{"gene":"C1GALT1","run_date":"2026-06-09T22:02:45","timeline":{"discoveries":[{"year":2022,"finding":"X-ray crystallography of C1GalT1 complexed to a glycopeptide revealed that C1GalT1 is an obligate GT-A fold dimer that follows an SN2 inverting mechanism. Substrate binding is primarily driven by the GalNAc moiety while the peptide sequence provides optimal kinetic and binding parameters. C1GalT1 recognizes a high-energy conformation of the α-GalNAc-Thr linkage (normally negligibly populated in solution), and by imposing this 3D arrangement—characteristic of α-GalNAc-Ser peptides—it ensures broad glycosylation of both Ser and Thr acceptor substrates.","method":"X-ray crystallography of enzyme–glycopeptide complex, biophysical assays, cellular studies, site-directed mechanistic analysis","journal":"Nature Communications","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure with functional validation plus biophysical and cellular orthogonal methods in a single rigorous study","pmids":["35504880"],"is_preprint":false},{"year":2009,"finding":"The ER-localized molecular chaperone Cosmc directly interacts with partly denatured (non-native) T-synthase in vitro to cause partial restoration of T-synthase activity, in an ATP-independent fashion. A mutated Cosmc found in Tn-syndrome patients has reduced chaperone function. Cosmc is specific for T-synthase and does not act on another β-galactosyltransferase tested, representing the first ER chaperone identified for folding of a glycosyltransferase.","method":"In vitro chaperone refolding assay, mutagenesis of patient-derived Cosmc variant, activity assay","journal":"The Journal of Biological Chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution with mutagenesis, replicated across multiple papers from same lab with orthogonal methods","pmids":["19923218"],"is_preprint":false},{"year":2012,"finding":"Cosmc binds specifically to non-native (denatured) T-synthase but not to the active dimeric form. The Cosmc–T-synthase complex is relatively stable, forms in an ATP-independent manner not regulated by redox, calcium, pH, or intermolecular disulfide bonds, and leads to partial reactivation of T-synthase. Active T-synthase remains tightly noncovalently bound to Cosmc; dissociation is promoted in a client-driven process by further interactions with free native or non-native T-synthase.","method":"In vitro binding assays using recombinant proteins (free and solid-support-immobilized Cosmc), activity measurements, biochemical characterization","journal":"The Journal of Biological Chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution with multiple orthogonal biochemical methods; mechanistic model confirmed in same study","pmids":["22416136"],"is_preprint":false},{"year":2014,"finding":"A specific linear, relatively hydrophobic peptide motif (CBRT) in the N-terminal stem region of T-synthase is required for binding to Cosmc. A synthetic CBRT peptide directly binds Cosmc and inhibits Cosmc-assisted refolding of denatured T-synthase. Mutations within CBRT diminish Cosmc binding and result in formation of inactive T-synthase. Inserting the T-synthase stem region into the unrelated β4GalT1 confers Cosmc binding on that chimera, confirming CBRT as a sequence-specific chaperone recognition motif.","method":"Deletion mutagenesis, synthetic peptide binding assay, in vitro refolding assay, domain-swap chimera experiment","journal":"The Journal of Biological Chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — mutagenesis plus in vitro assays plus domain-swap validation, multiple orthogonal methods in one study","pmids":["24616093"],"is_preprint":false},{"year":2007,"finding":"Immunocytochemical analysis demonstrated that C1GalT (T-synthase) is localized in the Golgi apparatus, while its chaperone Cosmc resides in the endoplasmic reticulum. In cells with a Cosmc loss-of-function missense mutation (LSC cells), C1GalT protein is absent; proteasome inhibition restores C1GalT protein but it fails to reach the Golgi. Overexpression of Cosmc (but not C1GalT itself) restores correct Golgi localization of C1GalT and recovers core 1 synthase activity, demonstrating that Cosmc controls intracellular trafficking and active localization of C1GalT.","method":"Immunocytochemistry with specific monoclonal antibodies, proteasome inhibitor treatment, overexpression rescue, activity assay","journal":"Biochemical and Biophysical Research Communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct localization experiments with functional consequence (activity rescue), multiple orthogonal approaches","pmids":["18061573"],"is_preprint":false},{"year":2006,"finding":"Targeted disruption of the T-synthase gene (C1galt1) in mice causes embryonic lethality by E14 due to defective angiogenesis: T-synthase-null embryos express unsialylated Tn antigen instead of sialyl-T antigen in endothelial, hematopoietic, and epithelial cells and develop brain hemorrhage with chaotic microvascular networks, distorted capillary lumens, and defective pericyte–endothelial cell–ECM associations, revealing an essential requirement for core 1-derived O-glycans in angiogenesis.","method":"Gene targeting (knockout mice), immunostaining, vascular morphology analysis","journal":"Methods in Enzymology","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knockout with defined developmental phenotype and mechanistic cellular readout","pmids":["17113876"],"is_preprint":false},{"year":2006,"finding":"A hypomorphic loss-of-function point mutation in C1galt1 in plt1 mice causes recessive thrombocytopenia and kidney disease. GPIbα in platelets and podocalyxin in kidney were identified as major underglycosylated targets of C1GalT1, indicating that proper O-glycosylation of these substrates is essential for platelet production and kidney function. Thrombocytopenia was not rescued on a lymphocyte-deficient background, indicating an intrinsic (non-immune-mediated) defect in megakaryocytes.","method":"ENU mutagenesis screen, genetic mapping, biochemical identification of underglycosylated substrates (GPIbα, podocalyxin), rag1-null epistasis","journal":"Proceedings of the National Academy of Sciences","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo loss-of-function with substrate identification and epistasis experiment, multiple orthogonal approaches","pmids":["17062753"],"is_preprint":false},{"year":2013,"finding":"Conditional ablation of C1galt1 in hematopoietic cells (Mx1-Cre) causes severe thrombocytopenia with giant platelets and prolonged bleeding times due to defective proplatelet formation during terminal megakaryocyte differentiation. GPIbα protein (but not mRNA) is significantly reduced in C1galt1-null megakaryocytes and platelets, suggesting increased proteolysis of under-O-glycosylated GPIbα. Circulating null platelets show increased microtubule coils despite normal tubulin levels.","method":"Conditional knockout (Mx1-Cre), bone marrow transplantation, flow cytometry, western blot, primary megakaryocyte culture","journal":"Blood","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional KO with multiple orthogonal methods and substrate-level mechanistic follow-up","pmids":["23794065"],"is_preprint":false},{"year":2013,"finding":"C1GALT1 modifies O-glycans on the MET receptor tyrosine kinase in hepatocellular carcinoma cells (demonstrated by VVA and PNA lectin binding), enhancing HGF-induced MET dimerization and kinase activation. C1GALT1 overexpression enhanced HGF-induced MET phosphorylation and cell proliferation; C1GALT1 silencing suppressed MET phosphorylation and proliferation in vitro and in vivo. MET blockade abrogated C1GALT1-enhanced cell viability.","method":"RNAi knockdown and overexpression, lectin pull-down (VVA/PNA), phosphorylation assays, MET inhibitor epistasis, xenograft model","journal":"Cancer Research","confidence":"High","confidence_rationale":"Tier 2 / Strong — substrate identification by lectin pulldown plus functional epistasis with inhibitor and in vivo validation, multiple orthogonal methods","pmids":["23832667"],"is_preprint":false},{"year":2014,"finding":"C1GALT1 modifies O-glycans on FGFR2 in colon cancer cells (first demonstration that FGFR2 carries O-glycans) and enhances bFGF-triggered FGFR2 phosphorylation and downstream malignant phenotypes. FGFR inhibitor BGJ398 blocked C1GALT1-enhanced effects, placing C1GALT1 upstream of FGFR2 activation.","method":"Lectin blotting, RNAi knockdown and overexpression, FGFR inhibitor epistasis, in vitro and xenograft assays","journal":"Oncotarget","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — substrate identification by lectin blotting plus pharmacological epistasis, single lab, two orthogonal approaches","pmids":["24758762"],"is_preprint":false},{"year":2014,"finding":"C1GALT1 modifies O-glycans on integrin β1 in hepatocellular carcinoma cells and regulates integrin β1 activity and downstream signaling, thereby promoting cell adhesion to ECM, migration, and invasion. Anti-integrin β1 blocking antibody significantly suppressed C1GALT1-enhanced phenotypes, placing C1GALT1 upstream of integrin β1 activity.","method":"Lectin pull-down, RNAi knockdown and overexpression, integrin β1 blocking antibody epistasis, xenograft model","journal":"PLoS One","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — lectin-based substrate identification plus antibody epistasis, single lab, two orthogonal approaches","pmids":["25089569"],"is_preprint":false},{"year":2015,"finding":"C1GALT1 modulates O-glycan structures on MUC1 in breast cancer cells and promotes MUC1-C/β-catenin signaling pathway activation, enhancing cell growth, migration, and invasion in vitro and tumor growth in vivo.","method":"Lectin blotting, RNAi knockdown and overexpression, pathway activation assays, xenograft model","journal":"Oncotarget","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — lectin-based substrate identification plus functional pathway assays, single lab","pmids":["25762620"],"is_preprint":false},{"year":2018,"finding":"C1GALT1 modifies O-glycan structures on integrin β1 (β1-integrin) in esophageal cancer cells and regulates downstream FAK signaling. C1GALT1 knockdown increased radiosensitivity; β1-integrin blocking antibody and FAK inhibitor enhanced radiation-induced apoptosis, placing C1GALT1–β1-integrin–FAK in a radioresistance pathway.","method":"Lectin blotting, RNAi knockdown, integrin blocking antibody and FAK inhibitor epistasis, irradiation assays","journal":"Journal of Cancer","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — substrate identification by lectin blotting plus pharmacological epistasis, single lab","pmids":["30087707"],"is_preprint":false},{"year":2018,"finding":"Disruption of C1galt1 in the KPC mouse pancreatic cancer model (KPCC mice) significantly accelerated PDAC development and metastasis. In human PDAC cells, C1GALT1 knockout via CRISPR/Cas9 caused aberrant glycosylation of MUC16 (identified by lectin pull-down and mass spectrometry) and upregulation of genes regulating tumorigenesis and metastasis.","method":"Conditional knockout in KPC mice (genetic epistasis), CRISPR/Cas9 KO, lectin pull-down, mass spectrometry, RNA sequencing, orthotopic model","journal":"Gastroenterology","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo genetic model plus CRISPR KO with substrate identification by MS and transcriptomic analysis, multiple orthogonal methods","pmids":["30086262"],"is_preprint":false},{"year":2021,"finding":"C1GALT1 modifies O-glycosylation on integrin α5 in gastric cancer cells (identified by lectin pull-down and mass spectrometry) and modulates activation of the PI3K/AKT pathway. Integrin α5 inhibition reversed C1GALT1-mediated tumor growth and metastasis in vitro and in vivo. Transcription factor SP1 was found to bind the C1GALT1 promoter and activate its expression, while miR-152 negatively regulates C1GALT1 by binding its 3′-UTR.","method":"Lectin pull-down, mass spectrometry, RNAi and overexpression, PI3K/AKT pathway assays, in vivo xenograft, ChIP/promoter binding, luciferase reporter","journal":"Cell & Bioscience","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — substrate identified by MS plus pathway epistasis, single lab, orthogonal methods","pmids":["34452648"],"is_preprint":false},{"year":2025,"finding":"C1GALT1 O-glycosylates the Hedgehog signaling component Smoothened (SMO), thereby stabilizing SMO and stimulating Hedgehog pathway activity, which directly activates EWSR1::FLI1 transcription in Ewing sarcoma cells. C1GALT1 was identified as required for EWSR1::FLI1 expression by genome-scale CRISPR/Cas9 knockout screening, and its pharmacological inhibition (itraconazole) reduced EWSR1::FLI1 levels and suppressed ES xenograft growth.","method":"Genome-scale CRISPR/Cas9 KO screen, O-glycosylation assays, Hedgehog pathway assays, xenograft model, itraconazole pharmacological inhibition","journal":"Nature Communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — unbiased CRISPR screen plus substrate (SMO) glycosylation assays plus pathway epistasis plus in vivo pharmacological validation, multiple orthogonal methods","pmids":["39894896"],"is_preprint":false},{"year":2008,"finding":"Systematic peptide substrate profiling using oriented random glycopeptides revealed that T-synthase prefers Gly at the +1 position and Phe/Tyr at the +3 position relative to the acceptor Thr-O-GalNAc. Basic residues (Lys, Arg, His) in any position are disfavored, suggesting electrostatic interactions modulate transferase specificity.","method":"Oriented random glycopeptide library, PNA lectin affinity isolation, Edman amino acid sequencing, in vitro enzyme assay","journal":"Glycobiology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro enzyme assay with systematic substrate library, rigorous quantitative analysis, single lab","pmids":["19073881"],"is_preprint":false},{"year":2006,"finding":"The C. elegans ortholog Ce-T-synthase (encoded by C38H2.2, 42.7% identity to human T-synthase) was cloned and shown to be a functional ortholog: it catalyzes addition of Gal to GalNAc-Ser/Thr to form core 1 O-glycans. Unlike vertebrate T-synthase, Ce-T-synthase does not require the Cosmc chaperone and instead requires invertebrate-specific factors for optimal activity.","method":"cDNA cloning, recombinant expression in mammalian and insect cells, enzyme activity assay, promoter-GFP analysis","journal":"Glycobiology","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — in vitro enzymatic characterization of ortholog with Cosmc-independence established experimentally, single lab","pmids":["16762980"],"is_preprint":false},{"year":2015,"finding":"The human C1GALT1 (T-synthase) promoter lacks a TATA box but contains a CpG island (tCpG) whose core promoter contains two binding sites for SP1/SP3 (Krüppel-like transcription factors). SP1/SP3 binding drives basal transcription of C1GALT1, as demonstrated by luciferase reporter assays, site-directed mutagenesis of binding sites, ChIP assays, and mithramycin A treatment. Unlike Cosmc, the T-synthase promoter CpG island is not hypermethylated in Tn-syndrome B cells, indicating differential epigenetic regulation.","method":"Luciferase reporter assay, site-directed mutagenesis, ChIP assay, mithramycin A treatment, methylome analysis","journal":"The Journal of Biological Chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (reporter, mutagenesis, ChIP, methylome) establishing transcriptional mechanism in a single study","pmids":["26063800"],"is_preprint":false},{"year":2014,"finding":"IL-6 and IL-4 cytokines reduce IgA1 galactosylation directly by decreasing C1GalT1 expression and indirectly by increasing ST6GalNAc-II expression (which sialylates the GalNAc substrate, preventing C1GalT1-mediated galactosylation). These findings were confirmed by siRNA knockdown of C1GALT1 and ST6GalNAc-II genes and by in vitro enzyme reactions.","method":"siRNA knockdown, cytokine treatment of IgA1-secreting cells, in vitro enzyme reactions, O-glycan analysis","journal":"The Journal of Biological Chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — siRNA plus in vitro enzyme reactions plus glycan analysis, multiple orthogonal methods confirming mechanism","pmids":["24398680"],"is_preprint":false},{"year":2012,"finding":"Knockdown of C1galt1 (T-synthase) in corneal keratinocytes increased endocytic uptake of plasma membrane proteins via clathrin-mediated endocytosis (blocked by dynasore, nocodazole, chlorpromazine, and hyperosmotic sucrose), demonstrating that core 1 O-glycans contribute to apical barrier function by preventing clathrin-coated pit-mediated endocytosis.","method":"Tetracycline-inducible RNAi, cell surface biotinylation, subcellular fractionation, confocal microscopy, fluorescent nanosphere uptake, pharmacological inhibitors","journal":"PLoS One","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization/trafficking experiment with functional consequence and pharmacological epistasis, single lab, multiple methods","pmids":["22574202"],"is_preprint":false},{"year":2018,"finding":"CRISPR/Cas9 knockout of T-synthase (C1GALT1) in colorectal cancer HCT116 cells induced Tn antigen expression and enhanced proliferation, adhesion, migration, and invasion. T-synthase deficiency directly induced epithelial-to-mesenchymal transition (EMT) with decreased E-cadherin and increased snail and fibronectin expression.","method":"CRISPR/Cas9 KO, flow cytometry, western blot, invasion/migration assays, EMT marker analysis","journal":"BioMed Research International","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — CRISPR KO with defined EMT phenotypic readout, single lab","pmids":["30035127"],"is_preprint":false},{"year":2023,"finding":"The UDP-galactose transporter SLC35A2 (UGT) physically associates with C1GalT1 (T-synthase) in HEK293T cells. SLC35A2 also associates with Cosmc. In SLC35A2-deficient cells, C1GalT1 and Cosmc protein levels are decreased, their Golgi localization is less pronounced, and O-glycosylation is reduced. Endogenous Cosmc was found to localize in both the ER and Golgi apparatus of wild-type cells.","method":"Co-immunoprecipitation, western blot, immunofluorescence microscopy, SLC35A2 KO cells, subcellular fractionation","journal":"Biochimica et Biophysica Acta – Molecular Cell Research","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — Co-IP plus localization with KO consequence, single lab, multiple orthogonal methods","pmids":["36933771"],"is_preprint":false},{"year":2020,"finding":"miR-124-3p directly targets T-synthase (C1GALT1) mRNA, reducing T-synthase protein expression in aged colon, disrupting O-glycosylation of mucins, compromising the colonic mucus barrier, and increasing susceptibility to colitis. Young mice overexpressing miR-124-3p phenocopied aged-colon glycosylation defects and developed more severe colitis.","method":"miRNA target validation, miR-124-3p overexpression in vivo, western blot, O-glycan analysis, colitis scoring","journal":"Aging Cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct miRNA targeting experiment with in vivo phenotypic readout, single lab","pmids":["33040455"],"is_preprint":false},{"year":2024,"finding":"C1GalT1 undergoes O-GlcNAc modification at Thr229 and Thr233. This O-GlcNAcylation stabilizes C1GalT1 protein and strengthens its interaction with Cosmc. Mutation at these residues attenuates C1GalT1 stability and promotes its degradation via the proteasome pathway.","method":"O-GlcNAc modification identification, site-directed mutagenesis (Thr229/Thr233), Co-IP with Cosmc, proteasome inhibitor treatment, western blot","journal":"Acta Biochimica et Biophysica Sinica","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — PTM identification with mutagenesis plus interaction assays, single lab, two orthogonal methods","pmids":["39126245"],"is_preprint":false},{"year":2024,"finding":"C1GALT1 knockdown decreased terminal galactose O-glycosylation and phosphorylation of EGFR in glioblastoma cells, attenuated downstream AKT/ERK phosphorylation, and reduced expression of cyclin D1 and MMP9. Transcription factor SP1 was found to bind the C1GALT1 promoter and regulate its expression in glioma.","method":"siRNA knockdown, O-glycan analysis, EGFR and AKT/ERK phosphorylation assays, xenograft model, SP1 promoter binding analysis","journal":"Cellular Signalling","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — substrate glycosylation and downstream pathway assays with KD and in vivo validation, single lab","pmids":["39561885"],"is_preprint":false},{"year":2012,"finding":"T-synthase knockdown via shRNA induced galectin-1 secretion both in vitro and in vivo, enhanced Th2 cytokine (IL-10 and IL-4) production, and promoted CD8+ T-cell apoptosis through galectin-1, prolonging skin allograft survival in mice. This places C1GALT1 upstream of galectin-1-mediated immune suppression.","method":"shRNA knockdown in CT26 cells and in vivo (intramuscular electroporation), ELISA for cytokines/galectin-1, apoptosis assays, skin allograft survival model","journal":"Journal of Clinical Immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo KD with defined immune phenotype and mechanistic pathway placement via galectin-1, single lab","pmids":["22392045"],"is_preprint":false},{"year":2026,"finding":"In vivo experiment using B cell-specific C1galt1 knockout in a human IGHA1 knock-in mouse demonstrated that loss of C1galt1 in B cells markedly elevated circulating Gd-IgA1 under physiological and inflammatory conditions but did not substantially enhance glomerular IgA deposition, indicating that galactose-deficient IgA1 per se is not sufficient to drive glomerular deposition. In a passive transfer model, mucosal-origin IgA1 induced stronger mesangial deposition than serum or myeloma IgA1 despite similar or lower Gd-IgA1 content.","method":"B cell-specific conditional knockout, passive transfer model, ELISA for Gd-IgA1, kidney histology, flow cytometry","journal":"Kidney International","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo conditional KO with defined molecular and histological readouts, single study","pmids":["41905596"],"is_preprint":false},{"year":2026,"finding":"Inhibition of NF-κB/p65 by a selective IKKβ inhibitor (TPCA-1) in EBV-immortalized IgA1-producing B cells reduced C1GALT1 gene expression and increased Gd-IgA1 production. Co-localization of NF-κB/p65 with transcription factor SP1 was altered in nuclei, suggesting the NF-κB pathway regulates IgA1 O-glycosylation via SP1-mediated transcriptional control of C1GALT1.","method":"IKKβ inhibitor treatment, flow cytometry, imaging, gene expression analysis, nuclear translocation assay","journal":"bioRxiv","confidence":"Low","confidence_rationale":"Tier 3 / Weak — pharmacological inhibitor with correlative SP1 co-localization, single lab, preprint, no direct ChIP or mutagenesis confirming SP1–C1GALT1 link","pmids":["42146603"],"is_preprint":true}],"current_model":"C1GALT1 (T-synthase) is an obligate GT-A fold dimeric inverting glycosyltransferase that resides in the Golgi apparatus and catalyzes transfer of galactose from UDP-Gal to GalNAc-Ser/Thr to form the core 1 O-glycan (Galβ1-3GalNAcα-Ser/Thr), a process essential for angiogenesis, megakaryocyte differentiation, and epithelial barrier integrity; its activity depends on prior folding by the ER-specific chaperone Cosmc, which binds a hydrophobic stem-region motif (CBRT) in non-native T-synthase, restores activity in an ATP-independent client-driven cycle, and enables correct Golgi trafficking; C1GALT1 is transcriptionally driven by SP1/SP3 binding to a CpG-island core promoter and is post-translationally stabilized by O-GlcNAcylation at Thr229/Thr233; in cancer contexts it O-glycosylates multiple receptor substrates including MET, FGFR2, integrin β1, integrin α5, MUC1, MUC16, Smoothened, and EGFR, modifying their dimerization, activation, and downstream signaling (HGF/MET, bFGF/FGFR2, integrin/FAK, PI3K/AKT, Hedgehog/EWSR1::FLI1, AKT/ERK) to broadly promote or suppress cancer progression in a context-dependent manner."},"narrative":{"mechanistic_narrative":"C1GALT1 (T-synthase) is a Golgi-resident inverting glycosyltransferase that catalyzes the committed step of mucin-type O-glycan extension, transferring galactose from UDP-Gal onto GalNAc-Ser/Thr to form the core 1 structure (Galβ1-3GalNAcα-Ser/Thr) [PMID:35504880, PMID:18061573]. Crystallographic and biophysical analysis shows it functions as an obligate GT-A fold dimer using an SN2 inverting mechanism, with substrate recognition driven primarily by the GalNAc moiety; the enzyme imposes a high-energy conformation on the α-GalNAc-Thr linkage to glycosylate both Ser and Thr acceptors, with peptide context (Gly at +1, Phe/Tyr at +3) tuning specificity [PMID:35504880, PMID:19073881]. Maturation of vertebrate T-synthase requires the ER-specific chaperone Cosmc, which binds a hydrophobic stem-region motif (CBRT) only in non-native enzyme, restores activity in an ATP-independent client-driven cycle, and is required for productive Golgi trafficking and active localization [PMID:19923218, PMID:22416136, PMID:24616093, PMID:18061573]. The enzyme is transcriptionally driven by SP1/SP3 acting on a CpG-island core promoter [PMID:26063800] and is post-translationally stabilized by O-GlcNAcylation at Thr229/Thr233, which also reinforces the Cosmc interaction and protects against proteasomal degradation [PMID:39126245]. Core 1 O-glycans generated by C1GALT1 are essential in vivo: genetic loss causes embryonic-lethal angiogenic failure [PMID:17113876] and, in hematopoietic and renal cells, underglycosylation of substrates such as GPIbα and podocalyxin producing thrombocytopenia and kidney disease [PMID:17062753, PMID:23794065]. In cancer the enzyme O-glycosylates numerous cell-surface receptors—MET, FGFR2, integrins β1 and α5, MUC1, MUC16, Smoothened and EGFR—to modulate their stability, dimerization, activation and downstream signaling (HGF/MET, bFGF/FGFR2, integrin/FAK, PI3K/AKT, Hedgehog, AKT/ERK), driving context-dependent tumor progression or, in pancreatic cancer, tumor suppression [PMID:23832667, PMID:24758762, PMID:30086262, PMID:34452648, PMID:39894896, PMID:39561885]. Reduced C1GALT1 activity also underlies galactose-deficient IgA1 production relevant to IgA nephropathy [PMID:24398680, PMID:41905596].","teleology":[{"year":2006,"claim":"Establishing that core 1 O-glycans are physiologically essential, not merely structural decoration, anchored the enzyme's biological importance.","evidence":"Gene targeting and ENU hypomorphic mutation in mice with vascular and hematopoietic/renal phenotypes","pmids":["17113876","17062753"],"confidence":"High","gaps":["Did not define the molecular catalytic mechanism","Substrate scope beyond GPIbα/podocalyxin not resolved in these studies"]},{"year":2007,"claim":"Defining the spatial logic—ER chaperone versus Golgi enzyme—showed that the enzyme's activity is gated by trafficking, not just expression.","evidence":"Immunocytochemistry, proteasome inhibition, and Cosmc overexpression rescue in mutant cells","pmids":["18061573"],"confidence":"High","gaps":["Molecular basis of Cosmc recognition not yet identified","Did not address trafficking machinery beyond Cosmc"]},{"year":2009,"claim":"Direct in vitro reconstitution proved Cosmc is a bona fide folding chaperone specific for T-synthase, explaining Tn-syndrome at the protein-folding level.","evidence":"In vitro chaperone refolding assays with patient-derived Cosmc mutant and activity measurements","pmids":["19923218"],"confidence":"High","gaps":["Recognition motif on T-synthase not yet mapped","Mechanism of client release undefined at this stage"]},{"year":2012,"claim":"Characterizing the binding/release cycle established that Cosmc operates ATP-independently in a client-driven manner, distinguishing it from canonical chaperones.","evidence":"In vitro binding and activity assays with recombinant immobilized Cosmc and free/non-native T-synthase","pmids":["22416136"],"confidence":"High","gaps":["Structural basis of the complex not resolved","In-cell kinetics of the cycle not measured"]},{"year":2014,"claim":"Mapping the CBRT stem-region motif and validating it by domain swap defined the sequence determinant of chaperone specificity.","evidence":"Deletion mutagenesis, synthetic peptide binding/inhibition, and β4GalT1 chimera transfer","pmids":["24616093"],"confidence":"High","gaps":["Structure of the CBRT–Cosmc interface unresolved","How CBRT recognition discriminates native vs non-native states not detailed"]},{"year":2008,"claim":"Systematic acceptor-peptide profiling defined the sequence context that tunes T-synthase specificity beyond the GalNAc anchor.","evidence":"Oriented random glycopeptide library with PNA affinity isolation, Edman sequencing, and in vitro enzyme assay","pmids":["19073881"],"confidence":"High","gaps":["Structural rationale for +1/+3 preferences provided only later","Does not address in-cell substrate selection"]},{"year":2022,"claim":"The crystal structure unified prior biochemistry by revealing an obligate GT-A dimer, SN2 inverting catalysis, and the conformational trick allowing dual Ser/Thr glycosylation.","evidence":"X-ray crystallography of enzyme–glycopeptide complex with biophysical and cellular validation","pmids":["35504880"],"confidence":"High","gaps":["Does not capture the Cosmc-bound non-native state","In-cell conformational dynamics not addressed"]},{"year":2015,"claim":"Identifying SP1/SP3 at a CpG-island core promoter defined the basal transcriptional control distinct from Cosmc's epigenetic regulation.","evidence":"Luciferase reporter, site-directed mutagenesis, ChIP, mithramycin A treatment, methylome analysis","pmids":["26063800"],"confidence":"High","gaps":["Upstream signals controlling SP1/SP3 at this promoter not defined here","Tissue-specific regulation not addressed"]},{"year":2024,"claim":"Discovery of O-GlcNAcylation at Thr229/Thr233 established a post-translational layer that stabilizes the enzyme and reinforces Cosmc binding.","evidence":"O-GlcNAc mapping, site-directed mutagenesis, Co-IP with Cosmc, proteasome inhibition","pmids":["39126245"],"confidence":"Medium","gaps":["Enzymes adding/removing this modification not identified","Single-lab finding without structural confirmation"]},{"year":2023,"claim":"Linking the enzyme to the UDP-galactose transporter SLC35A2 connected nucleotide-sugar supply to enzyme stability and Golgi localization.","evidence":"Co-immunoprecipitation, immunofluorescence, and SLC35A2-KO cell analysis","pmids":["36933771"],"confidence":"Medium","gaps":["Co-IP without reciprocal/structural validation of the interaction","Whether association is direct or complex-mediated unresolved"]},{"year":2013,"claim":"Identifying receptor substrates (MET, GPIbα) showed that core 1 glycosylation directly modulates receptor activation and protein stability, extending the enzyme into signaling and platelet biology.","evidence":"Lectin pull-down, RNAi/overexpression, phosphorylation and inhibitor epistasis, conditional KO, xenograft","pmids":["23832667","23794065"],"confidence":"High","gaps":["Specific O-glycan sites on receptors not mapped","Generalizability across receptor classes not yet tested"]},{"year":2021,"claim":"A series of cancer studies established a recurring theme: C1GALT1 glycosylates surface receptors (FGFR2, integrins β1/α5, MUC1/MUC16) to tune adhesion and growth-factor signaling, with context-dependent pro- or anti-tumor outcomes.","evidence":"Lectin pull-down/MS substrate identification, pathway and inhibitor epistasis, CRISPR KO, in vivo models","pmids":["24758762","25089569","25762620","30087707","30086262","34452648"],"confidence":"Medium","gaps":["Most substrate identifications rely on lectin-based assays from single labs","Determinants of pro- vs anti-tumor outcome not mechanistically resolved"]},{"year":2025,"claim":"An unbiased CRISPR screen placed C1GALT1 upstream of an oncogenic fusion by showing it glycosylates and stabilizes Smoothened to drive Hedgehog-dependent EWSR1::FLI1 expression, nominating it as a druggable dependency.","evidence":"Genome-scale CRISPR KO screen, SMO O-glycosylation assays, Hedgehog pathway epistasis, itraconazole, xenograft","pmids":["39894896"],"confidence":"High","gaps":["SMO O-glycan sites not defined","Specificity of itraconazole for the C1GALT1 axis not fully isolated"]},{"year":2026,"claim":"B cell-specific knockout in a humanized IgA1 model refined the role in IgA nephropathy, showing galactose-deficient IgA1 alone is insufficient for glomerular deposition.","evidence":"B cell-specific conditional KO, passive transfer, Gd-IgA1 ELISA, kidney histology","pmids":["41905596"],"confidence":"Medium","gaps":["Additional factors enabling mesangial deposition not identified","Mucosal-origin IgA1 properties driving deposition undefined"]},{"year":null,"claim":"How upstream signaling (cytokine, NF-κB, miRNA) and post-translational regulation are integrated to set tissue-specific C1GALT1 activity, and whether the Cosmc-bound 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Randomization","date":"2025-10-28","source":"bioRxiv","url":"https://doi.org/10.1101/2025.10.25.25338806","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2025.08.01.668091","title":"CD276 Immature Glycosylation Drives Colorectal Cancer Aggressiveness and T-cell Mediated Immune Escape","date":"2025-08-02","source":"bioRxiv","url":"https://doi.org/10.1101/2025.08.01.668091","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2024.10.07.617053","title":"Acute GARP depletion disrupts vesicle transport, leading to severe defects in sorting, secretion, and 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Substrate binding is primarily driven by the GalNAc moiety while the peptide sequence provides optimal kinetic and binding parameters. C1GalT1 recognizes a high-energy conformation of the α-GalNAc-Thr linkage (normally negligibly populated in solution), and by imposing this 3D arrangement—characteristic of α-GalNAc-Ser peptides—it ensures broad glycosylation of both Ser and Thr acceptor substrates.\",\n      \"method\": \"X-ray crystallography of enzyme–glycopeptide complex, biophysical assays, cellular studies, site-directed mechanistic analysis\",\n      \"journal\": \"Nature Communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure with functional validation plus biophysical and cellular orthogonal methods in a single rigorous study\",\n      \"pmids\": [\"35504880\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"The ER-localized molecular chaperone Cosmc directly interacts with partly denatured (non-native) T-synthase in vitro to cause partial restoration of T-synthase activity, in an ATP-independent fashion. A mutated Cosmc found in Tn-syndrome patients has reduced chaperone function. Cosmc is specific for T-synthase and does not act on another β-galactosyltransferase tested, representing the first ER chaperone identified for folding of a glycosyltransferase.\",\n      \"method\": \"In vitro chaperone refolding assay, mutagenesis of patient-derived Cosmc variant, activity assay\",\n      \"journal\": \"The Journal of Biological Chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution with mutagenesis, replicated across multiple papers from same lab with orthogonal methods\",\n      \"pmids\": [\"19923218\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Cosmc binds specifically to non-native (denatured) T-synthase but not to the active dimeric form. The Cosmc–T-synthase complex is relatively stable, forms in an ATP-independent manner not regulated by redox, calcium, pH, or intermolecular disulfide bonds, and leads to partial reactivation of T-synthase. Active T-synthase remains tightly noncovalently bound to Cosmc; dissociation is promoted in a client-driven process by further interactions with free native or non-native T-synthase.\",\n      \"method\": \"In vitro binding assays using recombinant proteins (free and solid-support-immobilized Cosmc), activity measurements, biochemical characterization\",\n      \"journal\": \"The Journal of Biological Chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution with multiple orthogonal biochemical methods; mechanistic model confirmed in same study\",\n      \"pmids\": [\"22416136\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"A specific linear, relatively hydrophobic peptide motif (CBRT) in the N-terminal stem region of T-synthase is required for binding to Cosmc. A synthetic CBRT peptide directly binds Cosmc and inhibits Cosmc-assisted refolding of denatured T-synthase. Mutations within CBRT diminish Cosmc binding and result in formation of inactive T-synthase. Inserting the T-synthase stem region into the unrelated β4GalT1 confers Cosmc binding on that chimera, confirming CBRT as a sequence-specific chaperone recognition motif.\",\n      \"method\": \"Deletion mutagenesis, synthetic peptide binding assay, in vitro refolding assay, domain-swap chimera experiment\",\n      \"journal\": \"The Journal of Biological Chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — mutagenesis plus in vitro assays plus domain-swap validation, multiple orthogonal methods in one study\",\n      \"pmids\": [\"24616093\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Immunocytochemical analysis demonstrated that C1GalT (T-synthase) is localized in the Golgi apparatus, while its chaperone Cosmc resides in the endoplasmic reticulum. In cells with a Cosmc loss-of-function missense mutation (LSC cells), C1GalT protein is absent; proteasome inhibition restores C1GalT protein but it fails to reach the Golgi. Overexpression of Cosmc (but not C1GalT itself) restores correct Golgi localization of C1GalT and recovers core 1 synthase activity, demonstrating that Cosmc controls intracellular trafficking and active localization of C1GalT.\",\n      \"method\": \"Immunocytochemistry with specific monoclonal antibodies, proteasome inhibitor treatment, overexpression rescue, activity assay\",\n      \"journal\": \"Biochemical and Biophysical Research Communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct localization experiments with functional consequence (activity rescue), multiple orthogonal approaches\",\n      \"pmids\": [\"18061573\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Targeted disruption of the T-synthase gene (C1galt1) in mice causes embryonic lethality by E14 due to defective angiogenesis: T-synthase-null embryos express unsialylated Tn antigen instead of sialyl-T antigen in endothelial, hematopoietic, and epithelial cells and develop brain hemorrhage with chaotic microvascular networks, distorted capillary lumens, and defective pericyte–endothelial cell–ECM associations, revealing an essential requirement for core 1-derived O-glycans in angiogenesis.\",\n      \"method\": \"Gene targeting (knockout mice), immunostaining, vascular morphology analysis\",\n      \"journal\": \"Methods in Enzymology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knockout with defined developmental phenotype and mechanistic cellular readout\",\n      \"pmids\": [\"17113876\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"A hypomorphic loss-of-function point mutation in C1galt1 in plt1 mice causes recessive thrombocytopenia and kidney disease. GPIbα in platelets and podocalyxin in kidney were identified as major underglycosylated targets of C1GalT1, indicating that proper O-glycosylation of these substrates is essential for platelet production and kidney function. Thrombocytopenia was not rescued on a lymphocyte-deficient background, indicating an intrinsic (non-immune-mediated) defect in megakaryocytes.\",\n      \"method\": \"ENU mutagenesis screen, genetic mapping, biochemical identification of underglycosylated substrates (GPIbα, podocalyxin), rag1-null epistasis\",\n      \"journal\": \"Proceedings of the National Academy of Sciences\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo loss-of-function with substrate identification and epistasis experiment, multiple orthogonal approaches\",\n      \"pmids\": [\"17062753\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Conditional ablation of C1galt1 in hematopoietic cells (Mx1-Cre) causes severe thrombocytopenia with giant platelets and prolonged bleeding times due to defective proplatelet formation during terminal megakaryocyte differentiation. GPIbα protein (but not mRNA) is significantly reduced in C1galt1-null megakaryocytes and platelets, suggesting increased proteolysis of under-O-glycosylated GPIbα. Circulating null platelets show increased microtubule coils despite normal tubulin levels.\",\n      \"method\": \"Conditional knockout (Mx1-Cre), bone marrow transplantation, flow cytometry, western blot, primary megakaryocyte culture\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional KO with multiple orthogonal methods and substrate-level mechanistic follow-up\",\n      \"pmids\": [\"23794065\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"C1GALT1 modifies O-glycans on the MET receptor tyrosine kinase in hepatocellular carcinoma cells (demonstrated by VVA and PNA lectin binding), enhancing HGF-induced MET dimerization and kinase activation. C1GALT1 overexpression enhanced HGF-induced MET phosphorylation and cell proliferation; C1GALT1 silencing suppressed MET phosphorylation and proliferation in vitro and in vivo. MET blockade abrogated C1GALT1-enhanced cell viability.\",\n      \"method\": \"RNAi knockdown and overexpression, lectin pull-down (VVA/PNA), phosphorylation assays, MET inhibitor epistasis, xenograft model\",\n      \"journal\": \"Cancer Research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — substrate identification by lectin pulldown plus functional epistasis with inhibitor and in vivo validation, multiple orthogonal methods\",\n      \"pmids\": [\"23832667\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"C1GALT1 modifies O-glycans on FGFR2 in colon cancer cells (first demonstration that FGFR2 carries O-glycans) and enhances bFGF-triggered FGFR2 phosphorylation and downstream malignant phenotypes. FGFR inhibitor BGJ398 blocked C1GALT1-enhanced effects, placing C1GALT1 upstream of FGFR2 activation.\",\n      \"method\": \"Lectin blotting, RNAi knockdown and overexpression, FGFR inhibitor epistasis, in vitro and xenograft assays\",\n      \"journal\": \"Oncotarget\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — substrate identification by lectin blotting plus pharmacological epistasis, single lab, two orthogonal approaches\",\n      \"pmids\": [\"24758762\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"C1GALT1 modifies O-glycans on integrin β1 in hepatocellular carcinoma cells and regulates integrin β1 activity and downstream signaling, thereby promoting cell adhesion to ECM, migration, and invasion. Anti-integrin β1 blocking antibody significantly suppressed C1GALT1-enhanced phenotypes, placing C1GALT1 upstream of integrin β1 activity.\",\n      \"method\": \"Lectin pull-down, RNAi knockdown and overexpression, integrin β1 blocking antibody epistasis, xenograft model\",\n      \"journal\": \"PLoS One\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — lectin-based substrate identification plus antibody epistasis, single lab, two orthogonal approaches\",\n      \"pmids\": [\"25089569\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"C1GALT1 modulates O-glycan structures on MUC1 in breast cancer cells and promotes MUC1-C/β-catenin signaling pathway activation, enhancing cell growth, migration, and invasion in vitro and tumor growth in vivo.\",\n      \"method\": \"Lectin blotting, RNAi knockdown and overexpression, pathway activation assays, xenograft model\",\n      \"journal\": \"Oncotarget\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — lectin-based substrate identification plus functional pathway assays, single lab\",\n      \"pmids\": [\"25762620\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"C1GALT1 modifies O-glycan structures on integrin β1 (β1-integrin) in esophageal cancer cells and regulates downstream FAK signaling. C1GALT1 knockdown increased radiosensitivity; β1-integrin blocking antibody and FAK inhibitor enhanced radiation-induced apoptosis, placing C1GALT1–β1-integrin–FAK in a radioresistance pathway.\",\n      \"method\": \"Lectin blotting, RNAi knockdown, integrin blocking antibody and FAK inhibitor epistasis, irradiation assays\",\n      \"journal\": \"Journal of Cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — substrate identification by lectin blotting plus pharmacological epistasis, single lab\",\n      \"pmids\": [\"30087707\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Disruption of C1galt1 in the KPC mouse pancreatic cancer model (KPCC mice) significantly accelerated PDAC development and metastasis. In human PDAC cells, C1GALT1 knockout via CRISPR/Cas9 caused aberrant glycosylation of MUC16 (identified by lectin pull-down and mass spectrometry) and upregulation of genes regulating tumorigenesis and metastasis.\",\n      \"method\": \"Conditional knockout in KPC mice (genetic epistasis), CRISPR/Cas9 KO, lectin pull-down, mass spectrometry, RNA sequencing, orthotopic model\",\n      \"journal\": \"Gastroenterology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo genetic model plus CRISPR KO with substrate identification by MS and transcriptomic analysis, multiple orthogonal methods\",\n      \"pmids\": [\"30086262\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"C1GALT1 modifies O-glycosylation on integrin α5 in gastric cancer cells (identified by lectin pull-down and mass spectrometry) and modulates activation of the PI3K/AKT pathway. Integrin α5 inhibition reversed C1GALT1-mediated tumor growth and metastasis in vitro and in vivo. Transcription factor SP1 was found to bind the C1GALT1 promoter and activate its expression, while miR-152 negatively regulates C1GALT1 by binding its 3′-UTR.\",\n      \"method\": \"Lectin pull-down, mass spectrometry, RNAi and overexpression, PI3K/AKT pathway assays, in vivo xenograft, ChIP/promoter binding, luciferase reporter\",\n      \"journal\": \"Cell & Bioscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — substrate identified by MS plus pathway epistasis, single lab, orthogonal methods\",\n      \"pmids\": [\"34452648\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"C1GALT1 O-glycosylates the Hedgehog signaling component Smoothened (SMO), thereby stabilizing SMO and stimulating Hedgehog pathway activity, which directly activates EWSR1::FLI1 transcription in Ewing sarcoma cells. C1GALT1 was identified as required for EWSR1::FLI1 expression by genome-scale CRISPR/Cas9 knockout screening, and its pharmacological inhibition (itraconazole) reduced EWSR1::FLI1 levels and suppressed ES xenograft growth.\",\n      \"method\": \"Genome-scale CRISPR/Cas9 KO screen, O-glycosylation assays, Hedgehog pathway assays, xenograft model, itraconazole pharmacological inhibition\",\n      \"journal\": \"Nature Communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — unbiased CRISPR screen plus substrate (SMO) glycosylation assays plus pathway epistasis plus in vivo pharmacological validation, multiple orthogonal methods\",\n      \"pmids\": [\"39894896\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Systematic peptide substrate profiling using oriented random glycopeptides revealed that T-synthase prefers Gly at the +1 position and Phe/Tyr at the +3 position relative to the acceptor Thr-O-GalNAc. Basic residues (Lys, Arg, His) in any position are disfavored, suggesting electrostatic interactions modulate transferase specificity.\",\n      \"method\": \"Oriented random glycopeptide library, PNA lectin affinity isolation, Edman amino acid sequencing, in vitro enzyme assay\",\n      \"journal\": \"Glycobiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro enzyme assay with systematic substrate library, rigorous quantitative analysis, single lab\",\n      \"pmids\": [\"19073881\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"The C. elegans ortholog Ce-T-synthase (encoded by C38H2.2, 42.7% identity to human T-synthase) was cloned and shown to be a functional ortholog: it catalyzes addition of Gal to GalNAc-Ser/Thr to form core 1 O-glycans. Unlike vertebrate T-synthase, Ce-T-synthase does not require the Cosmc chaperone and instead requires invertebrate-specific factors for optimal activity.\",\n      \"method\": \"cDNA cloning, recombinant expression in mammalian and insect cells, enzyme activity assay, promoter-GFP analysis\",\n      \"journal\": \"Glycobiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro enzymatic characterization of ortholog with Cosmc-independence established experimentally, single lab\",\n      \"pmids\": [\"16762980\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"The human C1GALT1 (T-synthase) promoter lacks a TATA box but contains a CpG island (tCpG) whose core promoter contains two binding sites for SP1/SP3 (Krüppel-like transcription factors). SP1/SP3 binding drives basal transcription of C1GALT1, as demonstrated by luciferase reporter assays, site-directed mutagenesis of binding sites, ChIP assays, and mithramycin A treatment. Unlike Cosmc, the T-synthase promoter CpG island is not hypermethylated in Tn-syndrome B cells, indicating differential epigenetic regulation.\",\n      \"method\": \"Luciferase reporter assay, site-directed mutagenesis, ChIP assay, mithramycin A treatment, methylome analysis\",\n      \"journal\": \"The Journal of Biological Chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (reporter, mutagenesis, ChIP, methylome) establishing transcriptional mechanism in a single study\",\n      \"pmids\": [\"26063800\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"IL-6 and IL-4 cytokines reduce IgA1 galactosylation directly by decreasing C1GalT1 expression and indirectly by increasing ST6GalNAc-II expression (which sialylates the GalNAc substrate, preventing C1GalT1-mediated galactosylation). These findings were confirmed by siRNA knockdown of C1GALT1 and ST6GalNAc-II genes and by in vitro enzyme reactions.\",\n      \"method\": \"siRNA knockdown, cytokine treatment of IgA1-secreting cells, in vitro enzyme reactions, O-glycan analysis\",\n      \"journal\": \"The Journal of Biological Chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — siRNA plus in vitro enzyme reactions plus glycan analysis, multiple orthogonal methods confirming mechanism\",\n      \"pmids\": [\"24398680\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Knockdown of C1galt1 (T-synthase) in corneal keratinocytes increased endocytic uptake of plasma membrane proteins via clathrin-mediated endocytosis (blocked by dynasore, nocodazole, chlorpromazine, and hyperosmotic sucrose), demonstrating that core 1 O-glycans contribute to apical barrier function by preventing clathrin-coated pit-mediated endocytosis.\",\n      \"method\": \"Tetracycline-inducible RNAi, cell surface biotinylation, subcellular fractionation, confocal microscopy, fluorescent nanosphere uptake, pharmacological inhibitors\",\n      \"journal\": \"PLoS One\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization/trafficking experiment with functional consequence and pharmacological epistasis, single lab, multiple methods\",\n      \"pmids\": [\"22574202\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"CRISPR/Cas9 knockout of T-synthase (C1GALT1) in colorectal cancer HCT116 cells induced Tn antigen expression and enhanced proliferation, adhesion, migration, and invasion. T-synthase deficiency directly induced epithelial-to-mesenchymal transition (EMT) with decreased E-cadherin and increased snail and fibronectin expression.\",\n      \"method\": \"CRISPR/Cas9 KO, flow cytometry, western blot, invasion/migration assays, EMT marker analysis\",\n      \"journal\": \"BioMed Research International\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — CRISPR KO with defined EMT phenotypic readout, single lab\",\n      \"pmids\": [\"30035127\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"The UDP-galactose transporter SLC35A2 (UGT) physically associates with C1GalT1 (T-synthase) in HEK293T cells. SLC35A2 also associates with Cosmc. In SLC35A2-deficient cells, C1GalT1 and Cosmc protein levels are decreased, their Golgi localization is less pronounced, and O-glycosylation is reduced. Endogenous Cosmc was found to localize in both the ER and Golgi apparatus of wild-type cells.\",\n      \"method\": \"Co-immunoprecipitation, western blot, immunofluorescence microscopy, SLC35A2 KO cells, subcellular fractionation\",\n      \"journal\": \"Biochimica et Biophysica Acta – Molecular Cell Research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — Co-IP plus localization with KO consequence, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"36933771\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"miR-124-3p directly targets T-synthase (C1GALT1) mRNA, reducing T-synthase protein expression in aged colon, disrupting O-glycosylation of mucins, compromising the colonic mucus barrier, and increasing susceptibility to colitis. Young mice overexpressing miR-124-3p phenocopied aged-colon glycosylation defects and developed more severe colitis.\",\n      \"method\": \"miRNA target validation, miR-124-3p overexpression in vivo, western blot, O-glycan analysis, colitis scoring\",\n      \"journal\": \"Aging Cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct miRNA targeting experiment with in vivo phenotypic readout, single lab\",\n      \"pmids\": [\"33040455\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"C1GalT1 undergoes O-GlcNAc modification at Thr229 and Thr233. This O-GlcNAcylation stabilizes C1GalT1 protein and strengthens its interaction with Cosmc. Mutation at these residues attenuates C1GalT1 stability and promotes its degradation via the proteasome pathway.\",\n      \"method\": \"O-GlcNAc modification identification, site-directed mutagenesis (Thr229/Thr233), Co-IP with Cosmc, proteasome inhibitor treatment, western blot\",\n      \"journal\": \"Acta Biochimica et Biophysica Sinica\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — PTM identification with mutagenesis plus interaction assays, single lab, two orthogonal methods\",\n      \"pmids\": [\"39126245\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"C1GALT1 knockdown decreased terminal galactose O-glycosylation and phosphorylation of EGFR in glioblastoma cells, attenuated downstream AKT/ERK phosphorylation, and reduced expression of cyclin D1 and MMP9. Transcription factor SP1 was found to bind the C1GALT1 promoter and regulate its expression in glioma.\",\n      \"method\": \"siRNA knockdown, O-glycan analysis, EGFR and AKT/ERK phosphorylation assays, xenograft model, SP1 promoter binding analysis\",\n      \"journal\": \"Cellular Signalling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — substrate glycosylation and downstream pathway assays with KD and in vivo validation, single lab\",\n      \"pmids\": [\"39561885\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"T-synthase knockdown via shRNA induced galectin-1 secretion both in vitro and in vivo, enhanced Th2 cytokine (IL-10 and IL-4) production, and promoted CD8+ T-cell apoptosis through galectin-1, prolonging skin allograft survival in mice. This places C1GALT1 upstream of galectin-1-mediated immune suppression.\",\n      \"method\": \"shRNA knockdown in CT26 cells and in vivo (intramuscular electroporation), ELISA for cytokines/galectin-1, apoptosis assays, skin allograft survival model\",\n      \"journal\": \"Journal of Clinical Immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo KD with defined immune phenotype and mechanistic pathway placement via galectin-1, single lab\",\n      \"pmids\": [\"22392045\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"In vivo experiment using B cell-specific C1galt1 knockout in a human IGHA1 knock-in mouse demonstrated that loss of C1galt1 in B cells markedly elevated circulating Gd-IgA1 under physiological and inflammatory conditions but did not substantially enhance glomerular IgA deposition, indicating that galactose-deficient IgA1 per se is not sufficient to drive glomerular deposition. In a passive transfer model, mucosal-origin IgA1 induced stronger mesangial deposition than serum or myeloma IgA1 despite similar or lower Gd-IgA1 content.\",\n      \"method\": \"B cell-specific conditional knockout, passive transfer model, ELISA for Gd-IgA1, kidney histology, flow cytometry\",\n      \"journal\": \"Kidney International\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo conditional KO with defined molecular and histological readouts, single study\",\n      \"pmids\": [\"41905596\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"Inhibition of NF-κB/p65 by a selective IKKβ inhibitor (TPCA-1) in EBV-immortalized IgA1-producing B cells reduced C1GALT1 gene expression and increased Gd-IgA1 production. Co-localization of NF-κB/p65 with transcription factor SP1 was altered in nuclei, suggesting the NF-κB pathway regulates IgA1 O-glycosylation via SP1-mediated transcriptional control of C1GALT1.\",\n      \"method\": \"IKKβ inhibitor treatment, flow cytometry, imaging, gene expression analysis, nuclear translocation assay\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — pharmacological inhibitor with correlative SP1 co-localization, single lab, preprint, no direct ChIP or mutagenesis confirming SP1–C1GALT1 link\",\n      \"pmids\": [\"42146603\"],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"C1GALT1 (T-synthase) is an obligate GT-A fold dimeric inverting glycosyltransferase that resides in the Golgi apparatus and catalyzes transfer of galactose from UDP-Gal to GalNAc-Ser/Thr to form the core 1 O-glycan (Galβ1-3GalNAcα-Ser/Thr), a process essential for angiogenesis, megakaryocyte differentiation, and epithelial barrier integrity; its activity depends on prior folding by the ER-specific chaperone Cosmc, which binds a hydrophobic stem-region motif (CBRT) in non-native T-synthase, restores activity in an ATP-independent client-driven cycle, and enables correct Golgi trafficking; C1GALT1 is transcriptionally driven by SP1/SP3 binding to a CpG-island core promoter and is post-translationally stabilized by O-GlcNAcylation at Thr229/Thr233; in cancer contexts it O-glycosylates multiple receptor substrates including MET, FGFR2, integrin β1, integrin α5, MUC1, MUC16, Smoothened, and EGFR, modifying their dimerization, activation, and downstream signaling (HGF/MET, bFGF/FGFR2, integrin/FAK, PI3K/AKT, Hedgehog/EWSR1::FLI1, AKT/ERK) to broadly promote or suppress cancer progression in a context-dependent manner.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"C1GALT1 (T-synthase) is a Golgi-resident inverting glycosyltransferase that catalyzes the committed step of mucin-type O-glycan extension, transferring galactose from UDP-Gal onto GalNAc-Ser/Thr to form the core 1 structure (Galβ1-3GalNAcα-Ser/Thr) [#0, #4]. Crystallographic and biophysical analysis shows it functions as an obligate GT-A fold dimer using an SN2 inverting mechanism, with substrate recognition driven primarily by the GalNAc moiety; the enzyme imposes a high-energy conformation on the α-GalNAc-Thr linkage to glycosylate both Ser and Thr acceptors, with peptide context (Gly at +1, Phe/Tyr at +3) tuning specificity [#0, #16]. Maturation of vertebrate T-synthase requires the ER-specific chaperone Cosmc, which binds a hydrophobic stem-region motif (CBRT) only in non-native enzyme, restores activity in an ATP-independent client-driven cycle, and is required for productive Golgi trafficking and active localization [#1, #2, #3, #4]. The enzyme is transcriptionally driven by SP1/SP3 acting on a CpG-island core promoter [#18] and is post-translationally stabilized by O-GlcNAcylation at Thr229/Thr233, which also reinforces the Cosmc interaction and protects against proteasomal degradation [#24]. Core 1 O-glycans generated by C1GALT1 are essential in vivo: genetic loss causes embryonic-lethal angiogenic failure [#5] and, in hematopoietic and renal cells, underglycosylation of substrates such as GPIbα and podocalyxin producing thrombocytopenia and kidney disease [#6, #7]. In cancer the enzyme O-glycosylates numerous cell-surface receptors—MET, FGFR2, integrins β1 and α5, MUC1, MUC16, Smoothened and EGFR—to modulate their stability, dimerization, activation and downstream signaling (HGF/MET, bFGF/FGFR2, integrin/FAK, PI3K/AKT, Hedgehog, AKT/ERK), driving context-dependent tumor progression or, in pancreatic cancer, tumor suppression [#8, #9, #13, #14, #15, #25]. Reduced C1GALT1 activity also underlies galactose-deficient IgA1 production relevant to IgA nephropathy [#19, #27].\"\n,\n  \"teleology\": [\n    {\n      \"year\": 2006,\n      \"claim\": \"Establishing that core 1 O-glycans are physiologically essential, not merely structural decoration, anchored the enzyme's biological importance.\",\n      \"evidence\": \"Gene targeting and ENU hypomorphic mutation in mice with vascular and hematopoietic/renal phenotypes\",\n      \"pmids\": [\"17113876\", \"17062753\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not define the molecular catalytic mechanism\", \"Substrate scope beyond GPIbα/podocalyxin not resolved in these studies\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Defining the spatial logic—ER chaperone versus Golgi enzyme—showed that the enzyme's activity is gated by trafficking, not just expression.\",\n      \"evidence\": \"Immunocytochemistry, proteasome inhibition, and Cosmc overexpression rescue in mutant cells\",\n      \"pmids\": [\"18061573\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis of Cosmc recognition not yet identified\", \"Did not address trafficking machinery beyond Cosmc\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Direct in vitro reconstitution proved Cosmc is a bona fide folding chaperone specific for T-synthase, explaining Tn-syndrome at the protein-folding level.\",\n      \"evidence\": \"In vitro chaperone refolding assays with patient-derived Cosmc mutant and activity measurements\",\n      \"pmids\": [\"19923218\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Recognition motif on T-synthase not yet mapped\", \"Mechanism of client release undefined at this stage\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Characterizing the binding/release cycle established that Cosmc operates ATP-independently in a client-driven manner, distinguishing it from canonical chaperones.\",\n      \"evidence\": \"In vitro binding and activity assays with recombinant immobilized Cosmc and free/non-native T-synthase\",\n      \"pmids\": [\"22416136\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of the complex not resolved\", \"In-cell kinetics of the cycle not measured\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Mapping the CBRT stem-region motif and validating it by domain swap defined the sequence determinant of chaperone specificity.\",\n      \"evidence\": \"Deletion mutagenesis, synthetic peptide binding/inhibition, and β4GalT1 chimera transfer\",\n      \"pmids\": [\"24616093\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structure of the CBRT–Cosmc interface unresolved\", \"How CBRT recognition discriminates native vs non-native states not detailed\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Systematic acceptor-peptide profiling defined the sequence context that tunes T-synthase specificity beyond the GalNAc anchor.\",\n      \"evidence\": \"Oriented random glycopeptide library with PNA affinity isolation, Edman sequencing, and in vitro enzyme assay\",\n      \"pmids\": [\"19073881\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural rationale for +1/+3 preferences provided only later\", \"Does not address in-cell substrate selection\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"The crystal structure unified prior biochemistry by revealing an obligate GT-A dimer, SN2 inverting catalysis, and the conformational trick allowing dual Ser/Thr glycosylation.\",\n      \"evidence\": \"X-ray crystallography of enzyme–glycopeptide complex with biophysical and cellular validation\",\n      \"pmids\": [\"35504880\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not capture the Cosmc-bound non-native state\", \"In-cell conformational dynamics not addressed\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Identifying SP1/SP3 at a CpG-island core promoter defined the basal transcriptional control distinct from Cosmc's epigenetic regulation.\",\n      \"evidence\": \"Luciferase reporter, site-directed mutagenesis, ChIP, mithramycin A treatment, methylome analysis\",\n      \"pmids\": [\"26063800\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Upstream signals controlling SP1/SP3 at this promoter not defined here\", \"Tissue-specific regulation not addressed\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Discovery of O-GlcNAcylation at Thr229/Thr233 established a post-translational layer that stabilizes the enzyme and reinforces Cosmc binding.\",\n      \"evidence\": \"O-GlcNAc mapping, site-directed mutagenesis, Co-IP with Cosmc, proteasome inhibition\",\n      \"pmids\": [\"39126245\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Enzymes adding/removing this modification not identified\", \"Single-lab finding without structural confirmation\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Linking the enzyme to the UDP-galactose transporter SLC35A2 connected nucleotide-sugar supply to enzyme stability and Golgi localization.\",\n      \"evidence\": \"Co-immunoprecipitation, immunofluorescence, and SLC35A2-KO cell analysis\",\n      \"pmids\": [\"36933771\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Co-IP without reciprocal/structural validation of the interaction\", \"Whether association is direct or complex-mediated unresolved\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Identifying receptor substrates (MET, GPIbα) showed that core 1 glycosylation directly modulates receptor activation and protein stability, extending the enzyme into signaling and platelet biology.\",\n      \"evidence\": \"Lectin pull-down, RNAi/overexpression, phosphorylation and inhibitor epistasis, conditional KO, xenograft\",\n      \"pmids\": [\"23832667\", \"23794065\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specific O-glycan sites on receptors not mapped\", \"Generalizability across receptor classes not yet tested\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"A series of cancer studies established a recurring theme: C1GALT1 glycosylates surface receptors (FGFR2, integrins β1/α5, MUC1/MUC16) to tune adhesion and growth-factor signaling, with context-dependent pro- or anti-tumor outcomes.\",\n      \"evidence\": \"Lectin pull-down/MS substrate identification, pathway and inhibitor epistasis, CRISPR KO, in vivo models\",\n      \"pmids\": [\"24758762\", \"25089569\", \"25762620\", \"30087707\", \"30086262\", \"34452648\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Most substrate identifications rely on lectin-based assays from single labs\", \"Determinants of pro- vs anti-tumor outcome not mechanistically resolved\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"An unbiased CRISPR screen placed C1GALT1 upstream of an oncogenic fusion by showing it glycosylates and stabilizes Smoothened to drive Hedgehog-dependent EWSR1::FLI1 expression, nominating it as a druggable dependency.\",\n      \"evidence\": \"Genome-scale CRISPR KO screen, SMO O-glycosylation assays, Hedgehog pathway epistasis, itraconazole, xenograft\",\n      \"pmids\": [\"39894896\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"SMO O-glycan sites not defined\", \"Specificity of itraconazole for the C1GALT1 axis not fully isolated\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"B cell-specific knockout in a humanized IgA1 model refined the role in IgA nephropathy, showing galactose-deficient IgA1 alone is insufficient for glomerular deposition.\",\n      \"evidence\": \"B cell-specific conditional KO, passive transfer, Gd-IgA1 ELISA, kidney histology\",\n      \"pmids\": [\"41905596\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Additional factors enabling mesangial deposition not identified\", \"Mucosal-origin IgA1 properties driving deposition undefined\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How upstream signaling (cytokine, NF-κB, miRNA) and post-translational regulation are integrated to set tissue-specific C1GALT1 activity, and whether the Cosmc-bound non-native state can be structurally resolved, remain open.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No structure of the Cosmc–T-synthase folding complex\", \"Integration of transcriptional, miRNA, and PTM control not unified\", \"Receptor O-glycan site maps largely missing\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [0, 4, 16, 17]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [8, 9, 15, 25]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [4, 22]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [0, 4]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [8, 9, 14, 15, 25]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [5, 6, 7]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"COSMC\", \"SLC35A2\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}