{"gene":"UBASH3B","run_date":"2026-04-28T21:43:00","timeline":{"discoveries":[{"year":2004,"finding":"Sts-1 (UBASH3B) and Sts-2 negatively regulate TCR signaling by suppressing ZAP-70 phosphorylation and activation; knockout mice show hyperresponsive T cells with increased Zap-70 phosphorylation (including ubiquitylated forms), hyperactivation of downstream signaling proteins, and increased cytokine production.","method":"Genetic knockout (Sts-1/2 double knockout mice), phosphorylation assays, cytokine measurement, EAE autoimmunity model","journal":"Immunity","confidence":"High","confidence_rationale":"Tier 2 — clean KO with defined cellular phenotype, replicated across multiple readouts, highly cited foundational paper","pmids":["14738763"],"is_preprint":false},{"year":2004,"finding":"Sts-1 (UBASH3B) interacts with Cbl via its SH3 domain, binds mono-ubiquitin via its UBA domain, is recruited into activated EGFR complexes, and inhibits EGFR and PDGFR endocytosis, thereby blocking receptor degradation and prolonging mitogenic signaling.","method":"Co-immunoprecipitation, domain-deletion constructs, receptor internalization assays, endocytic vesicle quantification, cell transformation assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP with domain mapping, multiple functional readouts, highly cited","pmids":["15159412"],"is_preprint":false},{"year":2007,"finding":"Sts-1 (UBASH3B) possesses intrinsic phosphatase activity via a PGM/acid phosphatase-like catalytic domain; it can dephosphorylate Zap-70, and point mutations impairing phosphatase activity in vitro also impair TCR signaling regulation in T cells.","method":"X-ray crystallography, in vitro phosphatase assays, active-site mutagenesis, T cell signaling assays","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 — crystal structure, in vitro reconstitution, mutagenesis, and cell-based functional validation","pmids":["17679096"],"is_preprint":false},{"year":2007,"finding":"Sts-1 (UBASH3B) catalyzes hydrolysis of ecdysteroid and steroid phosphates, demonstrating it is a member of the histidine phosphatase superfamily with phosphatase activity toward steroid substrates.","method":"Cloning, in vitro enzymatic assay with ecdysteroid/steroid phosphate substrates, structural homology modeling","journal":"Proteins","confidence":"Medium","confidence_rationale":"Tier 1 — in vitro enzymatic activity demonstrated, single lab","pmids":["17348005"],"is_preprint":false},{"year":2010,"finding":"TULA-2 (UBASH3B/Sts-1) associates with Syk and dephosphorylates it, negatively regulating GPVI-mediated platelet signaling; TULA-2 knockout mice show hyperphosphorylation of Syk and PLCγ2 and a prothrombotic phenotype with shortened bleeding times.","method":"Co-immunoprecipitation (TULA-2 with Syk), in vitro dephosphorylation assay, TULA-2 knockout mouse platelet functional assays, bleeding time measurement","journal":"Blood","confidence":"High","confidence_rationale":"Tier 2 — Co-IP plus KO with defined cellular and in vivo phenotype, multiple orthogonal methods","pmids":["20585042"],"is_preprint":false},{"year":2010,"finding":"TULA-2 (UBASH3B) has defined substrate specificity for phosphotyrosyl peptides: class I substrates have Pro at pY-1, class II substrates have acidic residues at pY-1 to pY-3; TULA-2 is highly active toward Syk pY323 and pY352 sites, and TULA-2 KO increases Syk phosphorylation at Y323 and Y352 in platelets.","method":"Combinatorial phosphotyrosyl peptide library screening, in vitro kinetic analysis, TULA-2 knockout platelets with phosphorylation site-specific immunoblotting","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — systematic library screen, kinetic assays, in vivo KO validation","pmids":["20670933"],"is_preprint":false},{"year":2012,"finding":"TULA-2 (UBASH3B) is recruited to phosphorylated C-terminal tyrosines of Syk in mast cells after FcεRI activation, and siRNA knockdown of TULA-2 increases Syk activation-loop phosphorylation, PLCγ2 phosphorylation, degranulation, and NF-κB/NFAT activation, establishing TULA-2 as a negative regulator of FcεRI signaling.","method":"Phosphopeptide pulldown with mass spectrometry identification, co-immunoprecipitation, far-Western blot, siRNA knockdown with functional degranulation assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — MS identification confirmed by Co-IP and far-Western, KD with multiple functional readouts","pmids":["22267732"],"is_preprint":false},{"year":2012,"finding":"TULA-2 (UBASH3B) is expressed in osteoclasts and negatively regulates osteoclast differentiation and function by dephosphorylating Syk at Y352 and Y525/526; phosphatase-dead TULA-2 mutant increases osteoclast function, and DKO mice show increased osteoclast numbers and decreased bone volume.","method":"Double knockout mouse skeletal analysis, in vitro osteoclast differentiation assay, phosphatase-dead mutant expression, site-specific Syk phosphorylation immunoblotting","journal":"Cellular and molecular life sciences","confidence":"High","confidence_rationale":"Tier 2 — KO phenotype, phosphatase-dead mutant, site-specific phosphorylation analysis, multiple orthogonal methods","pmids":["23149425"],"is_preprint":false},{"year":2013,"finding":"UBASH3B (Sts-1) dephosphorylates CBL ubiquitin ligase, leading to CBL inactivation and EGFR upregulation in triple-negative breast cancer; this phosphatase activity is required for UBASH3B's oncogenic promotion of invasion and metastasis.","method":"siRNA knockdown, phosphatase-dead mutant rescue experiments, EGFR expression and signaling assays, in vitro invasion/metastasis assays, mouse xenograft model","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 — loss-of-function with specific mechanistic readout (CBL phosphorylation/EGFR levels), phosphatase-dead mutant validation, in vivo model","pmids":["23784775"],"is_preprint":false},{"year":2013,"finding":"Sts-1 (UBASH3B) substrate-trapping mutants (H380A and E490A active site mutations) retain high-affinity binding to tyrosine-phosphorylated Zap-70, validating Zap-70 as a direct substrate of the Sts-1 phosphatase active site; overexpression of these trapping mutants in T cells blocks TCR signaling.","method":"Active-site mutagenesis, substrate-trapping from T cell lysates, vanadate competition, T cell functional signaling assay","journal":"The FEBS journal","confidence":"High","confidence_rationale":"Tier 1 — active-site mutagenesis with substrate-trapping, mechanistic validation in cells","pmids":["24256567"],"is_preprint":false},{"year":2015,"finding":"UBASH3B/Sts-1 is upregulated by AML1-ETO and supports proliferation of AML1-ETO leukemic cells partly by inhibiting CBL function; UBASH3B depletion induces aberrant CBL phosphorylation and growth impairment that can be rescued by CBL mutants.","method":"shRNA knockdown, rescue with CBL mutants, CBL phosphorylation analysis, xenograft model","journal":"Leukemia","confidence":"Medium","confidence_rationale":"Tier 2 — genetic epistasis (rescue by CBL mutants), single lab","pmids":["26449661"],"is_preprint":false},{"year":2015,"finding":"STS-1 (UBASH3B) promotes IFN-α-induced autophagy in B cells by inhibiting CBL-mediated phosphorylation, thereby enhancing TYK2 phosphorylation and activating the JAK1-STAT1 signaling pathway.","method":"Overexpression and knockdown experiments, CBL phosphorylation assays, JAK1/STAT1 pathway activation measurement, autophagy assay, JAK/STAT inhibitor treatment","journal":"European journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 — multiple pathway measurements with inhibitor validation, single lab","pmids":["25959715"],"is_preprint":false},{"year":2016,"finding":"UBASH3B acts as a ubiquitin receptor that binds ubiquitylated Aurora B kinase and controls Aurora B localization to mitotic microtubules prior to anaphase, which is necessary for proper timing and fidelity of chromosome segregation.","method":"Co-immunoprecipitation of ubiquitylated Aurora B with UBASH3B, live-cell imaging, loss-of-function and gain-of-function experiments, chromosome segregation assays","journal":"Developmental cell","confidence":"High","confidence_rationale":"Tier 2 — Co-IP of ubiquitylated substrate, live imaging of localization, LOF/GOF with defined mitotic phenotype, multiple orthogonal methods","pmids":["26766443"],"is_preprint":false},{"year":2016,"finding":"TULA-2 (UBASH3B) dephosphorylates Syk pY346 (a regulatory site phosphorylated early after receptor ligation) with high efficiency, and this dephosphorylation is the primary mechanism by which TULA-2 suppresses overall Syk activation downstream of GPVI-FcRγ in platelets.","method":"In vitro phosphatase assay with site-specific Syk phosphopeptides/proteins, TULA-2 KO platelet signaling analysis, site-specific phosphorylation immunoblotting","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — in vitro kinetic analysis of specific substrate site, KO validation in physiological context","pmids":["27609517"],"is_preprint":false},{"year":2016,"finding":"TULA-2 (UBASH3B) negatively regulates FcγRIIA-mediated platelet signaling by dephosphorylating Syk; TULA-2 knockout enhances Syk, LAT, and PLCγ2 phosphorylation and augments platelet aggregation, granule secretion, and phosphatidylserine exposure, and worsens heparin-induced thrombocytopenia in vivo.","method":"TULA-2 knockout mouse crossed with FcγRIIA transgenic mouse, platelet signaling and functional assays, in vivo HIT model, bleeding time measurement","journal":"Arteriosclerosis, thrombosis, and vascular biology","confidence":"High","confidence_rationale":"Tier 2 — genetic KO with multiple functional and in vivo readouts, multiple orthogonal methods","pmids":["27765766"],"is_preprint":false},{"year":2017,"finding":"Crystal structures of the histidine phosphatase domains of human Sts-1 and Sts-2 were determined (Sts-1HP unliganded at 2.5 Å and with sulfate at 1.9 Å; Sts-2HP with sulfate at 2.4 Å); Sts-1HP has significantly higher phosphatase activity than Sts-2HP; full-length Sts-1 and Sts-1HP show similar kinetics; PHPS1 (SHP-1 inhibitor) inhibits Sts-1 with Ki = 1.05 μM; Sts-1 has robust phosphatase activity against Zap-70 in a cell-based assay.","method":"X-ray crystallography, steady-state kinetics, inhibitor assays, cell-based phosphatase assay","journal":"Biochemistry","confidence":"High","confidence_rationale":"Tier 1 — crystal structures, in vitro kinetics, cell-based validation, multiple orthogonal methods","pmids":["28759203"],"is_preprint":false},{"year":2017,"finding":"STS-1 (UBASH3B) is identified as a novel binding partner of ShcA; the interaction is mediated via phosphotyrosine-containing peptides and is regulated by EGF receptor activation.","method":"Phosphotyrosyl peptide pulldown, mass spectrometry identification, EGF stimulation-dependent interaction assay","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 3 — peptide pulldown with MS identification, single lab, no functional follow-up","pmids":["28690151"],"is_preprint":false},{"year":2018,"finding":"TULA-2 (UBASH3B) deficiency enhances CLEC-2-mediated platelet aggregation and secretion by failing to dephosphorylate Syk Y346, leading to enhanced PLCγ2 and SLP-76 phosphorylation, establishing TULA-2 as a negative regulator of CLEC-2/HemITAM signaling via Syk Y346 dephosphorylation.","method":"TULA-2 knockout mouse platelets, CLEC-2 agonist stimulation, site-specific phosphorylation immunoblotting, platelet aggregation and secretion assays","journal":"TH open","confidence":"High","confidence_rationale":"Tier 2 — KO with site-specific phosphorylation readout and multiple functional assays","pmids":["31249969"],"is_preprint":false},{"year":2020,"finding":"TULA-2 (UBASH3B) negatively regulates Syk Y323 phosphorylation in endothelial cells; miR-25-3p suppresses TULA-2 expression, reducing TULA-2–Syk interaction and increasing Syk pY323, which elevates VEGFR-2 pY1175 and promotes angiogenesis.","method":"miR-25-3p overexpression/inhibition, TULA-2 protein expression analysis, Syk and VEGFR-2 phosphorylation immunoblotting, co-immunoprecipitation, in vitro angiogenesis assay, in vivo hindlimb ischemia model","journal":"Aging","confidence":"Medium","confidence_rationale":"Tier 2 — Co-IP and phosphorylation analysis with functional in vitro/in vivo readouts, single lab","pmids":["33201836"],"is_preprint":false},{"year":2021,"finding":"UBASH3B (Ubash3b) dephosphorylates PKCδ in leukemia cells treated with TPA, promoting PKCδ protein degradation via the proteasome; RNAi depletion of Ubash3b blocks TPA-induced PKCδ loss.","method":"RNAi knockdown, proteasome inhibitor treatment, PKCδ phosphorylation and protein level analysis, leukemia mouse model","journal":"Biochimie","confidence":"Medium","confidence_rationale":"Tier 2 — RNAi KD with specific mechanistic readout (PKCδ phosphorylation/degradation), single lab","pmids":["33556471"],"is_preprint":false},{"year":2024,"finding":"UBASH3B directly binds MRPL12 and dephosphorylates its tyrosine 60, which impedes MRPL12 binding to mitochondrial RNA polymerase POLRMT and downregulates mitochondrial oxidative phosphorylation, thereby inhibiting LUAD tumor progression.","method":"Mass spectrometry identification of phosphorylation site, co-immunoprecipitation (UBASH3B–MRPL12, MRPL12–POLRMT), Y60 phospho-mutant functional assays, in vitro/in vivo/organoid LUAD models","journal":"Journal of experimental & clinical cancer research","confidence":"Medium","confidence_rationale":"Tier 2 — MS-defined site, Co-IP, phospho-mutant validation in multiple model systems, single lab","pmids":["39343960"],"is_preprint":false}],"current_model":"UBASH3B (Sts-1/TULA-2) is a multi-domain protein containing UBA, SH3, and histidine phosphatase (PGM-like) domains that functions as a negative regulator of receptor tyrosine kinase and immune receptor signaling: it dephosphorylates key tyrosine kinase substrates including Syk (at pY346/pY352/pY323), ZAP-70, and CBL using a histidine-based catalytic mechanism, recruits to ubiquitylated proteins via its UBA domain (including ubiquitylated Aurora B to direct its mitotic localization), and suppresses receptor endocytosis by interacting with Cbl via its SH3 domain, collectively dampening TCR, GPVI, FcγRIIA, CLEC-2, and EGFR signaling while also controlling mitotic fidelity through Aurora B relocalization to microtubules."},"narrative":{"teleology":[{"year":2004,"claim":"The foundational question of whether UBASH3B participates in immune signaling was answered when Sts-1/Sts-2 double-knockout mice revealed hyperresponsive T cells with elevated ZAP-70 phosphorylation, establishing UBASH3B as a negative regulator of TCR signaling.","evidence":"Double-knockout mice with phosphorylation assays and cytokine measurement in T cells","pmids":["14738763"],"confidence":"High","gaps":["Individual Sts-1 versus Sts-2 contributions not fully separated","Mechanism of ZAP-70 dephosphorylation not yet identified","Whether phosphatase activity was direct was unknown"]},{"year":2004,"claim":"The domain architecture and non-immune functions were established when UBASH3B was shown to interact with Cbl via its SH3 domain and with mono-ubiquitin via its UBA domain, and to inhibit EGFR/PDGFR endocytosis, revealing a role in receptor trafficking beyond TCR signaling.","evidence":"Reciprocal co-immunoprecipitation with domain-deletion constructs, receptor internalization assays","pmids":["15159412"],"confidence":"High","gaps":["Whether the effect on endocytosis was phosphatase-dependent was unknown","In vivo relevance of receptor trafficking regulation not tested"]},{"year":2007,"claim":"A critical mechanistic question — whether UBASH3B acts as a phosphatase or an adaptor — was resolved by crystal structure determination and in vitro reconstitution showing intrinsic phosphatase activity through a histidine-based PGM-like catalytic domain, with active-site mutations impairing both enzymatic activity and TCR signaling regulation.","evidence":"X-ray crystallography, in vitro phosphatase assays, active-site mutagenesis with T cell signaling readouts","pmids":["17679096","17348005"],"confidence":"High","gaps":["Physiological substrates beyond ZAP-70 not yet defined","Substrate specificity determinants unknown"]},{"year":2010,"claim":"UBASH3B's role was extended beyond T cells when it was shown to associate with and dephosphorylate Syk in platelets, negatively regulating GPVI signaling, and systematic peptide library screening defined two substrate-specificity classes and identified Syk pY323 and pY352 as preferred target sites.","evidence":"TULA-2 KO mouse platelet assays, in vitro dephosphorylation, combinatorial phosphopeptide library screening with kinetic analysis","pmids":["20585042","20670933"],"confidence":"High","gaps":["Which Syk phosphosite is the primary regulatory target in vivo was unresolved","Role in other ITAM/hemITAM receptor pathways not yet tested"]},{"year":2012,"claim":"The range of immune receptors regulated by UBASH3B expanded further with demonstration that it is recruited to phosphorylated Syk C-terminal tyrosines in mast cells after FcεRI activation and suppresses degranulation and NF-κB/NFAT activation, while in bone it was shown to regulate osteoclastogenesis through Syk dephosphorylation at Y352 and Y525/526.","evidence":"Phosphopeptide pulldown with MS, siRNA knockdown in mast cells; DKO mouse skeletal analysis with phosphatase-dead mutant in osteoclasts","pmids":["22267732","23149425"],"confidence":"High","gaps":["How UBASH3B is recruited to distinct receptor complexes remained unclear","Relative importance of different Syk phosphosites across cell types unresolved"]},{"year":2013,"claim":"A direct phosphatase–substrate relationship was validated when substrate-trapping mutants (H380A, E490A) retained high-affinity binding to phospho-ZAP-70, and UBASH3B was shown to dephosphorylate CBL, inactivating its E3 ligase function and upregulating EGFR to promote breast cancer invasion and metastasis.","evidence":"Active-site substrate-trapping mutagenesis in T cells; siRNA/phosphatase-dead mutant rescue in TNBC cells with xenograft model","pmids":["24256567","23784775"],"confidence":"High","gaps":["Full catalogue of UBASH3B substrates beyond ZAP-70, Syk, and CBL unknown","Whether CBL dephosphorylation occurs in normal physiology not addressed"]},{"year":2016,"claim":"The primary regulatory mechanism in platelets was pinpointed to dephosphorylation of Syk pY346, and UBASH3B's role was extended to FcγRIIA signaling where its loss worsened heparin-induced thrombocytopenia; concurrently, a non-phosphatase function was discovered in which UBASH3B's UBA domain binds ubiquitylated Aurora B to control its mitotic localization and chromosome segregation fidelity.","evidence":"In vitro kinetics with site-specific phosphopeptides and KO platelet analysis; FcγRIIA-transgenic/TULA-2-KO mice with in vivo HIT model; Co-IP of ubiquitylated Aurora B, live-cell imaging, LOF/GOF mitotic assays","pmids":["27609517","27765766","26766443"],"confidence":"High","gaps":["Whether the UBA-mediated mitotic function requires phosphatase activity is unknown","Structural basis of Aurora B ubiquitin recognition not determined","Clinical relevance of UBASH3B in thrombotic disease not established"]},{"year":2017,"claim":"High-resolution crystal structures of the Sts-1 and Sts-2 histidine phosphatase domains explained the ~100-fold activity difference between paralogs and identified PHPS1 as a micromolar inhibitor, providing a structural framework for selective targeting.","evidence":"X-ray crystallography at 1.9–2.5 Å resolution, steady-state kinetics, inhibitor Ki determination","pmids":["28759203"],"confidence":"High","gaps":["No co-crystal with a phosphotyrosine substrate exists","Selectivity of PHPS1 for UBASH3B over other histidine phosphatases not fully profiled"]},{"year":2018,"claim":"UBASH3B's role as a universal negative regulator of Syk-dependent signaling was consolidated when CLEC-2/hemITAM pathway activation was shown to be enhanced in TULA-2 KO platelets through failure to dephosphorylate Syk Y346.","evidence":"TULA-2 KO mouse platelets stimulated with CLEC-2 agonist, site-specific phosphorylation and functional aggregation assays","pmids":["31249969"],"confidence":"High","gaps":["Whether UBASH3B regulation of CLEC-2 signaling is relevant in lymphatic development not tested"]},{"year":2020,"claim":"UBASH3B function was extended to endothelial biology when miR-25-3p–mediated suppression of TULA-2 was shown to increase Syk pY323 and VEGFR-2 pY1175 phosphorylation, promoting angiogenesis in vitro and in vivo.","evidence":"miR-25-3p overexpression/inhibition, Co-IP of TULA-2–Syk, VEGFR-2 phosphorylation analysis, hindlimb ischemia model","pmids":["33201836"],"confidence":"Medium","gaps":["Direct dephosphorylation of VEGFR-2 by UBASH3B not demonstrated","Single-lab observation","Endogenous miR-25-3p regulation of UBASH3B in disease contexts not validated"]},{"year":2021,"claim":"The substrate repertoire was further broadened when UBASH3B was found to dephosphorylate PKCδ, promoting its proteasomal degradation in leukemia cells treated with TPA.","evidence":"RNAi knockdown with proteasome inhibitor treatment, PKCδ phosphorylation and stability analysis","pmids":["33556471"],"confidence":"Medium","gaps":["Specific PKCδ phosphosite targeted by UBASH3B not identified","Not independently replicated"]},{"year":2024,"claim":"A mitochondrial function was uncovered when UBASH3B was shown to directly bind and dephosphorylate MRPL12 at Y60, disrupting the MRPL12–POLRMT interaction and downregulating mitochondrial oxidative phosphorylation to suppress lung adenocarcinoma progression.","evidence":"MS-identified phosphosite, Co-IP, Y60 phosphomutant studies in LUAD cell lines, xenografts, and organoids","pmids":["39343960"],"confidence":"Medium","gaps":["Whether UBASH3B enters mitochondria or acts before import is unclear","Single-lab finding awaiting replication","In vivo relevance in normal mitochondrial physiology not tested"]},{"year":null,"claim":"Key unresolved questions include how UBASH3B's phosphatase and ubiquitin-binding functions are coordinated, what determines substrate selectivity across diverse receptor systems, and whether UBASH3B can be therapeutically targeted to modulate thrombosis or anti-tumor immunity.","evidence":"","pmids":[],"confidence":"Low","gaps":["No co-crystal structure with a physiological phosphotyrosine substrate","Integration of UBA-mediated and phosphatase-mediated functions not mechanistically resolved","No selective high-potency inhibitor or activator reported"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[2,4,5,6,7,8,9,13,14,15,17,19,20]},{"term_id":"GO:0016787","term_label":"hydrolase activity","supporting_discovery_ids":[2,3,5,15]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[1,9]},{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[12]},{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[20]}],"pathway":[{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[0,6,9,14,17]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[1,8,18,20]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[12]},{"term_id":"R-HSA-109582","term_label":"Hemostasis","supporting_discovery_ids":[4,13,14]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[20]}],"complexes":[],"partners":["SYK","ZAP70","CBL","AURKB","MRPL12","SHC1","EGFR"],"other_free_text":[]},"mechanistic_narrative":"UBASH3B (Sts-1/TULA-2) is a multi-domain tyrosine phosphatase of the histidine phosphatase superfamily that broadly attenuates receptor-proximal signaling by dephosphorylating activated tyrosine kinases and their substrates. Its PGM-like catalytic domain dephosphorylates Syk (at pY346, pY352, pY323, pY525/526) and ZAP-70 to negatively regulate TCR, GPVI, FcγRIIA, FcεRI, and CLEC-2 signaling, and knockout mice exhibit hyperresponsive T cells, hyperactive platelets with a prothrombotic phenotype, and increased osteoclast numbers with reduced bone volume [PMID:14738763, PMID:20585042, PMID:27609517, PMID:23149425]. UBASH3B also dephosphorylates CBL ubiquitin ligase, stabilizing EGFR at the cell surface and promoting invasion in triple-negative breast cancer, and dephosphorylates MRPL12 to regulate mitochondrial transcription and oxidative phosphorylation [PMID:23784775, PMID:39343960]. Beyond its phosphatase function, UBASH3B acts as a ubiquitin receptor through its UBA domain, binding ubiquitylated Aurora B kinase to direct its relocalization to mitotic microtubules and ensure chromosome segregation fidelity [PMID:26766443]."},"prefetch_data":{"uniprot":{"accession":"Q8TF42","full_name":"Ubiquitin-associated and SH3 domain-containing protein B","aliases":["Cbl-interacting protein p70","Suppressor of T-cell receptor signaling 1","STS-1","T-cell ubiquitin ligand 2","TULA-2","Tyrosine-protein phosphatase STS1/TULA2"],"length_aa":649,"mass_kda":72.7,"function":"Interferes with CBL-mediated down-regulation and degradation of receptor-type tyrosine kinases. Promotes accumulation of activated target receptors, such as T-cell receptors and EGFR, on the cell surface. Exhibits tyrosine phosphatase activity toward several substrates including EGFR, FAK, SYK, and ZAP70. Down-regulates proteins that are dually modified by both protein tyrosine phosphorylation and ubiquitination","subcellular_location":"Cytoplasm; Nucleus","url":"https://www.uniprot.org/uniprotkb/Q8TF42/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/UBASH3B","classification":"Not Classified","n_dependent_lines":4,"n_total_lines":1208,"dependency_fraction":0.0033112582781456954},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/UBASH3B","total_profiled":1310},"omim":[{"mim_id":"615951","title":"ZINC FINGER SWIM DOMAIN-CONTAINING PROTEIN 6; ZSWIM6","url":"https://www.omim.org/entry/615951"},{"mim_id":"609201","title":"UBIQUITIN-ASSOCIATED AND SH3 DOMAIN-CONTAINING PROTEIN B; UBASH3B","url":"https://www.omim.org/entry/609201"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Cytosol","reliability":"Approved"},{"location":"Nucleoplasm","reliability":"Additional"},{"location":"Nuclear bodies","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"brain","ntpm":21.2},{"tissue":"lymphoid tissue","ntpm":14.7},{"tissue":"placenta","ntpm":12.9}],"url":"https://www.proteinatlas.org/search/UBASH3B"},"hgnc":{"alias_symbol":["KIAA1959","STS-1","TULA2","TULA-2"],"prev_symbol":[]},"alphafold":{"accession":"Q8TF42","domains":[{"cath_id":"-","chopping":"44-77","consensus_level":"high","plddt":95.2115,"start":44,"end":77},{"cath_id":"3.90.1140.10","chopping":"89-254_321-331","consensus_level":"high","plddt":93.0992,"start":89,"end":331},{"cath_id":"2.30.30.40","chopping":"264-313","consensus_level":"medium","plddt":88.7202,"start":264,"end":313},{"cath_id":"3.40.50.1240","chopping":"385-394_439-626","consensus_level":"high","plddt":95.5055,"start":385,"end":626}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8TF42","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8TF42-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8TF42-F1-predicted_aligned_error_v6.png","plddt_mean":84.94},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=UBASH3B","jax_strain_url":"https://www.jax.org/strain/search?query=UBASH3B"},"sequence":{"accession":"Q8TF42","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8TF42.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8TF42/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8TF42"}},"corpus_meta":[{"pmid":"14738763","id":"PMC_14738763","title":"Regulation of ZAP-70 activation and TCR signaling by two related proteins, Sts-1 and Sts-2.","date":"2004","source":"Immunity","url":"https://pubmed.ncbi.nlm.nih.gov/14738763","citation_count":152,"is_preprint":false},{"pmid":"15159412","id":"PMC_15159412","title":"Suppressors of T-cell receptor signaling Sts-1 and Sts-2 bind to Cbl and inhibit endocytosis of receptor tyrosine kinases.","date":"2004","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/15159412","citation_count":119,"is_preprint":false},{"pmid":"17679096","id":"PMC_17679096","title":"A phosphatase activity of Sts-1 contributes to the suppression of TCR signaling.","date":"2007","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/17679096","citation_count":100,"is_preprint":false},{"pmid":"23784775","id":"PMC_23784775","title":"Protein tyrosine phosphatase UBASH3B is overexpressed in triple-negative breast cancer and promotes invasion and metastasis.","date":"2013","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/23784775","citation_count":63,"is_preprint":false},{"pmid":"20585042","id":"PMC_20585042","title":"A novel histidine tyrosine phosphatase, TULA-2, associates with Syk and negatively regulates GPVI signaling in platelets.","date":"2010","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/20585042","citation_count":61,"is_preprint":false},{"pmid":"20670933","id":"PMC_20670933","title":"Determination of the substrate specificity of protein-tyrosine phosphatase TULA-2 and identification of Syk as a TULA-2 substrate.","date":"2010","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/20670933","citation_count":49,"is_preprint":false},{"pmid":"26449661","id":"PMC_26449661","title":"UBASH3B/Sts-1-CBL axis regulates myeloid proliferation in human preleukemia induced by AML1-ETO.","date":"2015","source":"Leukemia","url":"https://pubmed.ncbi.nlm.nih.gov/26449661","citation_count":48,"is_preprint":false},{"pmid":"22267732","id":"PMC_22267732","title":"Once phosphorylated, tyrosines in carboxyl terminus of protein-tyrosine kinase Syk interact with signaling proteins, including TULA-2, a negative regulator of mast cell degranulation.","date":"2012","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/22267732","citation_count":37,"is_preprint":false},{"pmid":"26766443","id":"PMC_26766443","title":"Ubiquitin Receptor Protein UBASH3B Drives Aurora B Recruitment to Mitotic Microtubules.","date":"2016","source":"Developmental cell","url":"https://pubmed.ncbi.nlm.nih.gov/26766443","citation_count":35,"is_preprint":false},{"pmid":"23149425","id":"PMC_23149425","title":"TULA-2, a novel histidine phosphatase, regulates bone remodeling by modulating osteoclast function.","date":"2012","source":"Cellular and molecular life sciences : CMLS","url":"https://pubmed.ncbi.nlm.nih.gov/23149425","citation_count":33,"is_preprint":false},{"pmid":"25959715","id":"PMC_25959715","title":"STS-1 promotes IFN-α induced autophagy by activating the JAK1-STAT1 signaling pathway in B cells.","date":"2015","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/25959715","citation_count":31,"is_preprint":false},{"pmid":"6661134","id":"PMC_6661134","title":"Medical results from STS 1-4: analysis of body fluids.","date":"1983","source":"Aviation, space, and environmental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/6661134","citation_count":29,"is_preprint":false},{"pmid":"27609517","id":"PMC_27609517","title":"TULA-2 Protein Phosphatase Suppresses Activation of Syk through the GPVI Platelet Receptor for Collagen by Dephosphorylating Tyr(P)346, a Regulatory Site of Syk.","date":"2016","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/27609517","citation_count":28,"is_preprint":false},{"pmid":"24256567","id":"PMC_24256567","title":"Insights into the suppressor of T-cell receptor (TCR) signaling-1 (Sts-1)-mediated regulation of TCR signaling through the use of novel substrate-trapping Sts-1 phosphatase variants.","date":"2013","source":"The FEBS journal","url":"https://pubmed.ncbi.nlm.nih.gov/24256567","citation_count":21,"is_preprint":false},{"pmid":"17348005","id":"PMC_17348005","title":"An unsuspected ecdysteroid/steroid phosphatase activity in the key T-cell regulator, Sts-1: surprising relationship to insect ecdysteroid phosphate phosphatase.","date":"2007","source":"Proteins","url":"https://pubmed.ncbi.nlm.nih.gov/17348005","citation_count":20,"is_preprint":false},{"pmid":"27765766","id":"PMC_27765766","title":"TULA-2 (T-Cell Ubiquitin Ligand-2) Inhibits the Platelet Fc Receptor for IgG IIA (FcγRIIA) Signaling Pathway and Heparin-Induced Thrombocytopenia in Mice.","date":"2016","source":"Arteriosclerosis, thrombosis, and vascular biology","url":"https://pubmed.ncbi.nlm.nih.gov/27765766","citation_count":20,"is_preprint":false},{"pmid":"33201836","id":"PMC_33201836","title":"miR-25-3p promotes endothelial cell angiogenesis in aging mice via TULA-2/SYK/VEGFR-2 downregulation.","date":"2020","source":"Aging","url":"https://pubmed.ncbi.nlm.nih.gov/33201836","citation_count":13,"is_preprint":false},{"pmid":"28759203","id":"PMC_28759203","title":"Structural and Functional Characterization of the Histidine Phosphatase Domains of Human Sts-1 and Sts-2.","date":"2017","source":"Biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/28759203","citation_count":13,"is_preprint":false},{"pmid":"39343960","id":"PMC_39343960","title":"UBASH3B-mediated MRPL12 Y60 dephosphorylation inhibits LUAD development by driving mitochondrial metabolism reprogramming.","date":"2024","source":"Journal of experimental & clinical cancer research : CR","url":"https://pubmed.ncbi.nlm.nih.gov/39343960","citation_count":12,"is_preprint":false},{"pmid":"31249969","id":"PMC_31249969","title":"TULA-2 Deficiency Enhances Platelet Functional Responses to CLEC-2 Agonists.","date":"2018","source":"TH open : companion journal to thrombosis and haemostasis","url":"https://pubmed.ncbi.nlm.nih.gov/31249969","citation_count":12,"is_preprint":false},{"pmid":"16511305","id":"PMC_16511305","title":"Crystallization and initial crystal characterization of the C-terminal phosphoglycerate mutase homology domain of Sts-1.","date":"2006","source":"Acta crystallographica. Section F, Structural biology and crystallization communications","url":"https://pubmed.ncbi.nlm.nih.gov/16511305","citation_count":12,"is_preprint":false},{"pmid":"38461240","id":"PMC_38461240","title":"FLI1 induces erythroleukemia through opposing effects on UBASH3A and UBASH3B expression.","date":"2024","source":"BMC cancer","url":"https://pubmed.ncbi.nlm.nih.gov/38461240","citation_count":8,"is_preprint":false},{"pmid":"28690151","id":"PMC_28690151","title":"Identification of STS-1 as a novel ShcA-binding protein.","date":"2017","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/28690151","citation_count":8,"is_preprint":false},{"pmid":"29487893","id":"PMC_29487893","title":"UBASH3B-mediated silencing of the mitotic checkpoint: Therapeutic perspectives in cancer.","date":"2017","source":"Molecular & cellular oncology","url":"https://pubmed.ncbi.nlm.nih.gov/29487893","citation_count":8,"is_preprint":false},{"pmid":"33556471","id":"PMC_33556471","title":"Ubash3b promotes TPA-mediated suppression of leukemogenesis through accelerated downregulation of PKCδ protein.","date":"2021","source":"Biochimie","url":"https://pubmed.ncbi.nlm.nih.gov/33556471","citation_count":7,"is_preprint":false},{"pmid":"30289285","id":"PMC_30289285","title":"Ubiquitin Associated and SH3 Domain Containing B (UBASH3B) Gene Association with Behcet's Disease in Iranian Population.","date":"2018","source":"Current eye research","url":"https://pubmed.ncbi.nlm.nih.gov/30289285","citation_count":6,"is_preprint":false},{"pmid":"29492198","id":"PMC_29492198","title":"UBASH3B promotes tamoxifen resistance and could be negatively regulated by ESR1.","date":"2017","source":"Oncotarget","url":"https://pubmed.ncbi.nlm.nih.gov/29492198","citation_count":6,"is_preprint":false},{"pmid":"24587276","id":"PMC_24587276","title":"Enhanced response of T cells from murine gammaherpesvirus 68-infected mice lacking the suppressor of T cell receptor signaling molecules Sts-1 and Sts-2.","date":"2014","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/24587276","citation_count":4,"is_preprint":false},{"pmid":"37298164","id":"PMC_37298164","title":"STS-1 and STS-2, Multi-Enzyme Proteins Equipped to Mediate Protein-Protein Interactions.","date":"2023","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/37298164","citation_count":3,"is_preprint":false},{"pmid":"6700189","id":"PMC_6700189","title":"[Medical results from STS 1-4: analysis of body fluids].","date":"1984","source":"Kosmicheskaia biologiia i aviakosmicheskaia meditsina","url":"https://pubmed.ncbi.nlm.nih.gov/6700189","citation_count":2,"is_preprint":false},{"pmid":"40885971","id":"PMC_40885971","title":"Investigating the role of UBASH3B in cancer: structural relevance, physiological functions, and therapeutic possibilities.","date":"2025","source":"Journal of experimental & clinical cancer research : CR","url":"https://pubmed.ncbi.nlm.nih.gov/40885971","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.04.09.648028","title":"Rapid expansion of synaptic complexity as a key contributor to cognitive growth in early humans","date":"2025-04-15","source":"bioRxiv","url":"https://doi.org/10.1101/2025.04.09.648028","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2025.03.13.25323837","title":"Interrogating DNA methylation associated with Lewy body pathology in a cross brain-region and multi-cohort study","date":"2025-03-14","source":"bioRxiv","url":"https://doi.org/10.1101/2025.03.13.25323837","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":17345,"output_tokens":5128,"usd":0.064477},"stage2":{"model":"claude-opus-4-6","input_tokens":8717,"output_tokens":3489,"usd":0.196215},"total_usd":0.260692,"stage1_batch_id":"msgbatch_01RPbVc9PDH9zQmYK5Hs6srm","stage2_batch_id":"msgbatch_01JVbVLzeKN2yVrsGp3zC8aM","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2004,\n      \"finding\": \"Sts-1 (UBASH3B) and Sts-2 negatively regulate TCR signaling by suppressing ZAP-70 phosphorylation and activation; knockout mice show hyperresponsive T cells with increased Zap-70 phosphorylation (including ubiquitylated forms), hyperactivation of downstream signaling proteins, and increased cytokine production.\",\n      \"method\": \"Genetic knockout (Sts-1/2 double knockout mice), phosphorylation assays, cytokine measurement, EAE autoimmunity model\",\n      \"journal\": \"Immunity\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with defined cellular phenotype, replicated across multiple readouts, highly cited foundational paper\",\n      \"pmids\": [\"14738763\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Sts-1 (UBASH3B) interacts with Cbl via its SH3 domain, binds mono-ubiquitin via its UBA domain, is recruited into activated EGFR complexes, and inhibits EGFR and PDGFR endocytosis, thereby blocking receptor degradation and prolonging mitogenic signaling.\",\n      \"method\": \"Co-immunoprecipitation, domain-deletion constructs, receptor internalization assays, endocytic vesicle quantification, cell transformation assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP with domain mapping, multiple functional readouts, highly cited\",\n      \"pmids\": [\"15159412\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Sts-1 (UBASH3B) possesses intrinsic phosphatase activity via a PGM/acid phosphatase-like catalytic domain; it can dephosphorylate Zap-70, and point mutations impairing phosphatase activity in vitro also impair TCR signaling regulation in T cells.\",\n      \"method\": \"X-ray crystallography, in vitro phosphatase assays, active-site mutagenesis, T cell signaling assays\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure, in vitro reconstitution, mutagenesis, and cell-based functional validation\",\n      \"pmids\": [\"17679096\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Sts-1 (UBASH3B) catalyzes hydrolysis of ecdysteroid and steroid phosphates, demonstrating it is a member of the histidine phosphatase superfamily with phosphatase activity toward steroid substrates.\",\n      \"method\": \"Cloning, in vitro enzymatic assay with ecdysteroid/steroid phosphate substrates, structural homology modeling\",\n      \"journal\": \"Proteins\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 — in vitro enzymatic activity demonstrated, single lab\",\n      \"pmids\": [\"17348005\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"TULA-2 (UBASH3B/Sts-1) associates with Syk and dephosphorylates it, negatively regulating GPVI-mediated platelet signaling; TULA-2 knockout mice show hyperphosphorylation of Syk and PLCγ2 and a prothrombotic phenotype with shortened bleeding times.\",\n      \"method\": \"Co-immunoprecipitation (TULA-2 with Syk), in vitro dephosphorylation assay, TULA-2 knockout mouse platelet functional assays, bleeding time measurement\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP plus KO with defined cellular and in vivo phenotype, multiple orthogonal methods\",\n      \"pmids\": [\"20585042\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"TULA-2 (UBASH3B) has defined substrate specificity for phosphotyrosyl peptides: class I substrates have Pro at pY-1, class II substrates have acidic residues at pY-1 to pY-3; TULA-2 is highly active toward Syk pY323 and pY352 sites, and TULA-2 KO increases Syk phosphorylation at Y323 and Y352 in platelets.\",\n      \"method\": \"Combinatorial phosphotyrosyl peptide library screening, in vitro kinetic analysis, TULA-2 knockout platelets with phosphorylation site-specific immunoblotting\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — systematic library screen, kinetic assays, in vivo KO validation\",\n      \"pmids\": [\"20670933\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"TULA-2 (UBASH3B) is recruited to phosphorylated C-terminal tyrosines of Syk in mast cells after FcεRI activation, and siRNA knockdown of TULA-2 increases Syk activation-loop phosphorylation, PLCγ2 phosphorylation, degranulation, and NF-κB/NFAT activation, establishing TULA-2 as a negative regulator of FcεRI signaling.\",\n      \"method\": \"Phosphopeptide pulldown with mass spectrometry identification, co-immunoprecipitation, far-Western blot, siRNA knockdown with functional degranulation assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — MS identification confirmed by Co-IP and far-Western, KD with multiple functional readouts\",\n      \"pmids\": [\"22267732\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"TULA-2 (UBASH3B) is expressed in osteoclasts and negatively regulates osteoclast differentiation and function by dephosphorylating Syk at Y352 and Y525/526; phosphatase-dead TULA-2 mutant increases osteoclast function, and DKO mice show increased osteoclast numbers and decreased bone volume.\",\n      \"method\": \"Double knockout mouse skeletal analysis, in vitro osteoclast differentiation assay, phosphatase-dead mutant expression, site-specific Syk phosphorylation immunoblotting\",\n      \"journal\": \"Cellular and molecular life sciences\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — KO phenotype, phosphatase-dead mutant, site-specific phosphorylation analysis, multiple orthogonal methods\",\n      \"pmids\": [\"23149425\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"UBASH3B (Sts-1) dephosphorylates CBL ubiquitin ligase, leading to CBL inactivation and EGFR upregulation in triple-negative breast cancer; this phosphatase activity is required for UBASH3B's oncogenic promotion of invasion and metastasis.\",\n      \"method\": \"siRNA knockdown, phosphatase-dead mutant rescue experiments, EGFR expression and signaling assays, in vitro invasion/metastasis assays, mouse xenograft model\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — loss-of-function with specific mechanistic readout (CBL phosphorylation/EGFR levels), phosphatase-dead mutant validation, in vivo model\",\n      \"pmids\": [\"23784775\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Sts-1 (UBASH3B) substrate-trapping mutants (H380A and E490A active site mutations) retain high-affinity binding to tyrosine-phosphorylated Zap-70, validating Zap-70 as a direct substrate of the Sts-1 phosphatase active site; overexpression of these trapping mutants in T cells blocks TCR signaling.\",\n      \"method\": \"Active-site mutagenesis, substrate-trapping from T cell lysates, vanadate competition, T cell functional signaling assay\",\n      \"journal\": \"The FEBS journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — active-site mutagenesis with substrate-trapping, mechanistic validation in cells\",\n      \"pmids\": [\"24256567\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"UBASH3B/Sts-1 is upregulated by AML1-ETO and supports proliferation of AML1-ETO leukemic cells partly by inhibiting CBL function; UBASH3B depletion induces aberrant CBL phosphorylation and growth impairment that can be rescued by CBL mutants.\",\n      \"method\": \"shRNA knockdown, rescue with CBL mutants, CBL phosphorylation analysis, xenograft model\",\n      \"journal\": \"Leukemia\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis (rescue by CBL mutants), single lab\",\n      \"pmids\": [\"26449661\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"STS-1 (UBASH3B) promotes IFN-α-induced autophagy in B cells by inhibiting CBL-mediated phosphorylation, thereby enhancing TYK2 phosphorylation and activating the JAK1-STAT1 signaling pathway.\",\n      \"method\": \"Overexpression and knockdown experiments, CBL phosphorylation assays, JAK1/STAT1 pathway activation measurement, autophagy assay, JAK/STAT inhibitor treatment\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple pathway measurements with inhibitor validation, single lab\",\n      \"pmids\": [\"25959715\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"UBASH3B acts as a ubiquitin receptor that binds ubiquitylated Aurora B kinase and controls Aurora B localization to mitotic microtubules prior to anaphase, which is necessary for proper timing and fidelity of chromosome segregation.\",\n      \"method\": \"Co-immunoprecipitation of ubiquitylated Aurora B with UBASH3B, live-cell imaging, loss-of-function and gain-of-function experiments, chromosome segregation assays\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP of ubiquitylated substrate, live imaging of localization, LOF/GOF with defined mitotic phenotype, multiple orthogonal methods\",\n      \"pmids\": [\"26766443\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"TULA-2 (UBASH3B) dephosphorylates Syk pY346 (a regulatory site phosphorylated early after receptor ligation) with high efficiency, and this dephosphorylation is the primary mechanism by which TULA-2 suppresses overall Syk activation downstream of GPVI-FcRγ in platelets.\",\n      \"method\": \"In vitro phosphatase assay with site-specific Syk phosphopeptides/proteins, TULA-2 KO platelet signaling analysis, site-specific phosphorylation immunoblotting\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro kinetic analysis of specific substrate site, KO validation in physiological context\",\n      \"pmids\": [\"27609517\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"TULA-2 (UBASH3B) negatively regulates FcγRIIA-mediated platelet signaling by dephosphorylating Syk; TULA-2 knockout enhances Syk, LAT, and PLCγ2 phosphorylation and augments platelet aggregation, granule secretion, and phosphatidylserine exposure, and worsens heparin-induced thrombocytopenia in vivo.\",\n      \"method\": \"TULA-2 knockout mouse crossed with FcγRIIA transgenic mouse, platelet signaling and functional assays, in vivo HIT model, bleeding time measurement\",\n      \"journal\": \"Arteriosclerosis, thrombosis, and vascular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO with multiple functional and in vivo readouts, multiple orthogonal methods\",\n      \"pmids\": [\"27765766\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Crystal structures of the histidine phosphatase domains of human Sts-1 and Sts-2 were determined (Sts-1HP unliganded at 2.5 Å and with sulfate at 1.9 Å; Sts-2HP with sulfate at 2.4 Å); Sts-1HP has significantly higher phosphatase activity than Sts-2HP; full-length Sts-1 and Sts-1HP show similar kinetics; PHPS1 (SHP-1 inhibitor) inhibits Sts-1 with Ki = 1.05 μM; Sts-1 has robust phosphatase activity against Zap-70 in a cell-based assay.\",\n      \"method\": \"X-ray crystallography, steady-state kinetics, inhibitor assays, cell-based phosphatase assay\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structures, in vitro kinetics, cell-based validation, multiple orthogonal methods\",\n      \"pmids\": [\"28759203\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"STS-1 (UBASH3B) is identified as a novel binding partner of ShcA; the interaction is mediated via phosphotyrosine-containing peptides and is regulated by EGF receptor activation.\",\n      \"method\": \"Phosphotyrosyl peptide pulldown, mass spectrometry identification, EGF stimulation-dependent interaction assay\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — peptide pulldown with MS identification, single lab, no functional follow-up\",\n      \"pmids\": [\"28690151\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"TULA-2 (UBASH3B) deficiency enhances CLEC-2-mediated platelet aggregation and secretion by failing to dephosphorylate Syk Y346, leading to enhanced PLCγ2 and SLP-76 phosphorylation, establishing TULA-2 as a negative regulator of CLEC-2/HemITAM signaling via Syk Y346 dephosphorylation.\",\n      \"method\": \"TULA-2 knockout mouse platelets, CLEC-2 agonist stimulation, site-specific phosphorylation immunoblotting, platelet aggregation and secretion assays\",\n      \"journal\": \"TH open\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — KO with site-specific phosphorylation readout and multiple functional assays\",\n      \"pmids\": [\"31249969\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"TULA-2 (UBASH3B) negatively regulates Syk Y323 phosphorylation in endothelial cells; miR-25-3p suppresses TULA-2 expression, reducing TULA-2–Syk interaction and increasing Syk pY323, which elevates VEGFR-2 pY1175 and promotes angiogenesis.\",\n      \"method\": \"miR-25-3p overexpression/inhibition, TULA-2 protein expression analysis, Syk and VEGFR-2 phosphorylation immunoblotting, co-immunoprecipitation, in vitro angiogenesis assay, in vivo hindlimb ischemia model\",\n      \"journal\": \"Aging\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP and phosphorylation analysis with functional in vitro/in vivo readouts, single lab\",\n      \"pmids\": [\"33201836\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"UBASH3B (Ubash3b) dephosphorylates PKCδ in leukemia cells treated with TPA, promoting PKCδ protein degradation via the proteasome; RNAi depletion of Ubash3b blocks TPA-induced PKCδ loss.\",\n      \"method\": \"RNAi knockdown, proteasome inhibitor treatment, PKCδ phosphorylation and protein level analysis, leukemia mouse model\",\n      \"journal\": \"Biochimie\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — RNAi KD with specific mechanistic readout (PKCδ phosphorylation/degradation), single lab\",\n      \"pmids\": [\"33556471\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"UBASH3B directly binds MRPL12 and dephosphorylates its tyrosine 60, which impedes MRPL12 binding to mitochondrial RNA polymerase POLRMT and downregulates mitochondrial oxidative phosphorylation, thereby inhibiting LUAD tumor progression.\",\n      \"method\": \"Mass spectrometry identification of phosphorylation site, co-immunoprecipitation (UBASH3B–MRPL12, MRPL12–POLRMT), Y60 phospho-mutant functional assays, in vitro/in vivo/organoid LUAD models\",\n      \"journal\": \"Journal of experimental & clinical cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — MS-defined site, Co-IP, phospho-mutant validation in multiple model systems, single lab\",\n      \"pmids\": [\"39343960\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"UBASH3B (Sts-1/TULA-2) is a multi-domain protein containing UBA, SH3, and histidine phosphatase (PGM-like) domains that functions as a negative regulator of receptor tyrosine kinase and immune receptor signaling: it dephosphorylates key tyrosine kinase substrates including Syk (at pY346/pY352/pY323), ZAP-70, and CBL using a histidine-based catalytic mechanism, recruits to ubiquitylated proteins via its UBA domain (including ubiquitylated Aurora B to direct its mitotic localization), and suppresses receptor endocytosis by interacting with Cbl via its SH3 domain, collectively dampening TCR, GPVI, FcγRIIA, CLEC-2, and EGFR signaling while also controlling mitotic fidelity through Aurora B relocalization to microtubules.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"UBASH3B (Sts-1/TULA-2) is a multi-domain tyrosine phosphatase of the histidine phosphatase superfamily that broadly attenuates receptor-proximal signaling by dephosphorylating activated tyrosine kinases and their substrates. Its PGM-like catalytic domain dephosphorylates Syk (at pY346, pY352, pY323, pY525/526) and ZAP-70 to negatively regulate TCR, GPVI, FcγRIIA, FcεRI, and CLEC-2 signaling, and knockout mice exhibit hyperresponsive T cells, hyperactive platelets with a prothrombotic phenotype, and increased osteoclast numbers with reduced bone volume [PMID:14738763, PMID:20585042, PMID:27609517, PMID:23149425]. UBASH3B also dephosphorylates CBL ubiquitin ligase, stabilizing EGFR at the cell surface and promoting invasion in triple-negative breast cancer, and dephosphorylates MRPL12 to regulate mitochondrial transcription and oxidative phosphorylation [PMID:23784775, PMID:39343960]. Beyond its phosphatase function, UBASH3B acts as a ubiquitin receptor through its UBA domain, binding ubiquitylated Aurora B kinase to direct its relocalization to mitotic microtubules and ensure chromosome segregation fidelity [PMID:26766443].\",\n  \"teleology\": [\n    {\n      \"year\": 2004,\n      \"claim\": \"The foundational question of whether UBASH3B participates in immune signaling was answered when Sts-1/Sts-2 double-knockout mice revealed hyperresponsive T cells with elevated ZAP-70 phosphorylation, establishing UBASH3B as a negative regulator of TCR signaling.\",\n      \"evidence\": \"Double-knockout mice with phosphorylation assays and cytokine measurement in T cells\",\n      \"pmids\": [\"14738763\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Individual Sts-1 versus Sts-2 contributions not fully separated\", \"Mechanism of ZAP-70 dephosphorylation not yet identified\", \"Whether phosphatase activity was direct was unknown\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"The domain architecture and non-immune functions were established when UBASH3B was shown to interact with Cbl via its SH3 domain and with mono-ubiquitin via its UBA domain, and to inhibit EGFR/PDGFR endocytosis, revealing a role in receptor trafficking beyond TCR signaling.\",\n      \"evidence\": \"Reciprocal co-immunoprecipitation with domain-deletion constructs, receptor internalization assays\",\n      \"pmids\": [\"15159412\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether the effect on endocytosis was phosphatase-dependent was unknown\", \"In vivo relevance of receptor trafficking regulation not tested\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"A critical mechanistic question — whether UBASH3B acts as a phosphatase or an adaptor — was resolved by crystal structure determination and in vitro reconstitution showing intrinsic phosphatase activity through a histidine-based PGM-like catalytic domain, with active-site mutations impairing both enzymatic activity and TCR signaling regulation.\",\n      \"evidence\": \"X-ray crystallography, in vitro phosphatase assays, active-site mutagenesis with T cell signaling readouts\",\n      \"pmids\": [\"17679096\", \"17348005\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological substrates beyond ZAP-70 not yet defined\", \"Substrate specificity determinants unknown\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"UBASH3B's role was extended beyond T cells when it was shown to associate with and dephosphorylate Syk in platelets, negatively regulating GPVI signaling, and systematic peptide library screening defined two substrate-specificity classes and identified Syk pY323 and pY352 as preferred target sites.\",\n      \"evidence\": \"TULA-2 KO mouse platelet assays, in vitro dephosphorylation, combinatorial phosphopeptide library screening with kinetic analysis\",\n      \"pmids\": [\"20585042\", \"20670933\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Which Syk phosphosite is the primary regulatory target in vivo was unresolved\", \"Role in other ITAM/hemITAM receptor pathways not yet tested\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"The range of immune receptors regulated by UBASH3B expanded further with demonstration that it is recruited to phosphorylated Syk C-terminal tyrosines in mast cells after FcεRI activation and suppresses degranulation and NF-κB/NFAT activation, while in bone it was shown to regulate osteoclastogenesis through Syk dephosphorylation at Y352 and Y525/526.\",\n      \"evidence\": \"Phosphopeptide pulldown with MS, siRNA knockdown in mast cells; DKO mouse skeletal analysis with phosphatase-dead mutant in osteoclasts\",\n      \"pmids\": [\"22267732\", \"23149425\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How UBASH3B is recruited to distinct receptor complexes remained unclear\", \"Relative importance of different Syk phosphosites across cell types unresolved\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"A direct phosphatase–substrate relationship was validated when substrate-trapping mutants (H380A, E490A) retained high-affinity binding to phospho-ZAP-70, and UBASH3B was shown to dephosphorylate CBL, inactivating its E3 ligase function and upregulating EGFR to promote breast cancer invasion and metastasis.\",\n      \"evidence\": \"Active-site substrate-trapping mutagenesis in T cells; siRNA/phosphatase-dead mutant rescue in TNBC cells with xenograft model\",\n      \"pmids\": [\"24256567\", \"23784775\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Full catalogue of UBASH3B substrates beyond ZAP-70, Syk, and CBL unknown\", \"Whether CBL dephosphorylation occurs in normal physiology not addressed\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"The primary regulatory mechanism in platelets was pinpointed to dephosphorylation of Syk pY346, and UBASH3B's role was extended to FcγRIIA signaling where its loss worsened heparin-induced thrombocytopenia; concurrently, a non-phosphatase function was discovered in which UBASH3B's UBA domain binds ubiquitylated Aurora B to control its mitotic localization and chromosome segregation fidelity.\",\n      \"evidence\": \"In vitro kinetics with site-specific phosphopeptides and KO platelet analysis; FcγRIIA-transgenic/TULA-2-KO mice with in vivo HIT model; Co-IP of ubiquitylated Aurora B, live-cell imaging, LOF/GOF mitotic assays\",\n      \"pmids\": [\"27609517\", \"27765766\", \"26766443\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether the UBA-mediated mitotic function requires phosphatase activity is unknown\", \"Structural basis of Aurora B ubiquitin recognition not determined\", \"Clinical relevance of UBASH3B in thrombotic disease not established\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"High-resolution crystal structures of the Sts-1 and Sts-2 histidine phosphatase domains explained the ~100-fold activity difference between paralogs and identified PHPS1 as a micromolar inhibitor, providing a structural framework for selective targeting.\",\n      \"evidence\": \"X-ray crystallography at 1.9–2.5 Å resolution, steady-state kinetics, inhibitor Ki determination\",\n      \"pmids\": [\"28759203\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No co-crystal with a phosphotyrosine substrate exists\", \"Selectivity of PHPS1 for UBASH3B over other histidine phosphatases not fully profiled\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"UBASH3B's role as a universal negative regulator of Syk-dependent signaling was consolidated when CLEC-2/hemITAM pathway activation was shown to be enhanced in TULA-2 KO platelets through failure to dephosphorylate Syk Y346.\",\n      \"evidence\": \"TULA-2 KO mouse platelets stimulated with CLEC-2 agonist, site-specific phosphorylation and functional aggregation assays\",\n      \"pmids\": [\"31249969\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether UBASH3B regulation of CLEC-2 signaling is relevant in lymphatic development not tested\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"UBASH3B function was extended to endothelial biology when miR-25-3p–mediated suppression of TULA-2 was shown to increase Syk pY323 and VEGFR-2 pY1175 phosphorylation, promoting angiogenesis in vitro and in vivo.\",\n      \"evidence\": \"miR-25-3p overexpression/inhibition, Co-IP of TULA-2–Syk, VEGFR-2 phosphorylation analysis, hindlimb ischemia model\",\n      \"pmids\": [\"33201836\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct dephosphorylation of VEGFR-2 by UBASH3B not demonstrated\", \"Single-lab observation\", \"Endogenous miR-25-3p regulation of UBASH3B in disease contexts not validated\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"The substrate repertoire was further broadened when UBASH3B was found to dephosphorylate PKCδ, promoting its proteasomal degradation in leukemia cells treated with TPA.\",\n      \"evidence\": \"RNAi knockdown with proteasome inhibitor treatment, PKCδ phosphorylation and stability analysis\",\n      \"pmids\": [\"33556471\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Specific PKCδ phosphosite targeted by UBASH3B not identified\", \"Not independently replicated\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"A mitochondrial function was uncovered when UBASH3B was shown to directly bind and dephosphorylate MRPL12 at Y60, disrupting the MRPL12–POLRMT interaction and downregulating mitochondrial oxidative phosphorylation to suppress lung adenocarcinoma progression.\",\n      \"evidence\": \"MS-identified phosphosite, Co-IP, Y60 phosphomutant studies in LUAD cell lines, xenografts, and organoids\",\n      \"pmids\": [\"39343960\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether UBASH3B enters mitochondria or acts before import is unclear\", \"Single-lab finding awaiting replication\", \"In vivo relevance in normal mitochondrial physiology not tested\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include how UBASH3B's phosphatase and ubiquitin-binding functions are coordinated, what determines substrate selectivity across diverse receptor systems, and whether UBASH3B can be therapeutically targeted to modulate thrombosis or anti-tumor immunity.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No co-crystal structure with a physiological phosphotyrosine substrate\", \"Integration of UBA-mediated and phosphatase-mediated functions not mechanistically resolved\", \"No selective high-potency inhibitor or activator reported\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [2, 4, 5, 6, 7, 8, 9, 13, 14, 15, 17, 19, 20]},\n      {\"term_id\": \"GO:0016787\", \"supporting_discovery_ids\": [2, 3, 5, 15]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [1, 9]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [12]},\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [20]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [0, 6, 9, 14, 17]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [1, 8, 18, 20]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [12]},\n      {\"term_id\": \"R-HSA-109582\", \"supporting_discovery_ids\": [4, 13, 14]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [20]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"SYK\",\n      \"ZAP70\",\n      \"CBL\",\n      \"AURKB\",\n      \"MRPL12\",\n      \"SHC1\",\n      \"EGFR\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}