{"year":2005,"finding":"CD94/NKG2A receptors move freely within the plasma membrane, accumulate at the site of contact with ligand-bearing target cells, and continuously recycle from the cell surface through endosomal compartments in a process requiring energy and the cytoskeleton. Lipid raft marker cholera toxin B is excluded from CD94/NKG2A-enriched contact sites; methylcyclodextrin does not interfere with CD94/NKG2A accumulation at contact sites.","method":"FRAP, live-cell fluorescence microscopy, pharmacological perturbations (cytoskeleton inhibitors, cholesterol depletion), confocal microscopy","journal":"Molecular immunology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — live imaging (FRAP), confocal, and pharmacological approaches establishing subcellular trafficking with functional context","pmids":["15607803"],"is_preprint":false},{"year":2002,"finding":"CD94-NKG2A up-regulation on antiviral CD8+ T cells during acute polyoma virus infection is responsible for down-regulating their antigen-specific cytotoxicity during viral clearance and virus-induced oncogenesis.","method":"Murine polyoma virus infection model, flow cytometry of CD94/NKG2A expression on antigen-specific T cells, antibody blocking of CD94, cytotoxicity assays","journal":"Nature immunology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — in vivo mouse model with antibody blocking to establish causal role of CD94/NKG2A in CTL inhibition","pmids":["11812997"],"is_preprint":false},{"year":1998,"finding":"IL-15 induces de novo expression of CD94 by T cells responding to superantigens; the simultaneous expression of NKG2A (forming functional CD94/NKG2A) is confined to CD8+ cells. Expression of CD94/NKG2A led to impairment of allo-specific cytolytic activity, which was restored by anti-CD94 mAb.","method":"In vitro T cell stimulation with superantigens in presence of IL-15, flow cytometry, cytotoxicity assays with anti-CD94 mAb blocking","journal":"Proceedings of the National Academy of Sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional induction system with antibody-blocking demonstration of causal role; single lab","pmids":["9448304"],"is_preprint":false},{"year":1999,"finding":"TGF-β induces expression of CD94/NKG2A in T cells responding to bacterial superantigens. Expression preferentially occurs at low TGF-β concentrations, NKG2A expression is mostly confined to CD8+ cells, and mAb-mediated cross-linking of CD94/NKG2A impairs T cell triggering via CD3.","method":"In vitro stimulation of T cells with superantigens + TGF-β, flow cytometry, redirected killing assay","journal":"European journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional assays linking TGF-β induction to inhibitory receptor expression and function; single lab","pmids":["9933082"],"is_preprint":false},{"year":2024,"finding":"LAG-3 sustains CD94/NKG2A expression on exhausted CD8 T cells by maintaining TOX expression. A LAG-3-dependent circuit generates a CD94/NKG2+ subset of exhausted T cells with enhanced cytotoxicity mediated by recognition of the stress ligand Qa-1b (and HLA-E in humans).","method":"LAG-3 genetic deletion during chronic LCMV infection, single-cell analysis, functional cytotoxicity assays, Qa-1b blocking, TOX expression analysis","journal":"Cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO with mechanistic epistasis (LAG-3→TOX→CD94/NKG2A→Qa-1b recognition), multiple orthogonal methods","pmids":["39121847"],"is_preprint":false},{"year":2020,"finding":"NKG2A/CD94 was identified as a cognate receptor for HLA-G*01:01, with binding affinity dependent on the amino acid composition of the HLA-G heavy chain (HLA-G*01:04 shows highest affinity, while HLA-G*01:03 and HLA-G*01:01 show lower binding).","method":"Ligand-based receptor capture on living NK cells using sHLA-G*01:01 coupled to TriCEPS followed by mass spectrometry; reciprocal validation with recombinant soluble NKG2A/CD94 targeting HLA-G-expressing K562 cells","journal":"International journal of molecular sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — two orthogonal binding methods (TriCEPS capture + reciprocal recombinant protein binding); single lab","pmids":["32575403"],"is_preprint":false},{"year":2023,"finding":"Among 16 common classical HLA class I signal peptide variants, only 6 can be efficiently processed to generate epitopes that enable CD94/NKG2 engagement ('functional SPs'). The single functional HLA-B SP (HLA-B/-21M) confers the lowest receptor recognition by CD94/NKG2A/C despite inducing high HLA-E expression, because it competes with other SPs and reduces overall CD94/NKG2-HLA-E engagement.","method":"Systematic quantitative functional assays measuring HLA-E surface expression and CD94/NKG2A/C receptor engagement for all 16 common SP variants; competitive peptide loading assays","journal":"Nature immunology","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — systematic quantitative approach across all common HLA-B SP variants with multiple orthogonal functional assays","pmids":["37264229"],"is_preprint":false},{"year":1998,"finding":"The human CD94 gene contains six exons separated by five introns. The carbohydrate-recognition domain (CRD) is encoded by three exons. Transcription initiation is heterogeneous but restricted to a 60 bp region within a putative initiator element. CD94 is closely related to group V of C-type lectins based on intron position conservation within the CRD.","method":"Genomic cloning, exon-intron structure determination, primer extension, S1 nuclease protection assays","journal":"Immunogenetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct genomic characterization with transcription start site mapping; single lab","pmids":["9472066"],"is_preprint":false}],"current_model":"CD94 (KLRD1) functions as the invariant subunit of heterodimeric NK and T cell receptors by forming disulfide-bonded complexes with NKG2 family members (NKG2A/B forming inhibitory receptors via ITIM-mediated SHP-1 recruitment; NKG2C/E forming activating receptors via DAP12/ITAM association); the CD94 subunit dominates recognition of the non-classical MHC class I molecule HLA-E (and mouse Qa-1b), which presents leader sequence peptides from other HLA class I molecules, with CD94-NKG2A having higher HLA-E affinity than CD94-NKG2C, and inhibitory signaling proceeding through NKG2A ITIM phosphorylation, SHP-1 recruitment, and downstream disruption of the actin network and lipid raft organization at the immunological synapse to suppress NK and CTL cytotoxic effector functions."},"narrative":{"mechanistic_narrative":"KLRD1 (CD94) is the invariant subunit of a family of heterodimeric NK- and T-cell receptors that survey cells for the non-classical MHC class I molecule HLA-E (mouse Qa-1b), thereby coupling detection of overall MHC class I integrity to control of cytotoxic effector function [PMID:8943374, PMID:9486650, PMID:9815261]. CD94 is a C-type-lectin-fold glycoprotein whose structure is atypical — the second alpha-helix is replaced by a loop, the carbohydrate-binding site is altered, and the Ca2+ site is nonfunctional — and it assembles as a disulfide-linked dimer that pairs with NKG2 chains [PMID:10023772, PMID:9472066]. Disulfide-bonded heterodimers with NKG2A/B form inhibitory receptors carrying cytoplasmic ITIMs, whereas pairing with NKG2C/E generates activating receptors that lack ITIMs and instead associate noncovalently with the ITAM-bearing adaptor DAP12 through complementary transmembrane charged residues [PMID:8943374, PMID:9045931, PMID:9655483, PMID:9485212]. Crystal structures of CD94 alone, the CD94–NKG2A heterodimer, and the ternary CD94–NKG2A–HLA-E complex establish that the invariant CD94 chain dominates contact with HLA-E and its bound leader peptide in a lock-and-key mode, while the variable NKG2 chain lies peripheral; residues at the CD94–NKG2 interface (NKG2 167–170) account for the higher HLA-E affinity of the inhibitory CD94/NKG2A over the activating CD94/NKG2C [PMID:18083576, PMID:18332182, PMID:18448674]. HLA-E recognition is strictly peptide-dependent, and subtle differences in the conformation of HLA class I leader peptides — only a subset of which are efficiently processed into functional epitopes — tune receptor engagement and the resulting NK response [PMID:10428963, PMID:18339401, PMID:37264229]. Engagement of CD94/NKG2A by HLA-E triggers NKG2A ITIM tyrosine phosphorylation and SHP-1 recruitment, which blocks activation-receptor signaling (Syk/ZAP-70, Shc/Grb-2, ERK) and disrupts the actin network and lipid raft organization at the inhibitory immunological synapse, suppressing cytotoxicity [PMID:9565368, PMID:10358164, PMID:16951318]. Through this inhibitory axis, CD94/NKG2A restrains NK and antigen-specific CD8+ T-cell cytotoxicity in viral infection and contributes, via the HLA-B→HLA-E→NKG2A education pathway, to healthy pregnancy [PMID:33887202, PMID:11812997, PMID:39121847], while CD94/NKG2E serves as an activating receptor required for resistance to ectromelia virus [PMID:21439856].","teleology":[{"year":1996,"claim":"Establishing that CD94 is not a stand-alone receptor but the shared subunit of a family of heterodimers explained how a single invariant chain could give rise to both inhibitory and activating signaling.","evidence":"Co-immunoprecipitation, SDS-PAGE, and cytoplasmic-domain sequencing of CD94 paired with NKG2A/B/C/E, plus serological and functional discrimination of inhibitory vs stimulatory forms","pmids":["8943374","8955184"],"confidence":"High","gaps":["Did not identify the ligand of the heterodimers","Did not define the structural basis of preferential heterodimer assembly"]},{"year":1997,"claim":"Assigning the inhibitory function to the NKG2A/B ITIMs and showing CD94 is required for NKG2A surface maturation defined the molecular logic of the inhibitory receptor.","evidence":"Co-immunoprecipitation with anti-CD94, glycosylation maturation analysis, and ITIM sequence analysis on NK clones","pmids":["9045931","9034158"],"confidence":"High","gaps":["Did not identify the recruited phosphatase","Ligand still unknown"]},{"year":1996,"claim":"Demonstrating divergent intracellular signaling distinguished the two receptor classes functionally before their ligand was known.","evidence":"Kinase activation and phosphorylation assays on sorted activating vs inhibitory NK clones after CD94 ligation","pmids":["8816383"],"confidence":"High","gaps":["Performed by antibody ligation rather than physiological ligand","Phosphatase identity not yet pinned"]},{"year":1998,"claim":"Identification of HLA-E (and mouse Qa-1b) as the ligand revealed that CD94/NKG2 receptors monitor global MHC class I status by reading leader-peptide-loaded non-classical class I.","evidence":"HLA-E and Qa-1b tetramer binding to transfectants and NK clones, leader-peptide loading, and antibody-blocked cytotoxicity assays","pmids":["9486650","9560253","9815261"],"confidence":"High","gaps":["Did not quantify affinity differences between inhibitory and activating receptors","Atomic basis of recognition unresolved"]},{"year":1998,"claim":"Showing that the activating CD94/NKG2C complex requires DAP12 through transmembrane charged residues explained how the ITIM-less activating receptors deliver positive signals.","evidence":"Co-immunoprecipitation and transmembrane-domain mutagenesis with surface expression analysis; later extended to T cells","pmids":["9655483","15940674"],"confidence":"High","gaps":["DAP12 downstream signaling steps for this receptor not fully traced","T-cell co-IP evidence single lab (Medium)"]},{"year":1998,"claim":"Linking HLA-E engagement to NKG2A phosphorylation and SHP-1 recruitment provided the proximal biochemical mechanism of inhibition.","evidence":"Tyrosine phosphorylation and SHP-1 co-immunoprecipitation in primary NK cells and RBL-2H3 reconstitution","pmids":["9565368","10570324"],"confidence":"High","gaps":["Downstream substrates of SHP-1 not yet identified","Xenoreactive study (10570324) single lab, Medium confidence"]},{"year":1999,"claim":"Direct affinity measurement established that the inhibitory receptor binds HLA-E more strongly than the activating one, providing a kinetic basis for the dominance of inhibition.","evidence":"Surface plasmon resonance with soluble recombinant HLA-E and CD94/NKG2A vs CD94/NKG2C, correlated with NK functional assays","pmids":["10428963"],"confidence":"High","gaps":["Structural origin of the affinity difference not yet localized","Single-lab kinetic measurement"]},{"year":1999,"claim":"Defining the downstream inhibitory cascade showed how SHP-1 recruitment translates into blocked effector activation.","evidence":"Kinase, co-IP, and ERK activation assays demonstrating block of Syk, CD16-zeta phosphorylation, and Shc/Grb-2 complex formation; CD69-triggered ERK suppression in RBL transfectants","pmids":["10358164","10671222"],"confidence":"High","gaps":["Did not address synapse-level cytoskeletal effects","Reconstituted-system readouts"]},{"year":1999,"claim":"The first CD94 crystal structure revealed its atypical C-type lectin fold and a putative HLA-E binding surface, reframing CD94 as a lectin-like receptor that does not bind carbohydrate canonically.","evidence":"X-ray crystallography of the CD94 ectodomain at 2.6 Å","pmids":["10023772"],"confidence":"High","gaps":["Structure of the heterodimer and the ligand complex not yet solved","Functional carbohydrate/Ca2+ sites inferred, not tested"]},{"year":2004,"claim":"Mutagenesis mapping showed inhibitory and activating receptors engage largely shared but partly distinct HLA-E surfaces, giving the first explanation for differential recognition.","evidence":"Alanine-scanning mutagenesis of HLA-E with binding to soluble CD94/NKG2A and CD94/NKG2C","pmids":["14971033"],"confidence":"High","gaps":["Did not resolve which subunit contributes which contacts atomically"]},{"year":2008,"claim":"Structures of the heterodimer and the ternary CD94–NKG2A–HLA-E complex established that the invariant CD94 chain dominates ligand contact and that NKG2 interface residues, not direct HLA-E contacts, set affinity differences.","evidence":"X-ray crystallography of CD94–NKG2A (2.5 Å), the ternary complex, and HLA-E/peptide structures, with interface mutagenesis","pmids":["18083576","18332182","18448674","18339401"],"confidence":"High","gaps":["Did not connect binding to dynamics of signaling at the synapse"]},{"year":2006,"claim":"Imaging the inhibitory synapse connected SHP-1 activity to physical disruption of the effector machinery, explaining how inhibition aborts killing.","evidence":"Confocal imaging, Vav1/ERM phosphorylation assays, and pharmacological actin and cholesterol perturbations at the inhibitory NK immunological synapse; earlier trafficking/recycling studies","pmids":["16951318","12444112","15607803"],"confidence":"High","gaps":["Did not fully resolve order of actin disruption vs raft exclusion in vivo","Trafficking compartment identity partly defined"]},{"year":2011,"claim":"Loss-of-function mouse genetics established the physiological roles and limits of CD94, showing it is dispensable for development yet required for the activating CD94/NKG2E response to a poxvirus.","evidence":"CD94-deficient and naturally CD94-deficient (DBA/2J) mouse models with viral and bacterial challenge, NK development, and tolerance assays","pmids":["21439856","21151939","11782535"],"confidence":"High","gaps":["Redundant inhibitory pathways masking phenotypes not fully mapped","Allelic expression regulation (Medium) needs mechanism"]},{"year":2002,"claim":"Inducible expression on CD8+ T cells demonstrated that the inhibitory receptor restrains antigen-specific CTL responses, extending CD94 biology beyond NK cells.","evidence":"In vivo polyoma virus infection with CD94/NKG2A blockade; IL-15- and TGF-β-driven induction of CD94/NKG2A on superantigen-stimulated T cells with functional blocking","pmids":["11812997","9448304","9933082"],"confidence":"High","gaps":["Transcriptional control of induction defined only by cytokine inputs (Medium)","Consequences for tumor immunity not fully addressed here"]},{"year":2021,"claim":"Pregnancy and exhaustion models linked the HLA-E→NKG2A axis to NK-cell education in reproduction and to a LAG-3/TOX-dependent cytotoxic subset of exhausted T cells, broadening physiological context.","evidence":"NKG2A-targeted KO crossed to wild-type males with placental/fetal phenotyping plus human GWAS; LAG-3 deletion in chronic LCMV with single-cell, TOX, and Qa-1b functional analysis","pmids":["33887202","39121847"],"confidence":"High","gaps":["Mechanism linking NK education to vascular outcomes not fully resolved","Human translation of exhaustion circuit inferred"]},{"year":2023,"claim":"Systematic analysis of leader-peptide variants showed that only a subset of HLA signal peptides are efficiently processed into functional CD94/NKG2 epitopes, and competition among them tunes receptor engagement.","evidence":"Quantitative HLA-E surface expression and CD94/NKG2A/C engagement assays across 16 common signal-peptide variants with competitive loading; HLA-G allotype binding by ligand capture/reciprocal recombinant assays","pmids":["37264229","32575403"],"confidence":"High","gaps":["Population-level consequences of variant repertoire not addressed","HLA-G recognition single-lab (Medium)"]},{"year":null,"claim":"How CD94/NKG2 receptor surface levels, recycling, and ligand competition are integrated to set NK and T-cell activation thresholds in human disease and therapy remains incompletely defined.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No timeline evidence on regulation of receptor turnover during chronic human disease","Therapeutic modulation of the axis not characterized in the corpus"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0001618","term_label":"virus receptor activity","supporting_discovery_ids":[5,9,36]},{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[4,8,13]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,7,18]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[8,17,23]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[3,16,31]},{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[16,31]}],"pathway":[{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[5,8,26,32]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[4,8,13]}],"complexes":["CD94/NKG2A inhibitory receptor","CD94/NKG2C-DAP12 activating receptor","CD94/NKG2E activating receptor"],"partners":["NKG2A","NKG2C","NKG2E","DAP12","HLA-E","SHP-1","HSP70"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q13241","full_name":"Natural killer cells antigen CD94","aliases":["KP43","Killer cell lectin-like receptor subfamily D member 1","NK cell receptor"],"length_aa":179,"mass_kda":20.5,"function":"Immune receptor involved in self-nonself discrimination. In complex with KLRC1 or KLRC2 on cytotoxic and regulatory lymphocyte subsets, recognizes non-classical major histocompatibility (MHC) class Ib molecule HLA-E loaded with self-peptides derived from the signal sequence of classical MHC class Ia and non-classical MHC class Ib molecules (PubMed:10023772, PubMed:18064301, PubMed:18083576, PubMed:37264229, PubMed:9486650, PubMed:9754572). Enables cytotoxic cells to monitor the expression of MHC class I molecules in healthy cells and to tolerate self (PubMed:12387742, PubMed:18064301, PubMed:9430220). Primarily functions as a ligand binding subunit as it lacks the capacity to signal KLRD1-KLRC1 acts as an immune inhibitory receptor. Key inhibitory receptor on natural killer (NK) cells that regulates their activation and effector functions (PubMed:30860984, PubMed:9430220, PubMed:9485206, PubMed:9486650). Dominantly counteracts T cell receptor signaling on a subset of memory/effector CD8-positive T cells as part of an antigen-driven response to avoid autoimmunity (PubMed:12387742). On intraepithelial CD8-positive gamma-delta regulatory T cells triggers TGFB1 secretion, which in turn limits the cytotoxic programming of intraepithelial CD8-positive alpha-beta T cells, distinguishing harmless from pathogenic antigens (PubMed:18064301). In HLA-E-rich tumor microenvironment, acts as an immune inhibitory checkpoint and may contribute to progressive loss of effector functions of NK cells and tumor-specific T cells, a state known as cell exhaustion (PubMed:30503213, PubMed:30860984). Upon HLA-E-peptide binding, transmits intracellular signals through KLRC1 immunoreceptor tyrosine-based inhibition motifs (ITIMs) by recruiting INPP5D/SHIP-1 and INPPL1/SHIP-2 tyrosine phosphatases to ITIMs, and ultimately opposing signals transmitted by activating receptors through dephosphorylation of proximal signaling molecules (PubMed:12165520, PubMed:9485206) KLRD1-KLRC2 acts as an immune activating receptor (PubMed:15940674, PubMed:9655483). On cytotoxic lymphocyte subsets recognizes HLA-E loaded with signal sequence-derived peptides from non-classical MHC class Ib HLA-G molecules, likely playing a role in the generation and effector functions of adaptive NK cells and in maternal-fetal tolerance during pregnancy (PubMed:30134159, PubMed:9754572). Regulates the effector functions of terminally differentiated cytotoxic lymphocyte subsets, and in particular may play a role in adaptive NK cell response to viral infection (PubMed:20952657, PubMed:21825173). Upon HLA-E-peptide binding, transmits intracellular signals via the adapter protein TYROBP/DAP12, triggering the phosphorylation of proximal signaling molecules and cell activation (PubMed:15940674, PubMed:9655483) (Microbial infection) Viruses like human cytomegalovirus have evolved an escape mechanism whereby virus-induced down-regulation of host MHC class I molecules is coupled to the binding of viral peptides to HLA-E, restoring HLA-E expression and inducing HLA-E-dependent NK cell immune tolerance to infected cells. Recognizes HLA-E in complex with human cytomegalovirus UL40-derived peptide (VMAPRTLIL) and inhibits NK cell cytotoxicity (Microbial infection) May recognize HLA-E in complex with HIV-1 gag/Capsid protein p24-derived peptide (AISPRTLNA) on infected cells and may inhibit NK cell cytotoxicity, a mechanism that allows HIV-1 to escape immune recognition (Microbial infection) Upon SARS-CoV-2 infection, may contribute to functional exhaustion of cytotoxic NK cells and CD8-positive T cells (PubMed:32859121). On NK cells, may recognize HLA-E in complex with SARS-CoV-2 S/Spike protein S1-derived peptide (LQPRTFLL) expressed on the surface of lung epithelial cells, inducing NK cell exhaustion and dampening antiviral immune surveillance (PubMed:32859121)","subcellular_location":"Cell membrane","url":"https://www.uniprot.org/uniprotkb/Q13241/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/KLRD1","classification":"Not Classified","n_dependent_lines":2,"n_total_lines":1208,"dependency_fraction":0.0016556291390728477},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/KLRD1","total_profiled":1310},"omim":[{"mim_id":"611817","title":"KILLER CELL LECTIN-LIKE RECEPTOR, SUBFAMILY K, MEMBER 1; KLRK1","url":"https://www.omim.org/entry/611817"},{"mim_id":"606783","title":"C-TYPE LECTIN DOMAIN FAMILY 1, MEMBER B; CLEC1B","url":"https://www.omim.org/entry/606783"},{"mim_id":"606782","title":"C-TYPE LECTIN DOMAIN FAMILY 1, MEMBER A; CLEC1A","url":"https://www.omim.org/entry/606782"},{"mim_id":"604274","title":"KILLER CELL LECTIN-LIKE RECEPTOR A1, PSEUDOGENE; KLRA1P","url":"https://www.omim.org/entry/604274"},{"mim_id":"602894","title":"KILLER CELL LECTIN-LIKE RECEPTOR, SUBFAMILY D, MEMBER 1; KLRD1","url":"https://www.omim.org/entry/602894"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"lymphoid tissue","ntpm":16.2}],"url":"https://www.proteinatlas.org/search/KLRD1"},"hgnc":{"alias_symbol":[],"prev_symbol":["CD94"]},"alphafold":{"accession":"Q13241","domains":[{"cath_id":"3.10.100.10","chopping":"67-178","consensus_level":"high","plddt":96.6721,"start":67,"end":178},{"cath_id":"1.20.5","chopping":"2-38","consensus_level":"medium","plddt":80.9357,"start":2,"end":38}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q13241","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q13241-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q13241-F1-predicted_aligned_error_v6.png","plddt_mean":87.56},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=KLRD1","jax_strain_url":"https://www.jax.org/strain/search?query=KLRD1"},"sequence":{"accession":"Q13241","fasta_url":"https://rest.uniprot.org/uniprotkb/Q13241.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q13241/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q13241"}},"corpus_meta":[{"pmid":"9486650","id":"PMC_9486650","title":"HLA-E binds to natural killer cell receptors CD94/NKG2A, B and C.","date":"1998","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/9486650","citation_count":1823,"is_preprint":false},{"pmid":"9560253","id":"PMC_9560253","title":"HLA-E is a major ligand for the natural killer inhibitory receptor CD94/NKG2A.","date":"1998","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/9560253","citation_count":844,"is_preprint":false},{"pmid":"9655483","id":"PMC_9655483","title":"Association of DAP12 with activating CD94/NKG2C NK cell receptors.","date":"1998","source":"Immunity","url":"https://pubmed.ncbi.nlm.nih.gov/9655483","citation_count":432,"is_preprint":false},{"pmid":"9815261","id":"PMC_9815261","title":"Mouse CD94/NKG2A is a natural killer cell receptor for the nonclassical major histocompatibility complex (MHC) class I molecule Qa-1(b).","date":"1998","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/9815261","citation_count":357,"is_preprint":false},{"pmid":"16384928","id":"PMC_16384928","title":"Expansion of CD94/NKG2C+ NK cells in response to human cytomegalovirus-infected fibroblasts.","date":"2005","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/16384928","citation_count":356,"is_preprint":false},{"pmid":"8943374","id":"PMC_8943374","title":"Human natural killer cell receptors involved in MHC class I recognition are disulfide-linked heterodimers of CD94 and NKG2 subunits.","date":"1996","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/8943374","citation_count":352,"is_preprint":false},{"pmid":"10428963","id":"PMC_10428963","title":"Kinetics and peptide dependency of the binding of the inhibitory NK receptor CD94/NKG2-A and the activating receptor CD94/NKG2-C to HLA-E.","date":"1999","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/10428963","citation_count":301,"is_preprint":false},{"pmid":"9933109","id":"PMC_9933109","title":"The ILT2(LIR1) and CD94/NKG2A NK cell receptors respectively recognize HLA-G1 and HLA-E molecules co-expressed on target cells.","date":"1999","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/9933109","citation_count":300,"is_preprint":false},{"pmid":"10898498","id":"PMC_10898498","title":"HLA-E is expressed on trophoblast and interacts with CD94/NKG2 receptors on decidual NK cells.","date":"2000","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/10898498","citation_count":290,"is_preprint":false},{"pmid":"36706761","id":"PMC_36706761","title":"Immune checkpoint HLA-E:CD94-NKG2A mediates evasion of circulating tumor cells from NK cell surveillance.","date":"2023","source":"Cancer cell","url":"https://pubmed.ncbi.nlm.nih.gov/36706761","citation_count":272,"is_preprint":false},{"pmid":"9045931","id":"PMC_9045931","title":"The CD94 and NKG2-A C-type lectins covalently assemble to form a natural killer cell inhibitory receptor for HLA class I molecules.","date":"1997","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/9045931","citation_count":251,"is_preprint":false},{"pmid":"8046333","id":"PMC_8046333","title":"Human natural killer cell receptors for HLA-class I molecules. Evidence that the Kp43 (CD94) molecule functions as receptor for HLA-B alleles.","date":"1994","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/8046333","citation_count":223,"is_preprint":false},{"pmid":"9034158","id":"PMC_9034158","title":"NKG2A complexed with CD94 defines a novel inhibitory natural killer cell receptor.","date":"1997","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/9034158","citation_count":214,"is_preprint":false},{"pmid":"19897577","id":"PMC_19897577","title":"CD94 surface density identifies a functional intermediary between the CD56bright and CD56dim human NK-cell subsets.","date":"2009","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/19897577","citation_count":197,"is_preprint":false},{"pmid":"9448304","id":"PMC_9448304","title":"HLA class I-specific inhibitory receptors in human T lymphocytes: interleukin 15-induced expression of CD94/NKG2A in superantigen- or alloantigen-activated CD8+ T cells.","date":"1998","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/9448304","citation_count":194,"is_preprint":false},{"pmid":"18332182","id":"PMC_18332182","title":"CD94-NKG2A recognition of human leukocyte antigen (HLA)-E bound to an HLA class I leader sequence.","date":"2008","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/18332182","citation_count":193,"is_preprint":false},{"pmid":"12778484","id":"PMC_12778484","title":"The natural killer cell-mediated killing of autologous dendritic cells is confined to a cell subset expressing CD94/NKG2A, but lacking inhibitory killer Ig-like receptors.","date":"2003","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/12778484","citation_count":193,"is_preprint":false},{"pmid":"10447727","id":"PMC_10447727","title":"CD69 is a stimulatory receptor for natural killer cell and its cytotoxic effect is blocked by CD94 inhibitory receptor.","date":"1999","source":"Immunology","url":"https://pubmed.ncbi.nlm.nih.gov/10447727","citation_count":185,"is_preprint":false},{"pmid":"18448674","id":"PMC_18448674","title":"Structural basis for NKG2A/CD94 recognition of HLA-E.","date":"2008","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/18448674","citation_count":180,"is_preprint":false},{"pmid":"12438449","id":"PMC_12438449","title":"IFN-gamma protects short-term ovarian carcinoma cell lines from CTL lysis via a CD94/NKG2A-dependent mechanism.","date":"2002","source":"The Journal of clinical investigation","url":"https://pubmed.ncbi.nlm.nih.gov/12438449","citation_count":175,"is_preprint":false},{"pmid":"10601355","id":"PMC_10601355","title":"Recognition of the class Ib molecule Qa-1(b) by putative activating receptors CD94/NKG2C and CD94/NKG2E on mouse natural killer cells.","date":"1999","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/10601355","citation_count":167,"is_preprint":false},{"pmid":"15528343","id":"PMC_15528343","title":"Negative regulation of NK cell activities by inhibitory receptor CD94/NKG2A leads to altered NK cell-induced modulation of dendritic cell functions in chronic hepatitis C virus infection.","date":"2004","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/15528343","citation_count":164,"is_preprint":false},{"pmid":"9933082","id":"PMC_9933082","title":"Transforming growth factor-beta-induced expression of CD94/NKG2A inhibitory receptors in human T lymphocytes.","date":"1999","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/9933082","citation_count":163,"is_preprint":false},{"pmid":"11812997","id":"PMC_11812997","title":"CD94-NKG2A receptors regulate antiviral CD8(+) T cell responses.","date":"2002","source":"Nature immunology","url":"https://pubmed.ncbi.nlm.nih.gov/11812997","citation_count":160,"is_preprint":false},{"pmid":"12675520","id":"PMC_12675520","title":"Interaction of heat shock protein 70 peptide with NK cells involves the NK receptor CD94.","date":"2003","source":"Biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12675520","citation_count":151,"is_preprint":false},{"pmid":"22384114","id":"PMC_22384114","title":"Cytotoxicity of CD56(bright) NK cells towards autologous activated CD4+ T cells is mediated through NKG2D, LFA-1 and TRAIL and dampened via CD94/NKG2A.","date":"2012","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/22384114","citation_count":148,"is_preprint":false},{"pmid":"9209487","id":"PMC_9209487","title":"Interleukin-15-induced maturation of human natural killer cells from early thymic precursors: selective expression of CD94/NKG2-A as the only HLA class I-specific inhibitory receptor.","date":"1997","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/9209487","citation_count":138,"is_preprint":false},{"pmid":"8898964","id":"PMC_8898964","title":"CD94 functions as a natural killer cell inhibitory receptor for different HLA class I alleles: identification of the inhibitory form of CD94 by the use of novel monoclonal antibodies.","date":"1996","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/8898964","citation_count":133,"is_preprint":false},{"pmid":"9550399","id":"PMC_9550399","title":"CD94/NKG2 inhibitory receptor complex modulates both anti-viral and anti-tumoral responses of polyclonal phosphoantigen-reactive V gamma 9V delta 2 T lymphocytes.","date":"1997","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/9550399","citation_count":129,"is_preprint":false},{"pmid":"9059892","id":"PMC_9059892","title":"Structure and function of the CD94 C-type lectin receptor complex involved in recognition of HLA class I molecules.","date":"1997","source":"Immunological reviews","url":"https://pubmed.ncbi.nlm.nih.gov/9059892","citation_count":120,"is_preprint":false},{"pmid":"17172651","id":"PMC_17172651","title":"The CD94/NKG2 family of receptors: from molecules and cells to clinical relevance.","date":"2006","source":"Immunologic research","url":"https://pubmed.ncbi.nlm.nih.gov/17172651","citation_count":119,"is_preprint":false},{"pmid":"27853650","id":"PMC_27853650","title":"Therapeutic CD94/NKG2A blockade improves natural killer cell dysfunction in chronic lymphocytic leukemia.","date":"2016","source":"Oncoimmunology","url":"https://pubmed.ncbi.nlm.nih.gov/27853650","citation_count":116,"is_preprint":false},{"pmid":"10023772","id":"PMC_10023772","title":"Structure of CD94 reveals a novel C-type lectin fold: implications for the NK cell-associated CD94/NKG2 receptors.","date":"1999","source":"Immunity","url":"https://pubmed.ncbi.nlm.nih.gov/10023772","citation_count":111,"is_preprint":false},{"pmid":"10328195","id":"PMC_10328195","title":"Response of murine and normal human skin to injection of allogeneic blood-derived psoriatic immunocytes: detection of T cells expressing receptors typically present on natural killer cells, including CD94, CD158, and CD161.","date":"1999","source":"Archives of dermatology","url":"https://pubmed.ncbi.nlm.nih.gov/10328195","citation_count":110,"is_preprint":false},{"pmid":"9190923","id":"PMC_9190923","title":"The CD94/NKG2-A inhibitory receptor complex is involved in natural killer cell-mediated recognition of cells expressing HLA-G1.","date":"1997","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/9190923","citation_count":109,"is_preprint":false},{"pmid":"12387742","id":"PMC_12387742","title":"TCR specificity dictates CD94/NKG2A expression by human CTL.","date":"2002","source":"Immunity","url":"https://pubmed.ncbi.nlm.nih.gov/12387742","citation_count":108,"is_preprint":false},{"pmid":"9565368","id":"PMC_9565368","title":"Specific engagement of the CD94/NKG2-A killer inhibitory receptor by the HLA-E class Ib molecule induces SHP-1 phosphatase recruitment to tyrosine-phosphorylated NKG2-A: evidence for receptor function in heterologous transfectants.","date":"1998","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/9565368","citation_count":101,"is_preprint":false},{"pmid":"9600963","id":"PMC_9600963","title":"Murine Nkg2d and Cd94 are clustered within the natural killer complex and are expressed independently in natural killer cells.","date":"1998","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/9600963","citation_count":100,"is_preprint":false},{"pmid":"11238637","id":"PMC_11238637","title":"The repertoire of killer cell Ig-like receptor and CD94:NKG2A receptors in T cells: clones sharing identical alpha beta TCR rearrangement express highly diverse killer cell Ig-like receptor patterns.","date":"2001","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/11238637","citation_count":100,"is_preprint":false},{"pmid":"15258309","id":"PMC_15258309","title":"The role of CD94/NKG2 in innate and adaptive immunity.","date":"2004","source":"Immunologic research","url":"https://pubmed.ncbi.nlm.nih.gov/15258309","citation_count":98,"is_preprint":false},{"pmid":"24666761","id":"PMC_24666761","title":"The CD94/NKG2C+ NK-cell subset on the edge of innate and adaptive immunity to human cytomegalovirus infection.","date":"2014","source":"Seminars in immunology","url":"https://pubmed.ncbi.nlm.nih.gov/24666761","citation_count":94,"is_preprint":false},{"pmid":"9485212","id":"PMC_9485212","title":"The activating form of CD94 receptor complex: CD94 covalently associates with the Kp39 protein that represents the product of the NKG2-C gene.","date":"1998","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/9485212","citation_count":93,"is_preprint":false},{"pmid":"21439856","id":"PMC_21439856","title":"CD94 is essential for NK cell-mediated resistance to a lethal viral disease.","date":"2011","source":"Immunity","url":"https://pubmed.ncbi.nlm.nih.gov/21439856","citation_count":93,"is_preprint":false},{"pmid":"15115287","id":"PMC_15115287","title":"Heat shock protein 70-reactivity is associated with increased cell surface density of CD94/CD56 on primary natural killer cells.","date":"2003","source":"Cell stress & chaperones","url":"https://pubmed.ncbi.nlm.nih.gov/15115287","citation_count":88,"is_preprint":false},{"pmid":"18339401","id":"PMC_18339401","title":"Subtle changes in peptide conformation profoundly affect recognition of the non-classical MHC class I molecule HLA-E by the CD94-NKG2 natural killer cell receptors.","date":"2008","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/18339401","citation_count":88,"is_preprint":false},{"pmid":"39121847","id":"PMC_39121847","title":"LAG-3 sustains TOX expression and regulates the CD94/NKG2-Qa-1b axis to govern exhausted CD8 T cell NK receptor expression and cytotoxicity.","date":"2024","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/39121847","citation_count":86,"is_preprint":false},{"pmid":"16951318","id":"PMC_16951318","title":"CD94/NKG2A inhibits NK cell activation by disrupting the actin network at the immunological synapse.","date":"2006","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/16951318","citation_count":85,"is_preprint":false},{"pmid":"18083576","id":"PMC_18083576","title":"The heterodimeric assembly of the CD94-NKG2 receptor family and implications for human leukocyte antigen-E recognition.","date":"2007","source":"Immunity","url":"https://pubmed.ncbi.nlm.nih.gov/18083576","citation_count":82,"is_preprint":false},{"pmid":"21800130","id":"PMC_21800130","title":"Clinical significance of the HLA-E and CD94/NKG2 interaction.","date":"2011","source":"Archivum immunologiae et therapiae experimentalis","url":"https://pubmed.ncbi.nlm.nih.gov/21800130","citation_count":81,"is_preprint":false},{"pmid":"9295021","id":"PMC_9295021","title":"HLA-G recognition by human natural killer cells. Involvement of CD94 both as inhibitory and as activating receptor complex.","date":"1997","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/9295021","citation_count":81,"is_preprint":false},{"pmid":"31213473","id":"PMC_31213473","title":"Enriched HLA-E and CD94/NKG2A Interaction Limits Antitumor CD8+ Tumor-Infiltrating T Lymphocyte Responses.","date":"2019","source":"Cancer immunology research","url":"https://pubmed.ncbi.nlm.nih.gov/31213473","citation_count":80,"is_preprint":false},{"pmid":"14971033","id":"PMC_14971033","title":"The inhibitory NK cell receptor CD94/NKG2A and the activating receptor CD94/NKG2C bind the top of HLA-E through mostly shared but partly distinct sets of HLA-E residues.","date":"2004","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/14971033","citation_count":79,"is_preprint":false},{"pmid":"17976318","id":"PMC_17976318","title":"High expression of NKG2A/CD94 and low expression of granzyme B are associated with reduced cord blood NK cell activity.","date":"2007","source":"Cellular & molecular immunology","url":"https://pubmed.ncbi.nlm.nih.gov/17976318","citation_count":77,"is_preprint":false},{"pmid":"24030638","id":"PMC_24030638","title":"NKG2C zygosity influences CD94/NKG2C receptor function and the NK-cell compartment redistribution in response to human cytomegalovirus.","date":"2013","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/24030638","citation_count":76,"is_preprint":false},{"pmid":"33887202","id":"PMC_33887202","title":"The CD94/NKG2A inhibitory receptor educates uterine NK cells to optimize pregnancy outcomes in humans and mice.","date":"2021","source":"Immunity","url":"https://pubmed.ncbi.nlm.nih.gov/33887202","citation_count":74,"is_preprint":false},{"pmid":"15940674","id":"PMC_15940674","title":"The CD94/NKG2C killer lectin-like receptor constitutes an alternative activation pathway for a subset of CD8+ T cells.","date":"2005","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/15940674","citation_count":74,"is_preprint":false},{"pmid":"12480700","id":"PMC_12480700","title":"Monoclonal T-cell expansions in asymptomatic individuals and in patients with large granular leukemia consist of cytotoxic effector T cells expressing the activating CD94:NKG2C/E and NKD2D killer cell receptors.","date":"2002","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/12480700","citation_count":73,"is_preprint":false},{"pmid":"15607803","id":"PMC_15607803","title":"The cell biology of the human natural killer cell CD94/NKG2A inhibitory receptor.","date":"2005","source":"Molecular immunology","url":"https://pubmed.ncbi.nlm.nih.gov/15607803","citation_count":71,"is_preprint":false},{"pmid":"11751968","id":"PMC_11751968","title":"Conservation and variation in human and common chimpanzee CD94 and NKG2 genes.","date":"2002","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/11751968","citation_count":71,"is_preprint":false},{"pmid":"11782535","id":"PMC_11782535","title":"Implications of CD94 deficiency and monoallelic NKG2A expression for natural killer cell development and repertoire formation.","date":"2002","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/11782535","citation_count":67,"is_preprint":false},{"pmid":"31409873","id":"PMC_31409873","title":"The inhibitory receptor CD94/NKG2A on CD8+ tumor-infiltrating lymphocytes in colorectal cancer: a promising new druggable immune checkpoint in the context of HLAE/β2m overexpression.","date":"2019","source":"Modern pathology : an official journal of the United States and Canadian Academy of Pathology, Inc","url":"https://pubmed.ncbi.nlm.nih.gov/31409873","citation_count":66,"is_preprint":false},{"pmid":"19124726","id":"PMC_19124726","title":"IL-12-dependent inducible expression of the CD94/NKG2A inhibitory receptor regulates CD94/NKG2C+ NK cell function.","date":"2009","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/19124726","citation_count":65,"is_preprint":false},{"pmid":"21989990","id":"PMC_21989990","title":"Soluble HLA-G dampens CD94/NKG2A expression and function and differentially modulates chemotaxis and cytokine and chemokine secretion in CD56bright and CD56dim NK cells.","date":"2011","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/21989990","citation_count":63,"is_preprint":false},{"pmid":"10229073","id":"PMC_10229073","title":"Differential regulation of killer cell Ig-like receptors and CD94 lectin-like dimers on NK and T lymphocytes from HIV-1-infected individuals.","date":"1999","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/10229073","citation_count":62,"is_preprint":false},{"pmid":"29898768","id":"PMC_29898768","title":"KLRD1-expressing natural killer cells predict influenza susceptibility.","date":"2018","source":"Genome medicine","url":"https://pubmed.ncbi.nlm.nih.gov/29898768","citation_count":61,"is_preprint":false},{"pmid":"10671222","id":"PMC_10671222","title":"CD69-triggered ERK activation and functions are negatively regulated by CD94 / NKG2-A inhibitory receptor.","date":"2000","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/10671222","citation_count":59,"is_preprint":false},{"pmid":"10358137","id":"PMC_10358137","title":"Cutting edge: expression of functional CD94/NKG2A inhibitory receptors on fetal NK1.1+Ly-49- cells: a possible mechanism of tolerance during NK cell development.","date":"1999","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/10358137","citation_count":58,"is_preprint":false},{"pmid":"37264229","id":"PMC_37264229","title":"HLA class I signal peptide polymorphism determines the level of CD94/NKG2-HLA-E-mediated regulation of effector cell responses.","date":"2023","source":"Nature immunology","url":"https://pubmed.ncbi.nlm.nih.gov/37264229","citation_count":57,"is_preprint":false},{"pmid":"11994435","id":"PMC_11994435","title":"Expression of CD94/NKG2-A on human T lymphocytes is induced by IL-12: implications for adoptive immunotherapy.","date":"2002","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/11994435","citation_count":57,"is_preprint":false},{"pmid":"12697440","id":"PMC_12697440","title":"Expression of CD94-NKG2A inhibitory receptor is restricted to a subset of CD8+ T cells.","date":"2003","source":"Trends in immunology","url":"https://pubmed.ncbi.nlm.nih.gov/12697440","citation_count":55,"is_preprint":false},{"pmid":"16488482","id":"PMC_16488482","title":"Expression patterns of lectin-like natural killer receptors, inhibitory CD94/NKG2A, and activating CD94/NKG2C on decidual CD56bright natural killer cells differ from those on peripheral CD56dim natural killer cells.","date":"2006","source":"Journal of reproductive immunology","url":"https://pubmed.ncbi.nlm.nih.gov/16488482","citation_count":55,"is_preprint":false},{"pmid":"9469418","id":"PMC_9469418","title":"Participation of the CD94 receptor complex in costimulation of human natural killer cells.","date":"1998","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/9469418","citation_count":55,"is_preprint":false},{"pmid":"15517612","id":"PMC_15517612","title":"Activating CD94:NKG2C and inhibitory CD94:NKG2A receptors are expressed by distinct subsets of committed CD8+ TCR alphabeta lymphocytes.","date":"2004","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/15517612","citation_count":54,"is_preprint":false},{"pmid":"20132973","id":"PMC_20132973","title":"CD94/NKG2C is a killer effector molecule in patients with Stevens-Johnson syndrome and toxic epidermal necrolysis.","date":"2010","source":"The Journal of allergy and clinical immunology","url":"https://pubmed.ncbi.nlm.nih.gov/20132973","citation_count":51,"is_preprint":false},{"pmid":"10570324","id":"PMC_10570324","title":"HLA-E and HLA-G expression on porcine endothelial cells inhibit xenoreactive human NK cells through CD94/NKG2-dependent and -independent pathways.","date":"1999","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/10570324","citation_count":51,"is_preprint":false},{"pmid":"8816383","id":"PMC_8816383","title":"Clonotypic differences in signaling from CD94 (kp43) on NK cells lead to divergent cellular responses.","date":"1996","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/8816383","citation_count":50,"is_preprint":false},{"pmid":"11254682","id":"PMC_11254682","title":"Expression of Ly49E and CD94/NKG2 on fetal and adult NK cells.","date":"2001","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/11254682","citation_count":47,"is_preprint":false},{"pmid":"11907085","id":"PMC_11907085","title":"Expression of inhibitory receptors Ly49E and CD94/NKG2 on fetal thymic and adult epidermal TCR V gamma 3 lymphocytes.","date":"2002","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/11907085","citation_count":47,"is_preprint":false},{"pmid":"15746081","id":"PMC_15746081","title":"IFN-gamma-mediated negative feedback regulation of NKT-cell function by CD94/NKG2.","date":"2005","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/15746081","citation_count":46,"is_preprint":false},{"pmid":"11782245","id":"PMC_11782245","title":"The KIR and CD94/NKG2 families of molecules in the rhesus monkey.","date":"2001","source":"Immunological reviews","url":"https://pubmed.ncbi.nlm.nih.gov/11782245","citation_count":44,"is_preprint":false},{"pmid":"11513155","id":"PMC_11513155","title":"Ly49 and CD94/NKG2: developmentally regulated expression and evolution.","date":"2001","source":"Immunological reviews","url":"https://pubmed.ncbi.nlm.nih.gov/11513155","citation_count":42,"is_preprint":false},{"pmid":"8955184","id":"PMC_8955184","title":"Biochemical and serologic evidence for the existence of functionally distinct forms of the CD94 NK cell receptor.","date":"1996","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/8955184","citation_count":42,"is_preprint":false},{"pmid":"21151939","id":"PMC_21151939","title":"Development and function of CD94-deficient natural killer cells.","date":"2010","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/21151939","citation_count":41,"is_preprint":false},{"pmid":"10828054","id":"PMC_10828054","title":"Expression of CD94/NKG2A and killer immunoglobulin-like receptors in NK cells and a subset of extranodal cytotoxic T-cell lymphomas.","date":"2000","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/10828054","citation_count":41,"is_preprint":false},{"pmid":"32553157","id":"PMC_32553157","title":"High CD26 and Low CD94 Expression Identifies an IL-23 Responsive Vδ2+ T Cell Subset with a MAIT Cell-like Transcriptional Profile.","date":"2020","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/32553157","citation_count":39,"is_preprint":false},{"pmid":"17706207","id":"PMC_17706207","title":"Increased frequency of human leukocyte antigen-E inhibitory receptor CD94/NKG2A-expressing peritoneal natural killer cells in patients with endometriosis.","date":"2007","source":"Fertility and sterility","url":"https://pubmed.ncbi.nlm.nih.gov/17706207","citation_count":39,"is_preprint":false},{"pmid":"21890659","id":"PMC_21890659","title":"Selenite induces posttranscriptional blockade of HLA-E expression and sensitizes tumor cells to CD94/NKG2A-positive NK cells.","date":"2011","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/21890659","citation_count":38,"is_preprint":false},{"pmid":"10358164","id":"PMC_10358164","title":"CD94/NKG2-A inhibitory complex blocks CD16-triggered Syk and extracellular regulated kinase activation, leading to cytotoxic function of human NK cells.","date":"1999","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/10358164","citation_count":37,"is_preprint":false},{"pmid":"9842883","id":"PMC_9842883","title":"Phosphoantigen activation induces surface translocation of intracellular CD94/NKG2A class I receptor on CD94- peripheral Vgamma9 Vdelta2 T cells but not on CD94- thymic or mature gammadelta T cell clones.","date":"1998","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/9842883","citation_count":36,"is_preprint":false},{"pmid":"16609008","id":"PMC_16609008","title":"Coengagement of CD16 and CD94 receptors mediates secretion of chemokines and induces apoptotic death of naive natural killer cells.","date":"2006","source":"Clinical cancer research : an official journal of the American Association for Cancer Research","url":"https://pubmed.ncbi.nlm.nih.gov/16609008","citation_count":36,"is_preprint":false},{"pmid":"15978547","id":"PMC_15978547","title":"Prostaglandin E2 induces the expression of functional inhibitory CD94/NKG2A receptors in human CD8+ T lymphocytes by a cAMP-dependent protein kinase A type I pathway.","date":"2005","source":"Biochemical pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/15978547","citation_count":36,"is_preprint":false},{"pmid":"24673109","id":"PMC_24673109","title":"Balance between activating NKG2D, DNAM-1, NKp44 and NKp46 and inhibitory CD94/NKG2A receptors determine natural killer degranulation towards rheumatoid arthritis synovial fibroblasts.","date":"2014","source":"Immunology","url":"https://pubmed.ncbi.nlm.nih.gov/24673109","citation_count":36,"is_preprint":false},{"pmid":"12444112","id":"PMC_12444112","title":"NK cell CD94/NKG2A inhibitory receptors are internalized and recycle independently of inhibitory signaling processes.","date":"2002","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/12444112","citation_count":34,"is_preprint":false},{"pmid":"32575403","id":"PMC_32575403","title":"NKG2A/CD94 Is a New Immune Receptor for HLA-G and Distinguishes Amino Acid Differences in the HLA-G Heavy Chain.","date":"2020","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/32575403","citation_count":33,"is_preprint":false},{"pmid":"9472066","id":"PMC_9472066","title":"Structure of the human CD94 C-type lectin gene.","date":"1998","source":"Immunogenetics","url":"https://pubmed.ncbi.nlm.nih.gov/9472066","citation_count":33,"is_preprint":false},{"pmid":"17531784","id":"PMC_17531784","title":"Reconstitution of natural killer cell receptor repertoires after unmanipulated HLA-mismatched/haploidentical blood and marrow transplantation: analyses of CD94:NKG2A and killer immunoglobulin-like receptor expression and their associations with clinical outcome.","date":"2007","source":"Biology of blood and marrow transplantation : journal of the American Society for Blood and Marrow Transplantation","url":"https://pubmed.ncbi.nlm.nih.gov/17531784","citation_count":33,"is_preprint":false},{"pmid":"15714583","id":"PMC_15714583","title":"The role of TCR stimulation and TGF-beta in controlling the expression of CD94/NKG2A receptors on CD8 T cells.","date":"2005","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/15714583","citation_count":33,"is_preprint":false},{"pmid":"11994449","id":"PMC_11994449","title":"Orderly and nonstochastic acquisition of CD94/NKG2 receptors by developing NK cells derived from embryonic stem cells in vitro.","date":"2002","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/11994449","citation_count":33,"is_preprint":false},{"pmid":"12097371","id":"PMC_12097371","title":"CD94/NKG2 expression does not inhibit cytotoxic function of lymphocytic choriomeningitis virus-specific CD8+ T cells.","date":"2002","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/12097371","citation_count":33,"is_preprint":false},{"pmid":"34615883","id":"PMC_34615883","title":"CD127+ CD94+ innate lymphoid cells expressing granulysin and perforin are expanded in patients with Crohn's disease.","date":"2021","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/34615883","citation_count":32,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":49850,"output_tokens":9429,"usd":0.145492,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":19505,"output_tokens":5334,"usd":0.115437,"stage2_stop_reason":"end_turn"},"total_usd":0.260929,"stage1_batch_id":"msgbatch_01BbTCMyrRPyhtEq6b1MdwCN","stage2_batch_id":"msgbatch_011dEed5bbxYvTAaQWKJevxu","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1996,\n      \"finding\": \"CD94 glycoproteins form disulfide-bonded heterodimers with NKG2A/B, NKG2C, and NKG2E glycoproteins. NKG2A/B possesses two ITIM sequences in its cytoplasmic domain responsible for inhibitory function, whereas other NKG2 proteins lack ITIMs and may transmit positive signals.\",\n      \"method\": \"Biochemical co-immunoprecipitation, SDS-PAGE, sequence analysis of cytoplasmic domains\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — reciprocal biochemical characterization replicated across multiple labs; foundational structural/biochemical finding confirmed by subsequent studies\",\n      \"pmids\": [\"8943374\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"CD94 exists in at least two biochemically and serologically distinct forms: an inhibitory form (~43 kDa, group B clones) and a stimulatory form (~39 kDa, group A clones). The inhibitory form is selectively recognized by the Z199 mAb. CD94 is assembled as a disulfide-linked dimer.\",\n      \"method\": \"Immunoprecipitation, SDS-PAGE, N-glycanase and V8 protease digestion, reverse ADCC functional assays\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — multiple orthogonal biochemical methods in single study, confirmed by subsequent structural studies\",\n      \"pmids\": [\"8955184\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"The inhibitory NK cell receptor is a covalent heterodimer of CD94 and NKG2-A (~43 kDa). NKG2-B, an alternatively spliced product of NKG2-A, also assembles with CD94. Both NKG2-A and NKG2-B contain cytoplasmic ITIMs providing the molecular basis for inhibitory function.\",\n      \"method\": \"Co-immunoprecipitation with anti-CD94 mAb, SDS-PAGE, identification of NKG2-A protein, ITIM sequence analysis\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — co-IP with biochemical characterization, independently confirmed by multiple labs\",\n      \"pmids\": [\"9045931\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"NKG2A (~43 kDa) is covalently associated with CD94 on the surface of NK cells. Cell surface expression of NKG2A requires association with CD94 (as glycosylation patterns characteristic of mature proteins are found only in NKG2A associated with CD94). NKG2A contains two ITIMs consistent with its inhibitory function.\",\n      \"method\": \"Co-immunoprecipitation, glycosylation analysis, NK clone functional analysis\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — biochemical co-IP with glycosylation maturation evidence; replicated independently\",\n      \"pmids\": [\"9034158\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"CD94 ligation on group A (activating) NK clones induces activation of intracellular PTKs (lck and ZAP-70), phospholipase C, and PI3-kinase. In contrast, CD94 ligation on group B (inhibitory) clones inhibits FcR-induced tyrosine phosphorylations of ZAP-70 and PLC-γ2, formation of phospho-zeta/ZAP-70 complexes, and release of inositol phosphates.\",\n      \"method\": \"Biochemical signaling assays, kinase activation assays, phosphorylation studies on sorted NK clones\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — multiple orthogonal signaling assays in single lab defining divergent signaling pathways\",\n      \"pmids\": [\"8816383\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"HLA-E tetramers bind specifically to CD94/NKG2A, CD94/NKG2B, and CD94/NKG2C NK cell receptor complexes on transfectants, but not to immunoglobulin-family KIR receptors. Surface expression of HLA-E is sufficient to protect target cells from lysis by CD94/NKG2A+ NK-cell clones.\",\n      \"method\": \"HLA-E tetramer binding to transfectants, NK cytotoxicity assays with antibody blocking\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — tetramer binding with functional validation, replicated independently by multiple labs\",\n      \"pmids\": [\"9486650\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"HLA-E is a major ligand for the CD94/NKG2A inhibitory receptor complex. Stabilization of HLA-E surface expression by appropriate HLA class I leader sequence peptides is sufficient to confer protection from NK lysis via CD94/NKG2A recognition. The inhibitory interaction is not mediated through Ig-SF KIRs or ILT2/LIR1.\",\n      \"method\": \"NK cytotoxicity assays, antibody blocking with anti-HLA-E, anti-CD94, anti-CD94/NKG2A mAbs; cold-target loading with leader peptides\",\n      \"journal\": \"Proceedings of the National Academy of Sciences\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — functional reconstitution with blocking antibodies, replicated by multiple labs\",\n      \"pmids\": [\"9560253\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"CD94/NKG2C (activating receptor) noncovalently associates with DAP12, a membrane receptor containing an ITAM. Efficient surface expression of CD94/NKG2C requires DAP12. Charged residues in the transmembrane domains of DAP12 and NKG2C are necessary for this interaction.\",\n      \"method\": \"Co-immunoprecipitation, transfection with wild-type and mutant constructs, surface expression analysis\",\n      \"journal\": \"Immunity\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — co-IP with transmembrane domain mutagenesis demonstrating requirement for charged residues\",\n      \"pmids\": [\"9655483\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"Specific engagement of CD94/NKG2-A by HLA-E induces tyrosine phosphorylation of the NKG2-A subunit and SHP-1 recruitment. These early biochemical events were also detected upon NK cell interaction with HLA-E+ transfectants and were prevented by anti-HLA class I mAb. In RBL-2H3 transfectants, CD94/NKG2-A cross-linking promoted NKG2-A tyrosine phosphorylation, SHP-1 co-precipitation, and inhibition of Fc-εRI-triggered secretion.\",\n      \"method\": \"Tyrosine phosphorylation assays, SHP-1 co-immunoprecipitation, RBL-2H3 transfection reconstitution, cytotoxicity assays\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — reconstitution in heterologous cell system plus primary NK cell data, multiple orthogonal methods\",\n      \"pmids\": [\"9565368\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"Mouse NKG2A forms a CD94/NKG2A heterodimer that directly recognizes the nonclassical MHC class Ib molecule Qa-1(b) in a peptide (Qdm)-dependent manner, leading to inhibition of NK-mediated target cell lysis.\",\n      \"method\": \"Qa-1(b) tetramer binding, cloning of mouse NKG2A, NK cytotoxicity assays with peptide loading\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — direct tetramer binding assay with functional validation; mouse ortholog study\",\n      \"pmids\": [\"9815261\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"The activating CD94/NKG2C receptor complex is formed by covalent association of CD94 with NKG2-C (Kp39). COS7 cotransfection of CD94 and NKG2-C confirmed the identity of Kp39 as NKG2-C. The P25 mAb triggered cytolytic activity via this complex in redirected killing.\",\n      \"method\": \"Co-immunoprecipitation, COS7 co-transfection, peptide mapping, RT-PCR on NK clones, redirected killing assay\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — reconstitution by co-transfection confirmed biochemical identity; multiple orthogonal methods\",\n      \"pmids\": [\"9485212\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"The inhibitory CD94/NKG2-A receptor has a higher binding affinity for HLA-E than the activating CD94/NKG2-C receptor. Both receptors show very fast association and dissociation kinetics. Recognition of HLA-E by both receptors is peptide-dependent, and binding affinity of peptide-HLA-E complexes directly correlates with triggering of NK cell responses.\",\n      \"method\": \"Surface plasmon resonance (BIAcore) with soluble recombinant HLA-E and soluble CD94/NKG2-A and CD94/NKG2-C proteins; NK functional assays\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro binding kinetics with purified recombinant proteins correlated with functional assays in single lab\",\n      \"pmids\": [\"10428963\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"The crystal structure of the CD94 extracellular domain reveals a unique C-type lectin fold variation in which the second alpha-helix is replaced by a loop, the putative carbohydrate-binding site is altered, and the Ca2+-binding site appears nonfunctional. The CD94 dimer observed in the crystal has an extensive hydrophobic interface and reveals a putative ligand-binding region for HLA-E, suggesting how NKG2 interacts with CD94.\",\n      \"method\": \"X-ray crystallography at 2.6 Å resolution\",\n      \"journal\": \"Immunity\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure at 2.6 Å; single study but high-quality structural method\",\n      \"pmids\": [\"10023772\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"CD94/NKG2-A inhibitory complex blocks CD16-triggered Syk kinase activation and tyrosine phosphorylation of the CD16 zeta subunit. It also inhibits ERK activation by blocking Shc tyrosine phosphorylation and Shc/Grb-2 complex formation downstream of CD16.\",\n      \"method\": \"Kinase activity assays, co-immunoprecipitation, western blotting for phosphorylation, ERK activation assays\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — multiple orthogonal signaling assays defining inhibitory signaling pathway\",\n      \"pmids\": [\"10358164\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Mouse CD94/NKG2C and CD94/NKG2E also bind to Qa-1(b), and these are activating receptors based on cytoplasmic domain features. An anti-NKG2 blocking mAb demonstrated that CD94/NKG2 molecules are the only Qa-1(b) receptors on NK cells.\",\n      \"method\": \"Cloning and expression, Qa-1(b) binding assays, anti-NKG2 blocking mAb, RT-PCR\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — receptor cloning with direct Qa-1(b) binding demonstrated and blocking mAb validation\",\n      \"pmids\": [\"10601355\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"HLA-E is expressed on the surface of trophoblast cells and the majority of decidual NK cells bind HLA-E tetramers; this binding is inhibited by anti-CD94 mAb. The overall functional consequence of CD94/NKG2 interaction with HLA-E on decidual NK cells is inhibition of cytotoxicity.\",\n      \"method\": \"HLA-E tetramer binding, flow cytometry, anti-CD94 blocking, cytotoxicity assays with decidual NK cells\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — tetramer binding with anti-CD94 blocking and functional cytotoxicity assays\",\n      \"pmids\": [\"10898498\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"CD94/NKG2A receptors continuously recycle between the cell surface and intracellular endosomal compartments in an active process requiring energy and the cytoskeleton. CD94/NKG2A uses a distinct recycling compartment from transferrin receptor. CD94/NKG2A internalization is independent of ligand cross-linking or functional ITIM motifs.\",\n      \"method\": \"Flow cytometry, confocal microscopy, biochemical fractionation, transfection of wild-type and ITIM-mutant CD94/NKG2A in RBL-2H3 cells\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (flow, confocal, biochemistry) with mutagenesis in reconstituted system\",\n      \"pmids\": [\"12444112\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"CD94/NKG2A engagement prevents NK cell activation by disrupting the actin network and excluding lipid rafts at the inhibitory NK immunological synapse (iNKIS). This involves SHP-1 recruitment and activation, leading to dephosphorylation of Vav1 and ezrin-radixin-moesin (ERM) proteins. Actin polymerization inhibition abolished lipid raft exclusion at iNKIS, whereas cholesterol depletion did not affect actin disruption.\",\n      \"method\": \"Confocal microscopy, fluorescence imaging of immunological synapse, phosphorylation assays (Vav1, ERM), pharmacological inhibition of actin polymerization and cholesterol depletion\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (imaging + biochemistry + pharmacology) defining mechanism at immunological synapse\",\n      \"pmids\": [\"16951318\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Crystal structure of CD94-NKG2A heterodimer at 2.5 Å resolution reveals an asymmetric dimer interface despite structural homology between the two subunits, providing structural basis for preferred heterodimeric assembly. Extensive mutagenesis studies on HLA-E and CD94-NKG2A establish that the invariant CD94 chain plays a dominant role in interacting with HLA-E compared to the variable NKG2 chain.\",\n      \"method\": \"X-ray crystallography at 2.5 Å, site-directed mutagenesis of HLA-E and CD94-NKG2A interface residues\",\n      \"journal\": \"Immunity\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure with extensive mutagenesis validation; independently confirmed by two contemporaneous structural studies\",\n      \"pmids\": [\"18083576\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Crystal structure of CD94-NKG2A in complex with HLA-E (bound to HLA-G leader peptide) shows that the CD94 subunit dominates the interaction with HLA-E, while NKG2A is more peripheral to the interface. CD94 dominates peptide-mediated contacts with poor surface and chemical complementarity. The interaction shows little conformational change upon ligation ('lock and key' mode). Mutagenesis data confirmed the CD94-NKG2A-HLA-E interface.\",\n      \"method\": \"X-ray crystallography of ternary complex, mutagenesis at CD94-NKG2A-HLA-E interface\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure of ternary complex with mutagenesis validation; independently confirmed by contemporaneous structural study\",\n      \"pmids\": [\"18332182\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Crystal structure of NKG2A/CD94/HLA-E at 4.4 Å resolution reveals that the C-terminal region of the bound peptide interacts entirely with CD94 (the invariant component). Residues 167-170 of NKG2A/C (at the CD94 heterodimer interface, not contacting HLA-E directly) account for the ~6-fold higher affinity of inhibitory NKG2A/CD94 compared to activating NKG2C/CD94 for HLA-E.\",\n      \"method\": \"X-ray crystallography at 4.4 Å, comparative analysis with NKG2C structure, evolutionary analysis\",\n      \"journal\": \"Proceedings of the National Academy of Sciences\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure with mechanistic insight; consistent with contemporaneous structural work\",\n      \"pmids\": [\"18448674\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Subtle changes in peptide conformation (without changes in HLA-E heavy chain conformation) profoundly affect CD94-NKG2 receptor recognition of HLA-E. Structures of HLA-E with HLA-Cw*07 leader peptide (low affinity) versus HLA-G*01 leader peptide (high affinity) at 2.5 Å show allotypic variations produce subtle differences in peptide conformation within the binding groove.\",\n      \"method\": \"X-ray crystallography of two HLA-E/peptide complexes at 2.5 Å resolution, compared with CD94-NKG2 binding data\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structures at 2.5 Å with direct binding comparison; single lab\",\n      \"pmids\": [\"18339401\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Both CD94/NKG2A (inhibitory) and CD94/NKG2C (activating) bind the top of HLA-E alpha1/alpha2 domain using mostly shared but partly distinct sets of HLA-E residues. Two HLA-E mutations (D69A and H155A) selectively abrogated binding to CD94/NKG2A but not to CD94/NKG2C, identifying differential contact residues.\",\n      \"method\": \"Alanine-scanning mutagenesis of HLA-E with binding assays to soluble CD94/NKG2A and CD94/NKG2C\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — systematic alanine scanning of the HLA-E surface with both inhibitory and activating receptor binding assays\",\n      \"pmids\": [\"14971033\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"CD69-triggered ERK activation and cell degranulation are negatively regulated by co-engagement of the CD94/NKG2-A inhibitory receptor. CD94/NKG2-A suppresses CD69-triggered degranulation by inhibiting ERK activation in RBL transfectants expressing both receptors.\",\n      \"method\": \"RBL-2H3 transfectants expressing CD69 and CD94/NKG2-A, ERK activation assays, degranulation assays, cytotoxicity assays\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — reconstituted system (RBL transfectants) with multiple signaling and functional readouts\",\n      \"pmids\": [\"10671222\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"HLA-E engagement of CD94/NKG2 complex on porcine endothelial cell transfectants leads to phosphorylation of the CD94/NKG2 complex and recruitment of SHP-1, mediating inhibition of xenoreactive human NK cells. In contrast, HLA-G inhibits NK cells through a CD94/NKG2-independent pathway without SHP-1 recruitment.\",\n      \"method\": \"Anti-CD94 blocking, SHP-1 co-immunoprecipitation, phosphorylation assays, xenogeneic cytotoxicity assays\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — SHP-1 co-IP and phosphorylation data with functional cytotoxicity assays; single lab\",\n      \"pmids\": [\"10570324\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Hsp70 protein and its C-terminal domain (Hsp70C) bind specifically to CD94 on NK cells (YT cell line). CD94-specific antibody completely abrogated Hsp70 binding. Competition assays with excess unlabeled Hsp70 (not unrelated GST) confirmed specific, concentration-dependent binding.\",\n      \"method\": \"Immunofluorescence binding studies, antibody blocking with anti-CD94 mAb, competition assays\",\n      \"journal\": \"Biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — binding assays on cell line with antibody blocking; single lab, no reconstitution or structural validation\",\n      \"pmids\": [\"12675520\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"CD94 is essential for resistance of C57BL/6 mice to ectromelia virus (mousepox). Ectromelia virus-infected cells expressing Qa-1(b) are specifically recognized by the activating receptor CD94-NKG2E, and CD94-deficient mice are highly susceptible to mousepox.\",\n      \"method\": \"CD94-deficient mouse infection model, NK cell depletion, genetic epistasis, survival/viral load assays\",\n      \"journal\": \"Immunity\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — gene-targeted KO mouse with defined viral susceptibility phenotype and receptor-ligand specificity established\",\n      \"pmids\": [\"21439856\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"CD94-deficient mice develop NK cells normally that efficiently kill NK-susceptible targets. Lack of CD94 receptors (and associated NKG2A, NKG2C, NKG2E) does not alter control of mouse CMV, LCMV, vaccinia virus, or Listeria monocytogenes, indicating CD94 is dispensable for NK cell development, education, and many innate immune functions.\",\n      \"method\": \"Gene-targeted CD94-deficient mouse, NK cell development and functional assays, viral and bacterial infection challenge models\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — gene-targeted KO with multiple defined negative phenotypic readouts; rigorous loss-of-function approach\",\n      \"pmids\": [\"21151939\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"CD94/NKG2C is coupled to DAP12 (KARAP) in CD8+ T cells, and specific engagement of CD94/NKG2C triggers cytotoxicity, cytokine production, IL-2Rα expression, and proliferative responses in CD94/NKG2C+ T cell clones. Anti-CD94 co-precipitation confirmed DAP12 association in T cells.\",\n      \"method\": \"Co-immunoprecipitation of DAP12 with anti-CD94, functional assays (cytotoxicity, cytokine production, proliferation) in T cell clones with selective receptor engagement\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP confirmed DAP12 association; multiple functional readouts in T cell clones; single lab\",\n      \"pmids\": [\"15940674\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Mouse Nkg2a is stochastically and monoallelically expressed, similar to Ly49 genes. DBA/2J mice are naturally CD94-deficient and do not express surface CD94/NKG2A receptors. CD94-deficient neonatal NK cells are self-tolerant, indicating self-tolerance of neonatal NK cells cannot be solely attributed to CD94/NKG2A expression.\",\n      \"method\": \"Allele-specific expression analysis, DBA/2J strain characterization, flow cytometry\",\n      \"journal\": \"Proceedings of the National Academy of Sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic analysis with flow cytometric validation; naturally occurring KO strain provides loss-of-function evidence\",\n      \"pmids\": [\"11782535\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"NKG2A genetic ablation in dams mated with wild-type males causes suboptimal maternal vascular responses in pregnancy, perturbed placental gene expression, reduced fetal weight, and abnormal fetal brain development. These results establish that the HLA-B→HLA-E→NKG2A pathway contributes to healthy pregnancy via NK cell education.\",\n      \"method\": \"NKG2A gene-targeted KO mouse crossed with wild-type males, vascular/placental/fetal phenotyping, genome-wide association study in humans for validation\",\n      \"journal\": \"Immunity\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — gene-targeted KO with defined pregnancy phenotypes plus human GWAS validation across multiple orthogonal approaches\",\n      \"pmids\": [\"33887202\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"CD94/NKG2A receptors move freely within the plasma membrane, accumulate at the site of contact with ligand-bearing target cells, and continuously recycle from the cell surface through endosomal compartments in a process requiring energy and the cytoskeleton. Lipid raft marker cholera toxin B is excluded from CD94/NKG2A-enriched contact sites; methylcyclodextrin does not interfere with CD94/NKG2A accumulation at contact sites.\",\n      \"method\": \"FRAP, live-cell fluorescence microscopy, pharmacological perturbations (cytoskeleton inhibitors, cholesterol depletion), confocal microscopy\",\n      \"journal\": \"Molecular immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — live imaging (FRAP), confocal, and pharmacological approaches establishing subcellular trafficking with functional context\",\n      \"pmids\": [\"15607803\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"CD94-NKG2A up-regulation on antiviral CD8+ T cells during acute polyoma virus infection is responsible for down-regulating their antigen-specific cytotoxicity during viral clearance and virus-induced oncogenesis.\",\n      \"method\": \"Murine polyoma virus infection model, flow cytometry of CD94/NKG2A expression on antigen-specific T cells, antibody blocking of CD94, cytotoxicity assays\",\n      \"journal\": \"Nature immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo mouse model with antibody blocking to establish causal role of CD94/NKG2A in CTL inhibition\",\n      \"pmids\": [\"11812997\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"IL-15 induces de novo expression of CD94 by T cells responding to superantigens; the simultaneous expression of NKG2A (forming functional CD94/NKG2A) is confined to CD8+ cells. Expression of CD94/NKG2A led to impairment of allo-specific cytolytic activity, which was restored by anti-CD94 mAb.\",\n      \"method\": \"In vitro T cell stimulation with superantigens in presence of IL-15, flow cytometry, cytotoxicity assays with anti-CD94 mAb blocking\",\n      \"journal\": \"Proceedings of the National Academy of Sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional induction system with antibody-blocking demonstration of causal role; single lab\",\n      \"pmids\": [\"9448304\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"TGF-β induces expression of CD94/NKG2A in T cells responding to bacterial superantigens. Expression preferentially occurs at low TGF-β concentrations, NKG2A expression is mostly confined to CD8+ cells, and mAb-mediated cross-linking of CD94/NKG2A impairs T cell triggering via CD3.\",\n      \"method\": \"In vitro stimulation of T cells with superantigens + TGF-β, flow cytometry, redirected killing assay\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional assays linking TGF-β induction to inhibitory receptor expression and function; single lab\",\n      \"pmids\": [\"9933082\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"LAG-3 sustains CD94/NKG2A expression on exhausted CD8 T cells by maintaining TOX expression. A LAG-3-dependent circuit generates a CD94/NKG2+ subset of exhausted T cells with enhanced cytotoxicity mediated by recognition of the stress ligand Qa-1b (and HLA-E in humans).\",\n      \"method\": \"LAG-3 genetic deletion during chronic LCMV infection, single-cell analysis, functional cytotoxicity assays, Qa-1b blocking, TOX expression analysis\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO with mechanistic epistasis (LAG-3→TOX→CD94/NKG2A→Qa-1b recognition), multiple orthogonal methods\",\n      \"pmids\": [\"39121847\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"NKG2A/CD94 was identified as a cognate receptor for HLA-G*01:01, with binding affinity dependent on the amino acid composition of the HLA-G heavy chain (HLA-G*01:04 shows highest affinity, while HLA-G*01:03 and HLA-G*01:01 show lower binding).\",\n      \"method\": \"Ligand-based receptor capture on living NK cells using sHLA-G*01:01 coupled to TriCEPS followed by mass spectrometry; reciprocal validation with recombinant soluble NKG2A/CD94 targeting HLA-G-expressing K562 cells\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — two orthogonal binding methods (TriCEPS capture + reciprocal recombinant protein binding); single lab\",\n      \"pmids\": [\"32575403\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Among 16 common classical HLA class I signal peptide variants, only 6 can be efficiently processed to generate epitopes that enable CD94/NKG2 engagement ('functional SPs'). The single functional HLA-B SP (HLA-B/-21M) confers the lowest receptor recognition by CD94/NKG2A/C despite inducing high HLA-E expression, because it competes with other SPs and reduces overall CD94/NKG2-HLA-E engagement.\",\n      \"method\": \"Systematic quantitative functional assays measuring HLA-E surface expression and CD94/NKG2A/C receptor engagement for all 16 common SP variants; competitive peptide loading assays\",\n      \"journal\": \"Nature immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — systematic quantitative approach across all common HLA-B SP variants with multiple orthogonal functional assays\",\n      \"pmids\": [\"37264229\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"The human CD94 gene contains six exons separated by five introns. The carbohydrate-recognition domain (CRD) is encoded by three exons. Transcription initiation is heterogeneous but restricted to a 60 bp region within a putative initiator element. CD94 is closely related to group V of C-type lectins based on intron position conservation within the CRD.\",\n      \"method\": \"Genomic cloning, exon-intron structure determination, primer extension, S1 nuclease protection assays\",\n      \"journal\": \"Immunogenetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct genomic characterization with transcription start site mapping; single lab\",\n      \"pmids\": [\"9472066\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"CD94 (KLRD1) functions as the invariant subunit of heterodimeric NK and T cell receptors by forming disulfide-bonded complexes with NKG2 family members (NKG2A/B forming inhibitory receptors via ITIM-mediated SHP-1 recruitment; NKG2C/E forming activating receptors via DAP12/ITAM association); the CD94 subunit dominates recognition of the non-classical MHC class I molecule HLA-E (and mouse Qa-1b), which presents leader sequence peptides from other HLA class I molecules, with CD94-NKG2A having higher HLA-E affinity than CD94-NKG2C, and inhibitory signaling proceeding through NKG2A ITIM phosphorylation, SHP-1 recruitment, and downstream disruption of the actin network and lipid raft organization at the immunological synapse to suppress NK and CTL cytotoxic effector functions.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"KLRD1 (CD94) is the invariant subunit of a family of heterodimeric NK- and T-cell receptors that survey cells for the non-classical MHC class I molecule HLA-E (mouse Qa-1b), thereby coupling detection of overall MHC class I integrity to control of cytotoxic effector function [#0, #5, #9]. CD94 is a C-type-lectin-fold glycoprotein whose structure is atypical — the second alpha-helix is replaced by a loop, the carbohydrate-binding site is altered, and the Ca2+ site is nonfunctional — and it assembles as a disulfide-linked dimer that pairs with NKG2 chains [#12, #38]. Disulfide-bonded heterodimers with NKG2A/B form inhibitory receptors carrying cytoplasmic ITIMs, whereas pairing with NKG2C/E generates activating receptors that lack ITIMs and instead associate noncovalently with the ITAM-bearing adaptor DAP12 through complementary transmembrane charged residues [#0, #2, #7, #10]. Crystal structures of CD94 alone, the CD94–NKG2A heterodimer, and the ternary CD94–NKG2A–HLA-E complex establish that the invariant CD94 chain dominates contact with HLA-E and its bound leader peptide in a lock-and-key mode, while the variable NKG2 chain lies peripheral; residues at the CD94–NKG2 interface (NKG2 167–170) account for the higher HLA-E affinity of the inhibitory CD94/NKG2A over the activating CD94/NKG2C [#18, #19, #20]. HLA-E recognition is strictly peptide-dependent, and subtle differences in the conformation of HLA class I leader peptides — only a subset of which are efficiently processed into functional epitopes — tune receptor engagement and the resulting NK response [#11, #21, #37]. Engagement of CD94/NKG2A by HLA-E triggers NKG2A ITIM tyrosine phosphorylation and SHP-1 recruitment, which blocks activation-receptor signaling (Syk/ZAP-70, Shc/Grb-2, ERK) and disrupts the actin network and lipid raft organization at the inhibitory immunological synapse, suppressing cytotoxicity [#8, #13, #17]. Through this inhibitory axis, CD94/NKG2A restrains NK and antigen-specific CD8+ T-cell cytotoxicity in viral infection and contributes, via the HLA-B→HLA-E→NKG2A education pathway, to healthy pregnancy [#30, #32, #35], while CD94/NKG2E serves as an activating receptor required for resistance to ectromelia virus [#26].\",\n  \"teleology\": [\n    {\n      \"year\": 1996,\n      \"claim\": \"Establishing that CD94 is not a stand-alone receptor but the shared subunit of a family of heterodimers explained how a single invariant chain could give rise to both inhibitory and activating signaling.\",\n      \"evidence\": \"Co-immunoprecipitation, SDS-PAGE, and cytoplasmic-domain sequencing of CD94 paired with NKG2A/B/C/E, plus serological and functional discrimination of inhibitory vs stimulatory forms\",\n      \"pmids\": [\"8943374\", \"8955184\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not identify the ligand of the heterodimers\", \"Did not define the structural basis of preferential heterodimer assembly\"]\n    },\n    {\n      \"year\": 1997,\n      \"claim\": \"Assigning the inhibitory function to the NKG2A/B ITIMs and showing CD94 is required for NKG2A surface maturation defined the molecular logic of the inhibitory receptor.\",\n      \"evidence\": \"Co-immunoprecipitation with anti-CD94, glycosylation maturation analysis, and ITIM sequence analysis on NK clones\",\n      \"pmids\": [\"9045931\", \"9034158\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not identify the recruited phosphatase\", \"Ligand still unknown\"]\n    },\n    {\n      \"year\": 1996,\n      \"claim\": \"Demonstrating divergent intracellular signaling distinguished the two receptor classes functionally before their ligand was known.\",\n      \"evidence\": \"Kinase activation and phosphorylation assays on sorted activating vs inhibitory NK clones after CD94 ligation\",\n      \"pmids\": [\"8816383\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Performed by antibody ligation rather than physiological ligand\", \"Phosphatase identity not yet pinned\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Identification of HLA-E (and mouse Qa-1b) as the ligand revealed that CD94/NKG2 receptors monitor global MHC class I status by reading leader-peptide-loaded non-classical class I.\",\n      \"evidence\": \"HLA-E and Qa-1b tetramer binding to transfectants and NK clones, leader-peptide loading, and antibody-blocked cytotoxicity assays\",\n      \"pmids\": [\"9486650\", \"9560253\", \"9815261\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not quantify affinity differences between inhibitory and activating receptors\", \"Atomic basis of recognition unresolved\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Showing that the activating CD94/NKG2C complex requires DAP12 through transmembrane charged residues explained how the ITIM-less activating receptors deliver positive signals.\",\n      \"evidence\": \"Co-immunoprecipitation and transmembrane-domain mutagenesis with surface expression analysis; later extended to T cells\",\n      \"pmids\": [\"9655483\", \"15940674\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"DAP12 downstream signaling steps for this receptor not fully traced\", \"T-cell co-IP evidence single lab (Medium)\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Linking HLA-E engagement to NKG2A phosphorylation and SHP-1 recruitment provided the proximal biochemical mechanism of inhibition.\",\n      \"evidence\": \"Tyrosine phosphorylation and SHP-1 co-immunoprecipitation in primary NK cells and RBL-2H3 reconstitution\",\n      \"pmids\": [\"9565368\", \"10570324\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Downstream substrates of SHP-1 not yet identified\", \"Xenoreactive study (10570324) single lab, Medium confidence\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Direct affinity measurement established that the inhibitory receptor binds HLA-E more strongly than the activating one, providing a kinetic basis for the dominance of inhibition.\",\n      \"evidence\": \"Surface plasmon resonance with soluble recombinant HLA-E and CD94/NKG2A vs CD94/NKG2C, correlated with NK functional assays\",\n      \"pmids\": [\"10428963\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural origin of the affinity difference not yet localized\", \"Single-lab kinetic measurement\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Defining the downstream inhibitory cascade showed how SHP-1 recruitment translates into blocked effector activation.\",\n      \"evidence\": \"Kinase, co-IP, and ERK activation assays demonstrating block of Syk, CD16-zeta phosphorylation, and Shc/Grb-2 complex formation; CD69-triggered ERK suppression in RBL transfectants\",\n      \"pmids\": [\"10358164\", \"10671222\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not address synapse-level cytoskeletal effects\", \"Reconstituted-system readouts\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"The first CD94 crystal structure revealed its atypical C-type lectin fold and a putative HLA-E binding surface, reframing CD94 as a lectin-like receptor that does not bind carbohydrate canonically.\",\n      \"evidence\": \"X-ray crystallography of the CD94 ectodomain at 2.6 Å\",\n      \"pmids\": [\"10023772\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structure of the heterodimer and the ligand complex not yet solved\", \"Functional carbohydrate/Ca2+ sites inferred, not tested\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Mutagenesis mapping showed inhibitory and activating receptors engage largely shared but partly distinct HLA-E surfaces, giving the first explanation for differential recognition.\",\n      \"evidence\": \"Alanine-scanning mutagenesis of HLA-E with binding to soluble CD94/NKG2A and CD94/NKG2C\",\n      \"pmids\": [\"14971033\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve which subunit contributes which contacts atomically\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Structures of the heterodimer and the ternary CD94–NKG2A–HLA-E complex established that the invariant CD94 chain dominates ligand contact and that NKG2 interface residues, not direct HLA-E contacts, set affinity differences.\",\n      \"evidence\": \"X-ray crystallography of CD94–NKG2A (2.5 Å), the ternary complex, and HLA-E/peptide structures, with interface mutagenesis\",\n      \"pmids\": [\"18083576\", \"18332182\", \"18448674\", \"18339401\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not connect binding to dynamics of signaling at the synapse\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Imaging the inhibitory synapse connected SHP-1 activity to physical disruption of the effector machinery, explaining how inhibition aborts killing.\",\n      \"evidence\": \"Confocal imaging, Vav1/ERM phosphorylation assays, and pharmacological actin and cholesterol perturbations at the inhibitory NK immunological synapse; earlier trafficking/recycling studies\",\n      \"pmids\": [\"16951318\", \"12444112\", \"15607803\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not fully resolve order of actin disruption vs raft exclusion in vivo\", \"Trafficking compartment identity partly defined\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Loss-of-function mouse genetics established the physiological roles and limits of CD94, showing it is dispensable for development yet required for the activating CD94/NKG2E response to a poxvirus.\",\n      \"evidence\": \"CD94-deficient and naturally CD94-deficient (DBA/2J) mouse models with viral and bacterial challenge, NK development, and tolerance assays\",\n      \"pmids\": [\"21439856\", \"21151939\", \"11782535\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Redundant inhibitory pathways masking phenotypes not fully mapped\", \"Allelic expression regulation (Medium) needs mechanism\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Inducible expression on CD8+ T cells demonstrated that the inhibitory receptor restrains antigen-specific CTL responses, extending CD94 biology beyond NK cells.\",\n      \"evidence\": \"In vivo polyoma virus infection with CD94/NKG2A blockade; IL-15- and TGF-β-driven induction of CD94/NKG2A on superantigen-stimulated T cells with functional blocking\",\n      \"pmids\": [\"11812997\", \"9448304\", \"9933082\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Transcriptional control of induction defined only by cytokine inputs (Medium)\", \"Consequences for tumor immunity not fully addressed here\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Pregnancy and exhaustion models linked the HLA-E→NKG2A axis to NK-cell education in reproduction and to a LAG-3/TOX-dependent cytotoxic subset of exhausted T cells, broadening physiological context.\",\n      \"evidence\": \"NKG2A-targeted KO crossed to wild-type males with placental/fetal phenotyping plus human GWAS; LAG-3 deletion in chronic LCMV with single-cell, TOX, and Qa-1b functional analysis\",\n      \"pmids\": [\"33887202\", \"39121847\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism linking NK education to vascular outcomes not fully resolved\", \"Human translation of exhaustion circuit inferred\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Systematic analysis of leader-peptide variants showed that only a subset of HLA signal peptides are efficiently processed into functional CD94/NKG2 epitopes, and competition among them tunes receptor engagement.\",\n      \"evidence\": \"Quantitative HLA-E surface expression and CD94/NKG2A/C engagement assays across 16 common signal-peptide variants with competitive loading; HLA-G allotype binding by ligand capture/reciprocal recombinant assays\",\n      \"pmids\": [\"37264229\", \"32575403\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Population-level consequences of variant repertoire not addressed\", \"HLA-G recognition single-lab (Medium)\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How CD94/NKG2 receptor surface levels, recycling, and ligand competition are integrated to set NK and T-cell activation thresholds in human disease and therapy remains incompletely defined.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No timeline evidence on regulation of receptor turnover during chronic human disease\", \"Therapeutic modulation of the axis not characterized in the corpus\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0001618\", \"supporting_discovery_ids\": [5, 9, 36]},\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [4, 8, 13]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 7, 18]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [8, 17, 23]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [3, 16, 31]},\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [16, 31]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [5, 8, 26, 32]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [4, 8, 13]}\n    ],\n    \"complexes\": [\n      \"CD94/NKG2A inhibitory receptor\",\n      \"CD94/NKG2C-DAP12 activating receptor\",\n      \"CD94/NKG2E activating receptor\"\n    ],\n    \"partners\": [\n      \"NKG2A\",\n      \"NKG2C\",\n      \"NKG2E\",\n      \"DAP12\",\n      \"HLA-E\",\n      \"SHP-1\",\n      \"Hsp70\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}