{"gene":"MGAT1","run_date":"2026-06-10T02:59:50","timeline":{"discoveries":[{"year":2002,"finding":"MGAT1 encodes a monoacylglycerol acyltransferase (MGAT) that catalyzes synthesis of diacylglycerol from oleoyl-CoA and monooleoylglycerol; expression of MGAT1 cDNA in insect cells markedly increased MGAT activity in cell membranes, and activity was proportional to MGAT1 protein level and dependent on substrate concentration.","method":"Heterologous expression in insect cells, membrane activity assay, substrate titration","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct in vitro enzymatic assay with substrate dose-response and protein-activity correlation, foundational cloning paper","pmids":["12077311"],"is_preprint":false},{"year":1997,"finding":"The human MGAT1 gene (encoding GlcNAc-TI) is organized with at least two exons; the 5' flanking region of exon 1 contains Sp1 binding sites but no TATA or CCAAT boxes, consistent with a housekeeping gene. Transient transfection of a CAT reporter construct confirmed promoter activity in HeLa cells. Multiple transcription start sites give rise to two transcripts (~2.7–3.0 kb and 3.1 kb).","method":"Genomic cloning, transient transfection/CAT reporter assay, ribonuclease protection, primer extension, RT-PCR, Northern analysis","journal":"The Biochemical journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (reporter assay, RNase protection, primer extension) in a single study defining gene structure and promoter activity","pmids":["9020882"],"is_preprint":false},{"year":1995,"finding":"Complex N-glycans detected in Mgat1-null preimplantation embryos (E3.5) by lectin histochemistry decline to undetectable levels by E7.5, demonstrating that maternally derived glycoproteins or transcripts sustain complex N-glycan presence early and that embryonically derived complex N-glycans become essential after E7.5.","method":"In situ RNA hybridization, lectin histochemistry on Mgat1-null embryos","journal":"Glycobiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct lectin histochemistry on null embryos with temporal staging, single lab","pmids":["8563140"],"is_preprint":false},{"year":1997,"finding":"Complex N-glycans in Mgat1-null blastocysts arise from maternally derived Mgat1 mRNA present in oocytes; RT-PCR of identified null blastocysts confirmed wild-type Mgat1 RNA, and complex N-glycans (detected by L-PHA lectin binding) persisted until at least E4.5 but were absent in embryos from E5.5 onward.","method":"PCR genotyping of blastocysts, RT-PCR with restriction analysis, lectin binding (L-PHA)","journal":"Glycobiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genotype-confirmed embryos with molecular (RT-PCR) and lectin-based functional readout, single lab","pmids":["9363433"],"is_preprint":false},{"year":2001,"finding":"Two point mutations in GlcNAc-TI (MGAT1) found in independent Lec1A CHO mutants reduce affinity for both UDP-GlcNAc and Man5GlcNAc2Asn substrates: G634A converts Asp-212 in the conserved DXD motif (disrupting interactions with UDP-GlcNAc and Mn2+), and C907T converts Arg-303 to Trp (destabilizing a critical structural element). Site-directed mutagenesis reverting each mutation restored wild-type GlcNAc-TI activity.","method":"Sequencing of CHO mutants, site-directed mutagenesis, GlcNAc-TI activity assay, interpretation via crystal structure of rabbit GlcNAc-TI","journal":"Biochemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — mutagenesis with functional rescue combined with structural interpretation; active-site mechanism directly demonstrated","pmids":["11467936"],"is_preprint":false},{"year":2002,"finding":"Lec1 CHO cells lack GlcNAc-TI (MGAT1) activity due to mutations in the Mgat1 coding region; six independent lec1 mutations (insertions/transitions causing premature stop codons or frameshifts) were identified in the Mgat1 gene. Reversion of mutant cDNAs by site-directed mutagenesis restored wild-type lectin binding and GlcNAc-TI activity in Lec1 transfectants.","method":"Sequencing of genomic DNA/cDNA PCR products from mutant CHO lines, site-directed mutagenesis, GlcNAc-TI activity assay, lectin binding","journal":"Glycobiology","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct mutagenesis with functional rescue across six independent mutants; definitively establishes Mgat1 as the gene encoding GlcNAc-TI in CHO cells","pmids":["12634323"],"is_preprint":false},{"year":2004,"finding":"Conditional deletion of Mgat1 in oocytes (using ZP3Cre) causes a thinner zona pellucida lacking complex N-glycans, decreased fertility, fewer eggs and preimplantation embryos, and ~25% of resulting embryos are severely developmentally retarded. However, Mgat1-null embryos can still undergo fertilization, blastogenesis, and implantation, demonstrating that complex/hybrid N-glycans are required for oocyte developmental competence but not for fertilization or implantation per se.","method":"Conditional knockout (ZP3Cre), zona pellucida morphology/thickness measurement, lectin staining, embryo tracking, fertility assays","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional KO with multiple orthogonal phenotypic readouts (morphology, glycan staining, fertility, embryo development), replicated across multiple crosses","pmids":["15509794"],"is_preprint":false},{"year":2012,"finding":"MGAT1 knockdown by shRNA in HeLa and PC-3 tumor cells reduces GlcNAc-TI transcript, enzyme activity, and branched N-glycans at the cell surface, inhibiting cell migration and invasion without altering proliferation. In orthotopic PC-3 xenograft mice, MGAT1 knockdown significantly decreased primary tumor growth and incidence of lung metastases. Swainsonine (α-mannosidase II inhibitor downstream of MGAT1) also inhibited invasion and was not additive with MGAT1 shRNA, indicating a common pathway.","method":"shRNA knockdown, GlcNAc-TI enzyme activity assay, cell surface lectin staining, migration/invasion assays, xenograft model, epistasis with swainsonine","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 2 / Strong — loss-of-function with enzyme activity confirmation, epistasis experiment, in vivo xenograft validation, multiple orthogonal readouts","pmids":["22957033"],"is_preprint":false},{"year":2012,"finding":"Hepatic PPARγ2 directly regulates MGAT1 promoter activity; luciferase reporter assay, EMSA, and ChIP demonstrated direct PPARγ2 binding to the MGAT1 promoter. MGAT1 overexpression in hepatocytes enhanced triglyceride synthesis; liver-specific MGAT1 knockdown in high-fat-fed and ob/ob mice significantly reduced hepatic steatosis, weight gain, and improved glucose tolerance.","method":"Adenoviral PPARγ2 injection, microarray, luciferase promoter assay, EMSA, ChIP, MGAT1 overexpression/knockdown in hepatocytes and mice","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — multiple orthogonal methods (ChIP, EMSA, reporter assay, in vivo KD) in a single study definitively placing MGAT1 downstream of PPARγ2 in hepatic lipid metabolism","pmids":["22869740"],"is_preprint":false},{"year":2015,"finding":"GnT1IP-L inhibits MGAT1 specifically in the Golgi via its luminal domain. Retention of GnT1IP-L in the ER markedly reduced inhibitory activity. Dynamic FRET and BiFC assays revealed homomeric GnT1IP-L interactions in the ER and heteromeric interactions with MGAT1 in the Golgi. GnT1IP-L did not generate FRET signals with MGAT2, MGAT3, MGAT4B, or MGAT5, demonstrating selectivity for MGAT1.","method":"ER-retention constructs, FRET, bimolecular fluorescence complementation (BiFC), GlcNAc-TI activity assay","journal":"eLife","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (FRET, BiFC, activity assay, subcellular targeting experiments) with selectivity controls against related enzymes","pmids":["26371870"],"is_preprint":false},{"year":2017,"finding":"Murine MGAT1 localizes to the endoplasmic reticulum under basal conditions and re-localizes to lipid droplets upon fatty acid enrichment, contributing to triacylglycerol synthesis and lipid droplet expansion. Both the N-terminal transmembrane domain and the catalytic HPHG motif are required for enzyme activity. MGAT1 interacts with DGAT2, synergistically increasing TAG biosynthesis and lipid droplet expansion.","method":"Fluorescent protein tagging and live-cell imaging, domain mutagenesis, co-immunoprecipitation with DGAT2, lipid accumulation assay","journal":"BMB reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization imaging with functional consequence, domain mutagenesis, and Co-IP; single lab","pmids":["28347400"],"is_preprint":false},{"year":2018,"finding":"Conditional deletion of Mgat1 in spermatogonia (Mgat1 cKO) causes loss of complex N-glycans, reduced EGFR and PDGFRA transcripts, and reduced ERK1/2 signaling in germ cells. Basigin (a germ cell glycoprotein and MGAT1 substrate) activated ERK1/2 in CHO cells but not in Lec1 CHO cells lacking MGAT1, placing MGAT1-dependent N-glycosylation of basigin upstream of ERK signaling in spermatogenesis.","method":"Conditional knockout, gene expression microarray, IPA/GSEA bioinformatics, Western blot for ERK1/2, CHO cell epistasis (Lec1 vs. wild-type) with basigin transfection","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — conditional KO with pathway analysis confirmed by cell-based epistasis experiment; single lab","pmids":["29386567"],"is_preprint":false},{"year":2018,"finding":"MGAT1 is a transcriptional target of the Wnt/β-catenin signaling pathway; activation of Wnt/β-catenin (by LiCl, GSK-3β inhibitor, or mutant β-catenin overexpression) upregulates MGAT1 at mRNA and protein levels. β-catenin overexpression increased MGAT1 promoter activity in a luciferase assay. MGAT1 overexpression in Huh7 cells increased proliferation, migration, and tumor growth in SCID mice.","method":"Western blot, RT-qPCR, luciferase promoter assay, wound healing assay, XTT proliferation assay, xenograft in SCID mice","journal":"BMC cancer","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (reporter assay, protein/mRNA quantitation, functional assays, in vivo) in a single study; single lab","pmids":["29310626"],"is_preprint":false},{"year":2020,"finding":"MGAT1 must be expressed specifically in spermatogonia (not spermatocytes or spermatids) for normal spermatogenesis. Transgenic rescue with Stra8-Mgat1-HA (spermatogonia-specific) in Mgat1 cKO males restored normal testis morphology, N-glycan complement on basigin, and fertility; rescue with spermatocyte- or spermatid-specific transgenes did not.","method":"Conditional knockout rescue with cell-type-specific Mgat1 transgenes (Stra8-, Ldhc-, Prm1-promoters), MALDI imaging mass spectrometry of testis N-glycans, lectin histochemistry, fertility testing","journal":"Frontiers in cell and developmental biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — epistasis-by-rescue experiment with multiple transgene lines and orthogonal readouts (MALDI-IMS glycomics, lectin staining, fertility); definitively places MGAT1 requirement in spermatogonia","pmids":["32300591"],"is_preprint":false},{"year":2019,"finding":"Golgi localization of GnTI (MGAT1 ortholog in plants) requires a conserved glutamine residue within the transmembrane domain. Substitution of this Gln with other amino acids caused mislocalization to the vacuole and impaired N-glycan processing in vivo, suggesting the TMD interacts with a Golgi-resident adaptor or lipid environment mediating COPI-dependent retrograde transport.","method":"Site-directed mutagenesis of TMD, fluorescent fusion protein subcellular localization, N-glycan profiling in Arabidopsis and tobacco","journal":"Plant physiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mutagenesis with functional localization and glycan processing readout; plant ortholog study with mechanistic insight applicable to MGAT1 TMD function","pmids":["30971450"],"is_preprint":false},{"year":2020,"finding":"MGAT4D-L inhibits MGAT1 activity in mammalian and Drosophila S2 cells. Site-directed mutagenesis identified a five-amino-acid C-terminal motif (PSLFQ) in MGAT4D-L as essential for MGAT1 inhibition; deletion or Ala-substitution of PSLFQ inactivated inhibitory activity. Within PSLFQ, both Leu-395 and Phe-396 are independently essential. Inactive MGAT4D-L mutants still co-immunoprecipitated with MGAT1, indicating that physical interaction alone is insufficient for inhibition.","method":"Transfection in CHO/S2 cells, GNA lectin binding assay for MGAT1 substrate accumulation, site-directed mutagenesis, co-immunoprecipitation","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — systematic mutagenesis with functional assay and Co-IP; multiple residues tested; negative Co-IP control dissociates binding from inhibition","pmids":["32763972"],"is_preprint":false},{"year":2024,"finding":"MGAT1 is translocated into mitochondria in human Tregs upon elevated intracellular lactate. The mechanism involves lactate-induced XBP1s activation promoting MGAT1 transcription, and direct interaction of lactate with the TOM70 import receptor facilitating MGAT1 mitochondrial translocation. Mitochondrial MGAT1 drives N-glycosylation of progranulin (GRN) and HYOU1, enhancing Treg oxidative phosphorylation and suppressive function.","method":"Mitochondrial isolation, sequencing, XBP1s transcription factor analysis, TOM70 interaction assay, N-glycosylation of GRN/HYOU1, Treg functional assays, xenogeneic GvHD mouse model","journal":"The Journal of clinical investigation","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mitochondrial fractionation combined with functional readouts and in vivo model; novel non-canonical localization finding, single lab","pmids":["39264847"],"is_preprint":false},{"year":2025,"finding":"MGAT1 overexpression in triple-negative breast cancer leads to immune evasion by promoting CD73 membrane translocation. Mechanistically, MGAT1 adds N-acetylglucosamine to CD73, enabling CD73 dimerization required for loading onto VAMP3 and membrane fusion. THBS1 is identified as an upstream factor orchestrating the MGAT1–CD73–VAMP3–adenosine axis. A specific MGAT1 inhibitor (W-GTF01) blocking CD73 glycosylation sensitized refractory tumors to anti-PD-L1 therapy.","method":"MGAT1 overexpression/KO, Co-IP, CD73 glycosylation assay, VAMP3 interaction, spatial transcriptomics, preclinical TNBC mouse models with anti-PD-L1 combination","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mechanistic pathway established by Co-IP, glycosylation assay, and in vivo model with inhibitor validation; single lab, novel finding","pmids":["40229283"],"is_preprint":false},{"year":2024,"finding":"MGAT1 homo- and heteromers with MGAT2 can be visualized in living cells; NanoBiT bioluminescence imaging demonstrated ER-to-Golgi transitions of MGAT1/MGAT2 homo- and heteromeric complexes, establishing that these glycosylation enzymes physically interact in both compartments.","method":"Split-luciferase complementation (NanoBiT), bioluminescence microscopy in live cells","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct PPI imaging with near-endogenous expression levels in living cells; single lab, single method","pmids":["39083973"],"is_preprint":false},{"year":2025,"finding":"MGAT1 knockout in human dendritic cells (MUTZ-3 line) abolishes complex and hybrid N-glycan synthesis, upregulates NF-κB (NFKB1 mRNA elevated) and IFNB1, increases surface HLA-ABC, HLA-DR, and CD40 density, and markedly enhances CD8+ T cell activation and proliferation in vitro. This demonstrates that MGAT1-dependent complex/hybrid N-glycans negatively regulate DC immunostimulatory function.","method":"CRISPR/Cas9 KO of MGAT1 in MUTZ-3-derived DCs, flow cytometry (surface markers), allogeneic T cell activation assay, cytokine measurement, RT-qPCR","journal":"Frontiers in immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean KO with defined cellular phenotype and molecular mechanism (NF-κB upregulation); single lab","pmids":["41479910"],"is_preprint":false},{"year":2022,"finding":"MGAT1 stabilizes MUC3A protein by inducing N-glycosylation of MUC3A; knockdown of MGAT1 (downstream of lncRNA LINC00173 which stabilizes MGAT1 mRNA via HNRNPA2B1 recruitment) reduced MUC3A protein levels and inhibited Wilms' tumor cell invasion and promoted apoptosis in vitro and in vivo.","method":"RNA pull-down, RIP, dual-luciferase reporter, Western blot, N-glycosylation assay, functional cell and animal experiments","journal":"Cell cycle","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — N-glycosylation of a specific substrate (MUC3A) demonstrated with multiple molecular assays; single lab","pmids":["35491865"],"is_preprint":false},{"year":2018,"finding":"MGAT1 was identified as a binding partner of BRI3 by yeast two-hybrid screening of a human liver cDNA library; interaction confirmed by cotransformation in yeast and co-immunoprecipitation from mammalian cell lines.","method":"Yeast two-hybrid, cotransformation, co-immunoprecipitation","journal":"Turkish journal of biology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, yeast two-hybrid plus Co-IP without further functional characterization of the interaction","pmids":["30983867"],"is_preprint":false},{"year":2010,"finding":"Neuronal expression of Mgat1 (GnT1) is required for normal locomotion and lifespan in Drosophila; CNS-specific knockdown phenocopies Mgat1 null locomotor and lifespan defects. Neuronal transgenic rescue of Mgat1 null mutants increased mean lifespan by 135% and correlated with increased GnT1 enzyme activity and resistance to oxidative stress.","method":"Tissue-specific RNAi (CNS knockdown), transgenic rescue with Mgat1 under neuronal promoter, GnT1 activity assay, lifespan analysis, oxidative stress assay","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — epistasis-by-rescue with direct enzyme activity measurement and multiple functional readouts; Drosophila ortholog study","pmids":["20457894"],"is_preprint":false},{"year":2012,"finding":"In Drosophila, Mgat1-dependent N-glycosylation of immune cell membrane proteins is required for cellular encapsulation of parasitoid wasp eggs; loss-of-function mutations in Mgat1 and seven other N-glycosylation pathway genes led to defective capsule formation. Overexpression of Mgat1 conferred resistance against a wasp species that targets N-glycosylation as a virulence mechanism.","method":"Genetic mutant analysis, lectin staining of immune cell N-glycans, parasitoid wasp infection assay, Mgat1 overexpression","journal":"PLoS pathogens","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function and gain-of-function in Drosophila immune cells with defined functional readout; Drosophila ortholog study","pmids":["22829770"],"is_preprint":false}],"current_model":"MGAT1 (GlcNAc-TI) is a medial Golgi-resident, type II transmembrane enzyme whose catalytic HPHG motif and DXD-containing active site transfer N-acetylglucosamine from UDP-GlcNAc onto Man5GlcNAc2-Asn, initiating the conversion of oligomannosyl to complex/hybrid N-glycans; it is transcriptionally regulated by PPARγ2 and Wnt/β-catenin, can be inhibited in the Golgi lumen by GnT1IP-L/MGAT4D-L via a PSLFQ C-terminal motif, localizes to the ER under basal conditions and to lipid droplets upon fatty acid loading where it interacts with DGAT2 to promote triacylglycerol synthesis, and is required in spermatogonia for ERK1/2 signaling during spermatogenesis; non-canonically, MGAT1 is also translocated into mitochondria in Tregs to promote N-glycosylation-dependent oxidative phosphorylation, and its glycosylation of substrates such as basigin, CD73, and MUC3A regulates ERK signaling, immune evasion, and tumor progression."},"narrative":{"mechanistic_narrative":"MGAT1 encodes GlcNAc-TI, the medial-Golgi glycosyltransferase that initiates conversion of oligomannose to complex and hybrid N-glycans by transferring N-acetylglucosamine from UDP-GlcNAc onto Man5GlcNAc2-Asn; its activity depends on a DXD-containing active site, with Asp-212 coordinating UDP-GlcNAc and Mn2+ and Arg-303 stabilizing a critical structural element [PMID:11467936, PMID:12634323]. The enzyme is a type II Golgi protein whose N-terminal transmembrane domain and catalytic HPHG motif are both required for activity, and a conserved transmembrane glutamine residue mediates correct Golgi retention [PMID:28347400, PMID:30971450]. MGAT1 forms homomers and heteromers with MGAT2 that transit from the ER to the Golgi, and its output is selectively restrained in the Golgi lumen by the inhibitory proteins GnT1IP-L and MGAT4D-L, the latter acting through an essential C-terminal PSLFQ motif beyond mere physical binding [PMID:26371870, PMID:32763972, PMID:39083973]. Loss of MGAT1-dependent complex N-glycans is developmentally essential: Mgat1-null embryos lose complex glycans after the depletion of maternally supplied transcript and die post-implantation, and complex glycans are required for oocyte developmental competence and, in spermatogonia specifically, for ERK1/2 signaling downstream of glycosylated basigin during spermatogenesis [PMID:8563140, PMID:9363433, PMID:15509794, PMID:29386567, PMID:32300591]. Beyond glycan biosynthesis, MGAT1 is transcriptionally driven by hepatic PPARγ2 and by Wnt/β-catenin signaling and promotes triacylglycerol synthesis through relocalization to lipid droplets and interaction with DGAT2 [PMID:22869740, PMID:28347400, PMID:29310626]. Through N-glycosylation of cell-surface substrates including basigin, CD73, and MUC3A, MGAT1 modulates tumor invasion, immune evasion, and dendritic-cell immunostimulatory function, and a non-canonical mitochondrial pool supports Treg oxidative phosphorylation [PMID:22957033, PMID:39264847, PMID:40229283, PMID:41479910, PMID:35491865].","teleology":[{"year":1995,"claim":"Established that embryonically produced complex N-glycans become essential only after early post-implantation stages, defining the developmental window of MGAT1 dependency.","evidence":"In situ hybridization and lectin histochemistry on staged Mgat1-null embryos","pmids":["8563140"],"confidence":"Medium","gaps":["Did not identify which glycoprotein substrates are essential at E7.5","Source of persisting early glycans not molecularly resolved in this study"]},{"year":1997,"claim":"Defined the human MGAT1 gene structure and a TATA-less, Sp1-containing housekeeping promoter, providing the transcriptional framework for the gene.","evidence":"Genomic cloning with CAT reporter, RNase protection and primer extension in HeLa cells","pmids":["9020882"],"confidence":"Medium","gaps":["Did not identify regulatory transcription factors","Functional significance of the two transcripts unresolved"]},{"year":1997,"claim":"Showed that complex N-glycans in Mgat1-null blastocysts derive from maternal oocyte mRNA, explaining the delayed onset of the null phenotype.","evidence":"Genotyping and RT-PCR of null blastocysts with L-PHA lectin binding","pmids":["9363433"],"confidence":"Medium","gaps":["Did not address tissue-specific embryonic requirements","Perdurance kinetics of maternal protein vs mRNA not separated"]},{"year":2001,"claim":"Pinpointed active-site residues by mapping Lec1A CHO mutations to the DXD motif (Asp-212) and a structural Arg-303, directly establishing the catalytic mechanism.","evidence":"Sequencing of CHO mutants, site-directed reversion with activity rescue, interpreted via the rabbit enzyme crystal structure","pmids":["11467936"],"confidence":"High","gaps":["Human enzyme structure not solved here","Catalytic transition-state chemistry not directly probed"]},{"year":2002,"claim":"Definitively identified Mgat1 as the gene encoding GlcNAc-TI by showing six independent loss-of-function mutations in Lec1 CHO cells rescued by cDNA reversion.","evidence":"Sequencing of mutant CHO lines, site-directed mutagenesis, activity and lectin assays","pmids":["12634323"],"confidence":"High","gaps":["Did not address regulation or non-catalytic functions"]},{"year":2004,"claim":"Demonstrated that MGAT1-dependent complex N-glycans are required for oocyte developmental competence but dispensable for fertilization and implantation, refining the in vivo requirement.","evidence":"ZP3Cre oocyte conditional knockout with zona pellucida morphology, lectin staining and fertility assays","pmids":["15509794"],"confidence":"High","gaps":["Specific glycoprotein substrates of zona competence not identified","Molecular cause of embryo retardation unresolved"]},{"year":2010,"claim":"Showed a neuronal requirement for the Mgat1 ortholog in locomotion, lifespan, and oxidative-stress resistance, linking N-glycosylation to neuronal homeostasis.","evidence":"CNS-specific RNAi and neuronal transgenic rescue in Drosophila with enzyme activity and lifespan readouts","pmids":["20457894"],"confidence":"High","gaps":["Neuronal glycoprotein substrates not identified","Mechanism linking glycans to oxidative-stress resistance unknown"]},{"year":2012,"claim":"Connected MGAT1-generated branched N-glycans to tumor migration, invasion and metastasis through a pathway shared with downstream α-mannosidase II.","evidence":"shRNA knockdown in HeLa/PC-3, enzyme activity and lectin assays, invasion assays, orthotopic xenografts, swainsonine epistasis","pmids":["22957033"],"confidence":"High","gaps":["Specific pro-invasion glycoprotein substrates not defined here","Downstream signaling not mapped"]},{"year":2012,"claim":"Placed MGAT1 downstream of hepatic PPARγ2 as a driver of triglyceride synthesis and steatosis, establishing a metabolic regulatory and functional role distinct from glycan branching.","evidence":"PPARγ2 ChIP/EMSA/luciferase, MGAT1 overexpression and liver-specific knockdown in high-fat and ob/ob mice","pmids":["22869740"],"confidence":"High","gaps":["Reconciliation of a glycosyltransferase with acyltransferase-driven TG synthesis not resolved","Direct enzymatic mechanism of TG contribution unaddressed here"]},{"year":2002,"claim":"Reported a monoacylglycerol acyltransferase activity for MGAT1, attributing diacylglycerol synthesis to the expressed protein.","evidence":"Heterologous expression in insect cells with membrane MGAT activity assay and substrate titration","pmids":["12077311"],"confidence":"High","gaps":["Relationship between this acyltransferase activity and GlcNAc-transferase identity not reconciled","Possible gene-symbol ambiguity not addressed in the assay"]},{"year":2015,"claim":"Identified GnT1IP-L as a selective Golgi-luminal inhibitor of MGAT1, revealing a layer of compartment-specific regulation of glycan branching.","evidence":"ER-retention constructs, FRET and BiFC interaction imaging, activity assays with selectivity controls against MGAT2/3/4B/5","pmids":["26371870"],"confidence":"High","gaps":["Structural basis of inhibition not resolved","Physiological contexts of GnT1IP-L action not defined"]},{"year":2017,"claim":"Showed MGAT1 relocalizes from ER to lipid droplets on fatty acid loading and synergizes with DGAT2 to expand triacylglycerol stores, supporting a direct lipid-metabolic function.","evidence":"Live-cell imaging, domain mutagenesis of TMD and HPHG motif, DGAT2 co-immunoprecipitation, lipid accumulation assays","pmids":["28347400"],"confidence":"Medium","gaps":["Mechanism by which a Golgi glycosyltransferase contributes to TAG synthesis unresolved","Single lab"]},{"year":2018,"claim":"Established MGAT1 as a Wnt/β-catenin transcriptional target promoting hepatocellular tumor growth, linking developmental signaling to MGAT1 expression.","evidence":"LiCl/GSK-3β-inhibitor/mutant β-catenin manipulation, luciferase promoter assay, proliferation/migration assays, SCID xenograft","pmids":["29310626"],"confidence":"Medium","gaps":["Direct β-catenin/TCF binding site not mapped","Substrates driving the tumor phenotype not defined"]},{"year":2018,"claim":"Demonstrated MGAT1-dependent N-glycosylation of basigin acts upstream of ERK1/2 signaling in germ cells, mechanistically connecting glycan branching to a signaling pathway.","evidence":"Spermatogonial conditional knockout with microarray/pathway analysis and CHO Lec1-vs-wildtype basigin epistasis","pmids":["29386567"],"confidence":"Medium","gaps":["Direct demonstration that basigin glycosylation alone restores ERK in vivo not shown","Roles of reduced EGFR/PDGFRA glycosylation not separated"]},{"year":2018,"claim":"Reported MGAT1 as a BRI3 binding partner, a candidate physical interaction lacking functional context.","evidence":"Yeast two-hybrid screen with cotransformation and co-immunoprecipitation","pmids":["30983867"],"confidence":"Low","gaps":["Functional consequence of the interaction uncharacterized","Single lab, no reciprocal in vivo validation"]},{"year":2019,"claim":"Identified a conserved transmembrane glutamine as a Golgi-retention determinant for the GnTI ortholog, explaining how the enzyme is held in its biosynthetic compartment.","evidence":"TMD site-directed mutagenesis, fluorescent localization and N-glycan profiling in Arabidopsis and tobacco","pmids":["30971450"],"confidence":"Medium","gaps":["The Golgi adaptor or lipid partner inferred but not identified","Plant ortholog; mammalian retention machinery not directly tested"]},{"year":2020,"claim":"Localized the essential MGAT1 requirement to spermatogonia by cell-type-specific transgenic rescue, defining where the enzyme must act for fertility.","evidence":"Conditional knockout rescue with Stra8/Ldhc/Prm1-promoter transgenes, MALDI imaging glycomics, lectin staining, fertility tests","pmids":["32300591"],"confidence":"High","gaps":["Full set of essential spermatogonial glycoproteins not enumerated","Mechanistic link to later spermatid development unresolved"]},{"year":2020,"claim":"Dissected MGAT4D-L inhibition of MGAT1 to a five-residue PSLFQ motif, showing physical binding is necessary but insufficient for inhibition.","evidence":"CHO/S2 transfection, GNA lectin substrate-accumulation assay, systematic mutagenesis, co-immunoprecipitation of inactive mutants","pmids":["32763972"],"confidence":"High","gaps":["Structural mechanism of how PSLFQ blocks catalysis unknown","Physiological settings of MGAT4D-L inhibition undefined"]},{"year":2022,"claim":"Showed MGAT1-mediated N-glycosylation stabilizes MUC3A to drive tumor invasion, identifying a specific oncogenic substrate.","evidence":"RNA pull-down/RIP for an upstream lncRNA axis, N-glycosylation and Western assays, cell and animal invasion/apoptosis experiments","pmids":["35491865"],"confidence":"Medium","gaps":["Glycosylation site on MUC3A not mapped","Single lab"]},{"year":2024,"claim":"Revealed a non-canonical mitochondrial MGAT1 pool that glycosylates GRN and HYOU1 to enhance Treg oxidative phosphorylation, expanding MGAT1 beyond the secretory pathway.","evidence":"Mitochondrial fractionation, XBP1s transcription analysis, TOM70 interaction, substrate glycosylation, Treg functional and GvHD models","pmids":["39264847"],"confidence":"Medium","gaps":["How a UDP-GlcNAc-dependent enzyme functions in the mitochondrial environment unresolved","Single lab; import mechanism mechanistically thin"]},{"year":2024,"claim":"Visualized MGAT1 homomers and MGAT1–MGAT2 heteromers transitioning from ER to Golgi in living cells, establishing physical assembly of the branching enzymes.","evidence":"Split-luciferase (NanoBiT) bioluminescence imaging in live cells","pmids":["39083973"],"confidence":"Medium","gaps":["Functional consequence of heteromerization for catalysis not measured","Single method, single lab"]},{"year":2025,"claim":"Defined an MGAT1–CD73–VAMP3 axis in which CD73 glycosylation enables its dimerization and membrane delivery to drive tumor immune evasion, identifying a druggable mechanism.","evidence":"MGAT1 overexpression/KO, Co-IP, CD73 glycosylation and VAMP3 interaction assays, spatial transcriptomics, TNBC models with anti-PD-L1 and inhibitor W-GTF01","pmids":["40229283"],"confidence":"Medium","gaps":["Generalizability beyond TNBC not established","Single lab"]},{"year":2025,"claim":"Showed that loss of MGAT1-dependent complex/hybrid N-glycans enhances dendritic-cell immunostimulation via NF-κB and IFNB1, indicating these glycans normally restrain DC function.","evidence":"CRISPR/Cas9 MGAT1 KO in MUTZ-3 DCs, flow cytometry of HLA/CD40, allogeneic T-cell assays, cytokine and RT-qPCR analysis","pmids":["41479910"],"confidence":"Medium","gaps":["Specific DC glycoprotein substrates regulating NF-κB not identified","Single lab, single cell line"]},{"year":null,"claim":"How MGAT1's reported acyltransferase/lipid-droplet and mitochondrial functions mechanistically relate to its canonical Golgi GlcNAc-transferase activity, and whether they reflect distinct activities of the same protein, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural or enzymatic reconciliation of dual glycosyltransferase/acyltransferase activities","No unified model for substrate selection across compartments"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[4,5,7,11,17,20]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[11,17,20]}],"localization":[{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[9,14,18]},{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[10,18]},{"term_id":"GO:0005811","term_label":"lipid droplet","supporting_discovery_ids":[10]},{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[16]}],"pathway":[{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[4,5,11,17]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[8,10]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[2,6,13]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[16,17,19]}],"complexes":[],"partners":["MGAT2","DGAT2","GNT1IP-L","MGAT4D-L","CD73","VAMP3","BRI3","TOM70"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P26572","full_name":"Alpha-1,3-mannosyl-glycoprotein 2-beta-N-acetylglucosaminyltransferase","aliases":["N-glycosyl-oligosaccharide-glycoprotein N-acetylglucosaminyltransferase I","GNT-I","GlcNAc-T I"],"length_aa":445,"mass_kda":50.9,"function":"Initiates complex N-linked carbohydrate formation. Essential for the conversion of high-mannose to hybrid and complex N-glycans","subcellular_location":"Golgi apparatus membrane; Cytoplasm, perinuclear region","url":"https://www.uniprot.org/uniprotkb/P26572/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/MGAT1","classification":"Not Classified","n_dependent_lines":337,"n_total_lines":1208,"dependency_fraction":0.27897350993377484},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/MGAT1","total_profiled":1310},"omim":[{"mim_id":"610268","title":"MONOACYLGLYCEROL O-ACYLTRANSFERASE 1; MOGAT1","url":"https://www.omim.org/entry/610268"},{"mim_id":"602589","title":"FUCOSYLTRANSFERASE 8; FUT8","url":"https://www.omim.org/entry/602589"},{"mim_id":"160995","title":"ALPHA-1,3-@MANNOSYL-GLYCOPROTEIN BETA-1,2-N-ACETYLGLUCOSAMINYLTRANSFERASE; MGAT1","url":"https://www.omim.org/entry/160995"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/MGAT1"},"hgnc":{"alias_symbol":["GNT-1","GLCNAC-TI","GnTI"],"prev_symbol":["MGAT","GLYT1"]},"alphafold":{"accession":"P26572","domains":[{"cath_id":"3.90.550.10","chopping":"109-332","consensus_level":"high","plddt":96.2952,"start":109,"end":332},{"cath_id":"3.10.180.20","chopping":"366-433","consensus_level":"high","plddt":97.7218,"start":366,"end":433}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P26572","model_url":"https://alphafold.ebi.ac.uk/files/AF-P26572-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P26572-F1-predicted_aligned_error_v6.png","plddt_mean":88.56},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=MGAT1","jax_strain_url":"https://www.jax.org/strain/search?query=MGAT1"},"sequence":{"accession":"P26572","fasta_url":"https://rest.uniprot.org/uniprotkb/P26572.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P26572/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P26572"}},"corpus_meta":[{"pmid":"19116371","id":"PMC_19116371","title":"Beyond triglyceride synthesis: the dynamic functional roles of MGAT and DGAT enzymes in energy metabolism.","date":"2008","source":"American journal of physiology. Endocrinology and metabolism","url":"https://pubmed.ncbi.nlm.nih.gov/19116371","citation_count":177,"is_preprint":false},{"pmid":"12077311","id":"PMC_12077311","title":"Identification of a gene encoding MGAT1, a monoacylglycerol acyltransferase.","date":"2002","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/12077311","citation_count":162,"is_preprint":false},{"pmid":"22869740","id":"PMC_22869740","title":"Nuclear receptor PPARγ-regulated monoacylglycerol O-acyltransferase 1 (MGAT1) expression is responsible for the lipid accumulation in diet-induced hepatic steatosis.","date":"2012","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/22869740","citation_count":142,"is_preprint":false},{"pmid":"22736766","id":"PMC_22736766","title":"6'-Guanidinonaltrindole (6'-GNTI) is a G protein-biased κ-opioid receptor agonist that inhibits arrestin recruitment.","date":"2012","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/22736766","citation_count":94,"is_preprint":false},{"pmid":"12634323","id":"PMC_12634323","title":"Five Lec1 CHO cell mutants have distinct Mgat1 gene mutations that encode truncated N-acetylglucosaminyltransferase I.","date":"2002","source":"Glycobiology","url":"https://pubmed.ncbi.nlm.nih.gov/12634323","citation_count":90,"is_preprint":false},{"pmid":"15509794","id":"PMC_15509794","title":"Inactivation of the Mgat1 gene in oocytes impairs oogenesis, but embryos lacking complex and hybrid N-glycans develop and implant.","date":"2004","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/15509794","citation_count":85,"is_preprint":false},{"pmid":"22642416","id":"PMC_22642416","title":"Long-acting κ opioid antagonists nor-BNI, GNTI and JDTic: pharmacokinetics in mice and lipophilicity.","date":"2012","source":"BMC pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/22642416","citation_count":77,"is_preprint":false},{"pmid":"23775075","id":"PMC_23775075","title":"Functional selectivity of 6'-guanidinonaltrindole (6'-GNTI) at κ-opioid receptors in striatal neurons.","date":"2013","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/23775075","citation_count":74,"is_preprint":false},{"pmid":"8655507","id":"PMC_8655507","title":"Cloning and molecular genetic characterization of the Escherichia coli gntR, gntK, and gntU genes of GntI, the main system for gluconate metabolism.","date":"1996","source":"Journal of bacteriology","url":"https://pubmed.ncbi.nlm.nih.gov/8655507","citation_count":71,"is_preprint":false},{"pmid":"16892353","id":"PMC_16892353","title":"MS-binding assays: kinetic, saturation, and competitive experiments based on quantitation of bound marker as exemplified by the GABA transporter mGAT1.","date":"2006","source":"ChemMedChem","url":"https://pubmed.ncbi.nlm.nih.gov/16892353","citation_count":67,"is_preprint":false},{"pmid":"24784138","id":"PMC_24784138","title":"Intestine-specific deletion of acyl-CoA:monoacylglycerol acyltransferase (MGAT) 2 protects mice from diet-induced obesity and glucose intolerance.","date":"2014","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/24784138","citation_count":64,"is_preprint":false},{"pmid":"10406843","id":"PMC_10406843","title":"Molecular cloning and characterization of cDNA coding for beta1, 2N-acetylglucosaminyltransferase I (GlcNAc-TI) from Nicotiana tabacum.","date":"1999","source":"Glycobiology","url":"https://pubmed.ncbi.nlm.nih.gov/10406843","citation_count":62,"is_preprint":false},{"pmid":"39264847","id":"PMC_39264847","title":"Lactate supports Treg function and immune balance via MGAT1 effects on N-glycosylation in the mitochondria.","date":"2024","source":"The Journal of clinical investigation","url":"https://pubmed.ncbi.nlm.nih.gov/39264847","citation_count":47,"is_preprint":false},{"pmid":"12373442","id":"PMC_12373442","title":"Kappa opioid antagonist effects of the novel kappa antagonist 5'-guanidinonaltrindole (GNTI) in an assay of schedule-controlled behavior in rhesus monkeys.","date":"2002","source":"Psychopharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/12373442","citation_count":44,"is_preprint":false},{"pmid":"22829770","id":"PMC_22829770","title":"Mgat1-dependent N-glycosylation of membrane components primes Drosophila melanogaster blood cells for the cellular encapsulation response.","date":"2012","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/22829770","citation_count":42,"is_preprint":false},{"pmid":"23777858","id":"PMC_23777858","title":"Engineering Chinese hamster ovary (CHO) cells for producing recombinant proteins with simple glycoforms by zinc-finger nuclease (ZFN)-mediated gene knockout of mannosyl (alpha-1,3-)-glycoprotein beta-1,2-N-acetylglucosaminyltransferase (Mgat1).","date":"2013","source":"Journal of biotechnology","url":"https://pubmed.ncbi.nlm.nih.gov/23777858","citation_count":40,"is_preprint":false},{"pmid":"9045817","id":"PMC_9045817","title":"Molecular genetic characterization of the Escherichia coli gntT gene of GntI, the main system for gluconate metabolism.","date":"1997","source":"Journal of bacteriology","url":"https://pubmed.ncbi.nlm.nih.gov/9045817","citation_count":39,"is_preprint":false},{"pmid":"19851299","id":"PMC_19851299","title":"Linkage and genome-wide association analysis of obesity-related phenotypes: association of weight with the MGAT1 gene.","date":"2009","source":"Obesity (Silver Spring, Md.)","url":"https://pubmed.ncbi.nlm.nih.gov/19851299","citation_count":39,"is_preprint":false},{"pmid":"38516892","id":"PMC_38516892","title":"GNTI-122: an autologous antigen-specific engineered Treg cell therapy for type 1 diabetes.","date":"2024","source":"JCI insight","url":"https://pubmed.ncbi.nlm.nih.gov/38516892","citation_count":37,"is_preprint":false},{"pmid":"8563140","id":"PMC_8563140","title":"Complex asparagine-linked oligosaccharides in Mgat1-null embryos.","date":"1995","source":"Glycobiology","url":"https://pubmed.ncbi.nlm.nih.gov/8563140","citation_count":35,"is_preprint":false},{"pmid":"30157178","id":"PMC_30157178","title":"CRISPR/Cas9 gene editing for the creation of an MGAT1-deficient CHO cell line to control HIV-1 vaccine glycosylation.","date":"2018","source":"PLoS biology","url":"https://pubmed.ncbi.nlm.nih.gov/30157178","citation_count":35,"is_preprint":false},{"pmid":"22957033","id":"PMC_22957033","title":"Suppression of cancer progression by MGAT1 shRNA knockdown.","date":"2012","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/22957033","citation_count":32,"is_preprint":false},{"pmid":"9363433","id":"PMC_9363433","title":"Complex N-glycans in Mgat1 null preimplantation embryos arise from maternal Mgat1 RNA.","date":"1997","source":"Glycobiology","url":"https://pubmed.ncbi.nlm.nih.gov/9363433","citation_count":31,"is_preprint":false},{"pmid":"9020882","id":"PMC_9020882","title":"Organization of the human beta-1,2-N-acetylglucosaminyltransferase I gene (MGAT1), which controls complex and hybrid N-glycan synthesis.","date":"1997","source":"The Biochemical journal","url":"https://pubmed.ncbi.nlm.nih.gov/9020882","citation_count":29,"is_preprint":false},{"pmid":"23351704","id":"PMC_23351704","title":"Hypomorphic MGAT5 polymorphisms promote multiple sclerosis cooperatively with MGAT1 and interleukin-2 and 7 receptor variants.","date":"2013","source":"Journal of neuroimmunology","url":"https://pubmed.ncbi.nlm.nih.gov/23351704","citation_count":29,"is_preprint":false},{"pmid":"20206280","id":"PMC_20206280","title":"Mgat1-dependent N-glycans are essential for the normal development of both vertebrate and invertebrate metazoans.","date":"2010","source":"Seminars in cell & developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/20206280","citation_count":29,"is_preprint":false},{"pmid":"20457894","id":"PMC_20457894","title":"Neuronal expression of Mgat1 rescues the shortened life span of Drosophila Mgat11 null mutants and increases life span.","date":"2010","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/20457894","citation_count":27,"is_preprint":false},{"pmid":"26928671","id":"PMC_26928671","title":"The G-protein biased partial κ opioid receptor agonist 6'-GNTI blocks hippocampal paroxysmal discharges without inducing aversion.","date":"2016","source":"British journal of pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/26928671","citation_count":26,"is_preprint":false},{"pmid":"20374941","id":"PMC_20374941","title":"Comparative genomics and proteomics of vertebrate diacylglycerol acyltransferase (DGAT), acyl CoA wax alcohol acyltransferase (AWAT) and monoacylglycerol acyltransferase (MGAT).","date":"2009","source":"Comparative biochemistry and physiology. Part D, Genomics & proteomics","url":"https://pubmed.ncbi.nlm.nih.gov/20374941","citation_count":25,"is_preprint":false},{"pmid":"23976952","id":"PMC_23976952","title":"Selective κ opioid antagonists nor-BNI, GNTI and JDTic have low affinities for non-opioid receptors and transporters.","date":"2013","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/23976952","citation_count":23,"is_preprint":false},{"pmid":"12618441","id":"PMC_12618441","title":"The activator of GntII genes for gluconate metabolism, GntH, exerts negative control of GntR-regulated GntI genes in Escherichia coli.","date":"2003","source":"Journal of bacteriology","url":"https://pubmed.ncbi.nlm.nih.gov/12618441","citation_count":23,"is_preprint":false},{"pmid":"26371870","id":"PMC_26371870","title":"GnT1IP-L specifically inhibits MGAT1 in the Golgi via its luminal domain.","date":"2015","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/26371870","citation_count":21,"is_preprint":false},{"pmid":"11467936","id":"PMC_11467936","title":"Independent Lec1A CHO glycosylation mutants arise from point mutations in N-acetylglucosaminyltransferase I that reduce affinity for both substrates. Molecular consequences based on the crystal structure of GlcNAc-TI.","date":"2001","source":"Biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/11467936","citation_count":21,"is_preprint":false},{"pmid":"36768334","id":"PMC_36768334","title":"Transmembrane Protein 68 Functions as an MGAT and DGAT Enzyme for Triacylglycerol Biosynthesis.","date":"2023","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/36768334","citation_count":19,"is_preprint":false},{"pmid":"28347400","id":"PMC_28347400","title":"Monoacylglycerol O-acyltransferase 1 (MGAT1) localizes to the ER and lipid droplets promoting triacylglycerol synthesis.","date":"2017","source":"BMB reports","url":"https://pubmed.ncbi.nlm.nih.gov/28347400","citation_count":19,"is_preprint":false},{"pmid":"30971450","id":"PMC_30971450","title":"The Golgi Localization of GnTI Requires a Polar Amino Acid Residue within Its Transmembrane Domain.","date":"2019","source":"Plant physiology","url":"https://pubmed.ncbi.nlm.nih.gov/30971450","citation_count":19,"is_preprint":false},{"pmid":"25623399","id":"PMC_25623399","title":"Expression and purification of soluble and stable ectodomain of natural killer cell receptor LLT1 through high-density transfection of suspension adapted HEK293S GnTI(-) cells.","date":"2015","source":"Protein expression and purification","url":"https://pubmed.ncbi.nlm.nih.gov/25623399","citation_count":19,"is_preprint":false},{"pmid":"39156890","id":"PMC_39156890","title":"Role of glycosylation-related gene MGAT1 in pancreatic ductal adenocarcinoma.","date":"2024","source":"Frontiers in immunology","url":"https://pubmed.ncbi.nlm.nih.gov/39156890","citation_count":18,"is_preprint":false},{"pmid":"29386567","id":"PMC_29386567","title":"MGAT1 and Complex N-Glycans Regulate ERK Signaling During Spermatogenesis.","date":"2018","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/29386567","citation_count":18,"is_preprint":false},{"pmid":"26742690","id":"PMC_26742690","title":"Molecular switches of the κ opioid receptor triggered by 6'-GNTI and 5'-GNTI.","date":"2016","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/26742690","citation_count":18,"is_preprint":false},{"pmid":"28737213","id":"PMC_28737213","title":"Identification of methylated GnTI-dependent N-glycans in Botryococcus brauni.","date":"2017","source":"The New phytologist","url":"https://pubmed.ncbi.nlm.nih.gov/28737213","citation_count":17,"is_preprint":false},{"pmid":"29310626","id":"PMC_29310626","title":"MGAT1 is a novel transcriptional target of Wnt/β-catenin signaling pathway.","date":"2018","source":"BMC cancer","url":"https://pubmed.ncbi.nlm.nih.gov/29310626","citation_count":15,"is_preprint":false},{"pmid":"24572742","id":"PMC_24572742","title":"Family studies of type 1 diabetes reveal additive and epistatic effects between MGAT1 and three other polymorphisms.","date":"2014","source":"Genes and immunity","url":"https://pubmed.ncbi.nlm.nih.gov/24572742","citation_count":15,"is_preprint":false},{"pmid":"17090929","id":"PMC_17090929","title":"In vivo expression of UDP-N-acetylglucosamine: Alpha-3-D-mannoside beta-1,2-N-acetylglucosaminyltransferase I (GnT-1) in Aspergillus oryzae and effects on the sugar chain of alpha-amylase.","date":"2006","source":"Bioscience, biotechnology, and biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/17090929","citation_count":14,"is_preprint":false},{"pmid":"21304485","id":"PMC_21304485","title":"Genetic variants near the MGAT1 gene are associated with body weight, BMI and fatty acid metabolism among adults and children.","date":"2011","source":"International journal of obesity (2005)","url":"https://pubmed.ncbi.nlm.nih.gov/21304485","citation_count":13,"is_preprint":false},{"pmid":"23859778","id":"PMC_23859778","title":"2-Substituted 4-hydroxybutanamides as potential inhibitors of γ-aminobutyric acid transporters mGAT1-mGAT4: synthesis and biological evaluation.","date":"2013","source":"Bioorganic & medicinal chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/23859778","citation_count":13,"is_preprint":false},{"pmid":"35491865","id":"PMC_35491865","title":"LINC00173 promotes Wilms' tumor progression through MGAT1-mediated MUC3A N-glycosylation.","date":"2022","source":"Cell cycle (Georgetown, Tex.)","url":"https://pubmed.ncbi.nlm.nih.gov/35491865","citation_count":12,"is_preprint":false},{"pmid":"25857788","id":"PMC_25857788","title":"Rapid and facile recombinant expression of bovine rhodopsin in HEK293S GnTI(-) cells using a PiggyBac inducible system.","date":"2015","source":"Methods in enzymology","url":"https://pubmed.ncbi.nlm.nih.gov/25857788","citation_count":12,"is_preprint":false},{"pmid":"16376105","id":"PMC_16376105","title":"Large-scale purification and characterization of human parathyroid hormone-1 receptor stably expressed in HEK293S GnTI- cells.","date":"2005","source":"Protein expression and purification","url":"https://pubmed.ncbi.nlm.nih.gov/16376105","citation_count":12,"is_preprint":false},{"pmid":"35758024","id":"PMC_35758024","title":"MicroRNA miR-331-3p suppresses osteosarcoma progression via the Bcl-2/Bax and Wnt/β-Catenin signaling pathways and the epithelial-mesenchymal transition by targeting N-acetylglucosaminyltransferase I (MGAT1).","date":"2022","source":"Bioengineered","url":"https://pubmed.ncbi.nlm.nih.gov/35758024","citation_count":12,"is_preprint":false},{"pmid":"28554385","id":"PMC_28554385","title":"Co-overexpression of Mgat1 and Mgat4 in CHO cells for production of highly sialylated albumin-erythropoietin.","date":"2017","source":"Enzyme and microbial technology","url":"https://pubmed.ncbi.nlm.nih.gov/28554385","citation_count":12,"is_preprint":false},{"pmid":"9871335","id":"PMC_9871335","title":"The gluconate high affinity transport of GntI in Escherichia coli involves a multicomponent complex system.","date":"1998","source":"Journal of basic microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/9871335","citation_count":12,"is_preprint":false},{"pmid":"14640558","id":"PMC_14640558","title":"Guanidino N-substituted and N,N-disubstituted derivatives of the kappa-opioid antagonist GNTI.","date":"2003","source":"Journal of medicinal chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/14640558","citation_count":10,"is_preprint":false},{"pmid":"40229283","id":"PMC_40229283","title":"MGAT1-Guided complex N-Glycans on CD73 regulate immune evasion in triple-negative breast cancer.","date":"2025","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/40229283","citation_count":9,"is_preprint":false},{"pmid":"17049114","id":"PMC_17049114","title":"Effect of GNTI, a kappa opioid receptor antagonist, on MK-801-induced hyperlocomotion and stereotypy in mice.","date":"2006","source":"Acta pharmacologica Sinica","url":"https://pubmed.ncbi.nlm.nih.gov/17049114","citation_count":9,"is_preprint":false},{"pmid":"28757467","id":"PMC_28757467","title":"High-level expression and purification of soluble form of human natural killer cell receptor NKR-P1 in HEK293S GnTI- cells.","date":"2017","source":"Protein expression and purification","url":"https://pubmed.ncbi.nlm.nih.gov/28757467","citation_count":8,"is_preprint":false},{"pmid":"28328319","id":"PMC_28328319","title":"Discovery of Human Intestinal MGAT Inhibitors Using High-Throughput Mass Spectrometry.","date":"2016","source":"SLAS discovery : advancing life sciences R & D","url":"https://pubmed.ncbi.nlm.nih.gov/28328319","citation_count":8,"is_preprint":false},{"pmid":"33165436","id":"PMC_33165436","title":"Circular RNA MGAT1 regulates cell proliferation and apoptosis in hypoxia-induced cardiomyocytes through miR-34a/YAP1 axis.","date":"2020","source":"International journal of clinical and experimental pathology","url":"https://pubmed.ncbi.nlm.nih.gov/33165436","citation_count":7,"is_preprint":false},{"pmid":"9252510","id":"PMC_9252510","title":"Ontogeny and location of HMG-CoA reductase, ACAT, and MGAT in human small intestine.","date":"1997","source":"The American journal of physiology","url":"https://pubmed.ncbi.nlm.nih.gov/9252510","citation_count":7,"is_preprint":false},{"pmid":"1359870","id":"PMC_1359870","title":"Mapping of the mouse bilirubin UDP-glucuronosyltransferase gene (Gnt-1) to chromosome 1 by restriction fragment length variations.","date":"1992","source":"Biochemical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/1359870","citation_count":7,"is_preprint":false},{"pmid":"32300591","id":"PMC_32300591","title":"Transgenic Rescue of Spermatogenesis in Males With Mgat1 Deleted in Germ Cells.","date":"2020","source":"Frontiers in cell and developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/32300591","citation_count":5,"is_preprint":false},{"pmid":"9926847","id":"PMC_9926847","title":"Nuclear proteins from liver and kidney bind a 37 bp sequence in the 5' upstream region of the mGAT1 gene.","date":"1998","source":"Neuroreport","url":"https://pubmed.ncbi.nlm.nih.gov/9926847","citation_count":4,"is_preprint":false},{"pmid":"38089803","id":"PMC_38089803","title":"The tobacco GNTI stem region harbors a strong motif for homomeric protein complex formation.","date":"2023","source":"Frontiers in plant science","url":"https://pubmed.ncbi.nlm.nih.gov/38089803","citation_count":3,"is_preprint":false},{"pmid":"32763972","id":"PMC_32763972","title":"Point mutations that inactivate MGAT4D-L, an inhibitor of MGAT1 and complex N-glycan synthesis.","date":"2020","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/32763972","citation_count":3,"is_preprint":false},{"pmid":"30344523","id":"PMC_30344523","title":"Development of a Stable MGAT1- CHO Cell Line to Produce Clade C gp120 With Improved Binding to Broadly Neutralizing Antibodies.","date":"2018","source":"Frontiers in immunology","url":"https://pubmed.ncbi.nlm.nih.gov/30344523","citation_count":3,"is_preprint":false},{"pmid":"31949680","id":"PMC_31949680","title":"Association between the MGAT1 rs634501 polymorphism and serum lipid traits in the Chinese Han and Maonan ethnic groups.","date":"2018","source":"International journal of clinical and experimental pathology","url":"https://pubmed.ncbi.nlm.nih.gov/31949680","citation_count":3,"is_preprint":false},{"pmid":"39083973","id":"PMC_39083973","title":"Subcellular imaging of MGAT1/MGAT2 homo- and heteromers in living cells using bioluminescence microscopy.","date":"2024","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/39083973","citation_count":2,"is_preprint":false},{"pmid":"39081317","id":"PMC_39081317","title":"Elucidating the multifaceted role of MGAT1 in hepatocellular carcinoma: integrative single-cell and spatial transcriptomics reveal novel therapeutic insights.","date":"2024","source":"Frontiers in immunology","url":"https://pubmed.ncbi.nlm.nih.gov/39081317","citation_count":2,"is_preprint":false},{"pmid":"19826906","id":"PMC_19826906","title":"Differential effects of human and plant N-acetylglucosaminyltransferase I (GnTI) in plants.","date":"2009","source":"Transgenic research","url":"https://pubmed.ncbi.nlm.nih.gov/19826906","citation_count":2,"is_preprint":false},{"pmid":"27871764","id":"PMC_27871764","title":"The rs4285184 polymorphism of the MGAT1 gene as a risk factor for obesity in the Mexican population.","date":"2016","source":"Medicina clinica","url":"https://pubmed.ncbi.nlm.nih.gov/27871764","citation_count":2,"is_preprint":false},{"pmid":"30983867","id":"PMC_30983867","title":"Identification of IFITM3 and MGAT1 as novel interaction partners of BRI3 by yeast two-hybrid screening.","date":"2018","source":"Turkish journal of biology = Turk biyoloji dergisi","url":"https://pubmed.ncbi.nlm.nih.gov/30983867","citation_count":1,"is_preprint":false},{"pmid":"40905205","id":"PMC_40905205","title":"CRISPR/Cas9-Mediated Knockouts of the ALG3 and GNTI in N. benthamiana and Their Application to Pharmaceutical Production.","date":"2025","source":"Plant biotechnology journal","url":"https://pubmed.ncbi.nlm.nih.gov/40905205","citation_count":1,"is_preprint":false},{"pmid":"41479910","id":"PMC_41479910","title":"MGAT1 knockout in human dendritic cells enhance CD8+ T cell activation.","date":"2025","source":"Frontiers in immunology","url":"https://pubmed.ncbi.nlm.nih.gov/41479910","citation_count":0,"is_preprint":false},{"pmid":"38557922","id":"PMC_38557922","title":"Determination, expression and characterization of an UDP-N-acetylglucosamine:α-1,3-D-mannoside β-1,2-N-acetylglucosaminyltransferase I (GnT-I) from the Pacific oyster, Crassostrea gigas.","date":"2024","source":"Glycoconjugate journal","url":"https://pubmed.ncbi.nlm.nih.gov/38557922","citation_count":0,"is_preprint":false},{"pmid":"12548803","id":"PMC_12548803","title":"[Study on the interaction between the 5' proximal region of mGAT-1 and nuclear proteins by the method of SPR].","date":"1999","source":"Shi yan sheng wu xue bao","url":"https://pubmed.ncbi.nlm.nih.gov/12548803","citation_count":0,"is_preprint":false},{"pmid":"11441462","id":"PMC_11441462","title":"Involvement of gntS in the control of GntI, the main system for gluconate metabolism in Escherichia coli.","date":"2001","source":"Journal of basic microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/11441462","citation_count":0,"is_preprint":false},{"pmid":"41744136","id":"PMC_41744136","title":"Exosomal circZNF638 promotes postmenopausal osteoporosis progression through MGAT1-mediated SMAD9 glycosylation.","date":"2026","source":"Connective tissue research","url":"https://pubmed.ncbi.nlm.nih.gov/41744136","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.10.03.680283","title":"Identification of key host genes for influenza A virus in avian cells using a genome-wide CRISPR-Cas9 screen","date":"2025-10-05","source":"bioRxiv","url":"https://doi.org/10.1101/2025.10.03.680283","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2025.07.18.25331799","title":"Profiling Neoadjuvant Therapy Response in Rectal Cancer Using Publicly Available Transcriptomic RNA-seq Datasets","date":"2025-07-23","source":"bioRxiv","url":"https://doi.org/10.1101/2025.07.18.25331799","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2025.02.15.638425","title":"Synthesis and Biological Evaluation of Nipecotic Acid Derivatives with Terminally Double-Substituted Allenic Spacers as mGAT4 Inhibitors","date":"2025-02-20","source":"bioRxiv","url":"https://doi.org/10.1101/2025.02.15.638425","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2024.10.29.620939","title":"EasyAb: A High-Throughput Workflow for Antibody-Based PTM Peptide Enrichment Method Coupled to Mass Spectrometry","date":"2024-11-01","source":"bioRxiv","url":"https://doi.org/10.1101/2024.10.29.620939","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":42931,"output_tokens":6839,"usd":0.115689,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":15779,"output_tokens":6459,"usd":0.120185,"stage2_stop_reason":"end_turn"},"total_usd":0.235874,"stage1_batch_id":"msgbatch_01BbTCMyrRPyhtEq6b1MdwCN","stage2_batch_id":"msgbatch_011dEed5bbxYvTAaQWKJevxu","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2002,\n      \"finding\": \"MGAT1 encodes a monoacylglycerol acyltransferase (MGAT) that catalyzes synthesis of diacylglycerol from oleoyl-CoA and monooleoylglycerol; expression of MGAT1 cDNA in insect cells markedly increased MGAT activity in cell membranes, and activity was proportional to MGAT1 protein level and dependent on substrate concentration.\",\n      \"method\": \"Heterologous expression in insect cells, membrane activity assay, substrate titration\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct in vitro enzymatic assay with substrate dose-response and protein-activity correlation, foundational cloning paper\",\n      \"pmids\": [\"12077311\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"The human MGAT1 gene (encoding GlcNAc-TI) is organized with at least two exons; the 5' flanking region of exon 1 contains Sp1 binding sites but no TATA or CCAAT boxes, consistent with a housekeeping gene. Transient transfection of a CAT reporter construct confirmed promoter activity in HeLa cells. Multiple transcription start sites give rise to two transcripts (~2.7–3.0 kb and 3.1 kb).\",\n      \"method\": \"Genomic cloning, transient transfection/CAT reporter assay, ribonuclease protection, primer extension, RT-PCR, Northern analysis\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (reporter assay, RNase protection, primer extension) in a single study defining gene structure and promoter activity\",\n      \"pmids\": [\"9020882\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1995,\n      \"finding\": \"Complex N-glycans detected in Mgat1-null preimplantation embryos (E3.5) by lectin histochemistry decline to undetectable levels by E7.5, demonstrating that maternally derived glycoproteins or transcripts sustain complex N-glycan presence early and that embryonically derived complex N-glycans become essential after E7.5.\",\n      \"method\": \"In situ RNA hybridization, lectin histochemistry on Mgat1-null embryos\",\n      \"journal\": \"Glycobiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct lectin histochemistry on null embryos with temporal staging, single lab\",\n      \"pmids\": [\"8563140\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"Complex N-glycans in Mgat1-null blastocysts arise from maternally derived Mgat1 mRNA present in oocytes; RT-PCR of identified null blastocysts confirmed wild-type Mgat1 RNA, and complex N-glycans (detected by L-PHA lectin binding) persisted until at least E4.5 but were absent in embryos from E5.5 onward.\",\n      \"method\": \"PCR genotyping of blastocysts, RT-PCR with restriction analysis, lectin binding (L-PHA)\",\n      \"journal\": \"Glycobiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genotype-confirmed embryos with molecular (RT-PCR) and lectin-based functional readout, single lab\",\n      \"pmids\": [\"9363433\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Two point mutations in GlcNAc-TI (MGAT1) found in independent Lec1A CHO mutants reduce affinity for both UDP-GlcNAc and Man5GlcNAc2Asn substrates: G634A converts Asp-212 in the conserved DXD motif (disrupting interactions with UDP-GlcNAc and Mn2+), and C907T converts Arg-303 to Trp (destabilizing a critical structural element). Site-directed mutagenesis reverting each mutation restored wild-type GlcNAc-TI activity.\",\n      \"method\": \"Sequencing of CHO mutants, site-directed mutagenesis, GlcNAc-TI activity assay, interpretation via crystal structure of rabbit GlcNAc-TI\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — mutagenesis with functional rescue combined with structural interpretation; active-site mechanism directly demonstrated\",\n      \"pmids\": [\"11467936\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Lec1 CHO cells lack GlcNAc-TI (MGAT1) activity due to mutations in the Mgat1 coding region; six independent lec1 mutations (insertions/transitions causing premature stop codons or frameshifts) were identified in the Mgat1 gene. Reversion of mutant cDNAs by site-directed mutagenesis restored wild-type lectin binding and GlcNAc-TI activity in Lec1 transfectants.\",\n      \"method\": \"Sequencing of genomic DNA/cDNA PCR products from mutant CHO lines, site-directed mutagenesis, GlcNAc-TI activity assay, lectin binding\",\n      \"journal\": \"Glycobiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct mutagenesis with functional rescue across six independent mutants; definitively establishes Mgat1 as the gene encoding GlcNAc-TI in CHO cells\",\n      \"pmids\": [\"12634323\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Conditional deletion of Mgat1 in oocytes (using ZP3Cre) causes a thinner zona pellucida lacking complex N-glycans, decreased fertility, fewer eggs and preimplantation embryos, and ~25% of resulting embryos are severely developmentally retarded. However, Mgat1-null embryos can still undergo fertilization, blastogenesis, and implantation, demonstrating that complex/hybrid N-glycans are required for oocyte developmental competence but not for fertilization or implantation per se.\",\n      \"method\": \"Conditional knockout (ZP3Cre), zona pellucida morphology/thickness measurement, lectin staining, embryo tracking, fertility assays\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional KO with multiple orthogonal phenotypic readouts (morphology, glycan staining, fertility, embryo development), replicated across multiple crosses\",\n      \"pmids\": [\"15509794\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"MGAT1 knockdown by shRNA in HeLa and PC-3 tumor cells reduces GlcNAc-TI transcript, enzyme activity, and branched N-glycans at the cell surface, inhibiting cell migration and invasion without altering proliferation. In orthotopic PC-3 xenograft mice, MGAT1 knockdown significantly decreased primary tumor growth and incidence of lung metastases. Swainsonine (α-mannosidase II inhibitor downstream of MGAT1) also inhibited invasion and was not additive with MGAT1 shRNA, indicating a common pathway.\",\n      \"method\": \"shRNA knockdown, GlcNAc-TI enzyme activity assay, cell surface lectin staining, migration/invasion assays, xenograft model, epistasis with swainsonine\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — loss-of-function with enzyme activity confirmation, epistasis experiment, in vivo xenograft validation, multiple orthogonal readouts\",\n      \"pmids\": [\"22957033\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Hepatic PPARγ2 directly regulates MGAT1 promoter activity; luciferase reporter assay, EMSA, and ChIP demonstrated direct PPARγ2 binding to the MGAT1 promoter. MGAT1 overexpression in hepatocytes enhanced triglyceride synthesis; liver-specific MGAT1 knockdown in high-fat-fed and ob/ob mice significantly reduced hepatic steatosis, weight gain, and improved glucose tolerance.\",\n      \"method\": \"Adenoviral PPARγ2 injection, microarray, luciferase promoter assay, EMSA, ChIP, MGAT1 overexpression/knockdown in hepatocytes and mice\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — multiple orthogonal methods (ChIP, EMSA, reporter assay, in vivo KD) in a single study definitively placing MGAT1 downstream of PPARγ2 in hepatic lipid metabolism\",\n      \"pmids\": [\"22869740\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"GnT1IP-L inhibits MGAT1 specifically in the Golgi via its luminal domain. Retention of GnT1IP-L in the ER markedly reduced inhibitory activity. Dynamic FRET and BiFC assays revealed homomeric GnT1IP-L interactions in the ER and heteromeric interactions with MGAT1 in the Golgi. GnT1IP-L did not generate FRET signals with MGAT2, MGAT3, MGAT4B, or MGAT5, demonstrating selectivity for MGAT1.\",\n      \"method\": \"ER-retention constructs, FRET, bimolecular fluorescence complementation (BiFC), GlcNAc-TI activity assay\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (FRET, BiFC, activity assay, subcellular targeting experiments) with selectivity controls against related enzymes\",\n      \"pmids\": [\"26371870\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Murine MGAT1 localizes to the endoplasmic reticulum under basal conditions and re-localizes to lipid droplets upon fatty acid enrichment, contributing to triacylglycerol synthesis and lipid droplet expansion. Both the N-terminal transmembrane domain and the catalytic HPHG motif are required for enzyme activity. MGAT1 interacts with DGAT2, synergistically increasing TAG biosynthesis and lipid droplet expansion.\",\n      \"method\": \"Fluorescent protein tagging and live-cell imaging, domain mutagenesis, co-immunoprecipitation with DGAT2, lipid accumulation assay\",\n      \"journal\": \"BMB reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization imaging with functional consequence, domain mutagenesis, and Co-IP; single lab\",\n      \"pmids\": [\"28347400\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Conditional deletion of Mgat1 in spermatogonia (Mgat1 cKO) causes loss of complex N-glycans, reduced EGFR and PDGFRA transcripts, and reduced ERK1/2 signaling in germ cells. Basigin (a germ cell glycoprotein and MGAT1 substrate) activated ERK1/2 in CHO cells but not in Lec1 CHO cells lacking MGAT1, placing MGAT1-dependent N-glycosylation of basigin upstream of ERK signaling in spermatogenesis.\",\n      \"method\": \"Conditional knockout, gene expression microarray, IPA/GSEA bioinformatics, Western blot for ERK1/2, CHO cell epistasis (Lec1 vs. wild-type) with basigin transfection\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — conditional KO with pathway analysis confirmed by cell-based epistasis experiment; single lab\",\n      \"pmids\": [\"29386567\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"MGAT1 is a transcriptional target of the Wnt/β-catenin signaling pathway; activation of Wnt/β-catenin (by LiCl, GSK-3β inhibitor, or mutant β-catenin overexpression) upregulates MGAT1 at mRNA and protein levels. β-catenin overexpression increased MGAT1 promoter activity in a luciferase assay. MGAT1 overexpression in Huh7 cells increased proliferation, migration, and tumor growth in SCID mice.\",\n      \"method\": \"Western blot, RT-qPCR, luciferase promoter assay, wound healing assay, XTT proliferation assay, xenograft in SCID mice\",\n      \"journal\": \"BMC cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (reporter assay, protein/mRNA quantitation, functional assays, in vivo) in a single study; single lab\",\n      \"pmids\": [\"29310626\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"MGAT1 must be expressed specifically in spermatogonia (not spermatocytes or spermatids) for normal spermatogenesis. Transgenic rescue with Stra8-Mgat1-HA (spermatogonia-specific) in Mgat1 cKO males restored normal testis morphology, N-glycan complement on basigin, and fertility; rescue with spermatocyte- or spermatid-specific transgenes did not.\",\n      \"method\": \"Conditional knockout rescue with cell-type-specific Mgat1 transgenes (Stra8-, Ldhc-, Prm1-promoters), MALDI imaging mass spectrometry of testis N-glycans, lectin histochemistry, fertility testing\",\n      \"journal\": \"Frontiers in cell and developmental biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — epistasis-by-rescue experiment with multiple transgene lines and orthogonal readouts (MALDI-IMS glycomics, lectin staining, fertility); definitively places MGAT1 requirement in spermatogonia\",\n      \"pmids\": [\"32300591\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Golgi localization of GnTI (MGAT1 ortholog in plants) requires a conserved glutamine residue within the transmembrane domain. Substitution of this Gln with other amino acids caused mislocalization to the vacuole and impaired N-glycan processing in vivo, suggesting the TMD interacts with a Golgi-resident adaptor or lipid environment mediating COPI-dependent retrograde transport.\",\n      \"method\": \"Site-directed mutagenesis of TMD, fluorescent fusion protein subcellular localization, N-glycan profiling in Arabidopsis and tobacco\",\n      \"journal\": \"Plant physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mutagenesis with functional localization and glycan processing readout; plant ortholog study with mechanistic insight applicable to MGAT1 TMD function\",\n      \"pmids\": [\"30971450\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"MGAT4D-L inhibits MGAT1 activity in mammalian and Drosophila S2 cells. Site-directed mutagenesis identified a five-amino-acid C-terminal motif (PSLFQ) in MGAT4D-L as essential for MGAT1 inhibition; deletion or Ala-substitution of PSLFQ inactivated inhibitory activity. Within PSLFQ, both Leu-395 and Phe-396 are independently essential. Inactive MGAT4D-L mutants still co-immunoprecipitated with MGAT1, indicating that physical interaction alone is insufficient for inhibition.\",\n      \"method\": \"Transfection in CHO/S2 cells, GNA lectin binding assay for MGAT1 substrate accumulation, site-directed mutagenesis, co-immunoprecipitation\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — systematic mutagenesis with functional assay and Co-IP; multiple residues tested; negative Co-IP control dissociates binding from inhibition\",\n      \"pmids\": [\"32763972\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"MGAT1 is translocated into mitochondria in human Tregs upon elevated intracellular lactate. The mechanism involves lactate-induced XBP1s activation promoting MGAT1 transcription, and direct interaction of lactate with the TOM70 import receptor facilitating MGAT1 mitochondrial translocation. Mitochondrial MGAT1 drives N-glycosylation of progranulin (GRN) and HYOU1, enhancing Treg oxidative phosphorylation and suppressive function.\",\n      \"method\": \"Mitochondrial isolation, sequencing, XBP1s transcription factor analysis, TOM70 interaction assay, N-glycosylation of GRN/HYOU1, Treg functional assays, xenogeneic GvHD mouse model\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mitochondrial fractionation combined with functional readouts and in vivo model; novel non-canonical localization finding, single lab\",\n      \"pmids\": [\"39264847\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"MGAT1 overexpression in triple-negative breast cancer leads to immune evasion by promoting CD73 membrane translocation. Mechanistically, MGAT1 adds N-acetylglucosamine to CD73, enabling CD73 dimerization required for loading onto VAMP3 and membrane fusion. THBS1 is identified as an upstream factor orchestrating the MGAT1–CD73–VAMP3–adenosine axis. A specific MGAT1 inhibitor (W-GTF01) blocking CD73 glycosylation sensitized refractory tumors to anti-PD-L1 therapy.\",\n      \"method\": \"MGAT1 overexpression/KO, Co-IP, CD73 glycosylation assay, VAMP3 interaction, spatial transcriptomics, preclinical TNBC mouse models with anti-PD-L1 combination\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mechanistic pathway established by Co-IP, glycosylation assay, and in vivo model with inhibitor validation; single lab, novel finding\",\n      \"pmids\": [\"40229283\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"MGAT1 homo- and heteromers with MGAT2 can be visualized in living cells; NanoBiT bioluminescence imaging demonstrated ER-to-Golgi transitions of MGAT1/MGAT2 homo- and heteromeric complexes, establishing that these glycosylation enzymes physically interact in both compartments.\",\n      \"method\": \"Split-luciferase complementation (NanoBiT), bioluminescence microscopy in live cells\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct PPI imaging with near-endogenous expression levels in living cells; single lab, single method\",\n      \"pmids\": [\"39083973\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"MGAT1 knockout in human dendritic cells (MUTZ-3 line) abolishes complex and hybrid N-glycan synthesis, upregulates NF-κB (NFKB1 mRNA elevated) and IFNB1, increases surface HLA-ABC, HLA-DR, and CD40 density, and markedly enhances CD8+ T cell activation and proliferation in vitro. This demonstrates that MGAT1-dependent complex/hybrid N-glycans negatively regulate DC immunostimulatory function.\",\n      \"method\": \"CRISPR/Cas9 KO of MGAT1 in MUTZ-3-derived DCs, flow cytometry (surface markers), allogeneic T cell activation assay, cytokine measurement, RT-qPCR\",\n      \"journal\": \"Frontiers in immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KO with defined cellular phenotype and molecular mechanism (NF-κB upregulation); single lab\",\n      \"pmids\": [\"41479910\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"MGAT1 stabilizes MUC3A protein by inducing N-glycosylation of MUC3A; knockdown of MGAT1 (downstream of lncRNA LINC00173 which stabilizes MGAT1 mRNA via HNRNPA2B1 recruitment) reduced MUC3A protein levels and inhibited Wilms' tumor cell invasion and promoted apoptosis in vitro and in vivo.\",\n      \"method\": \"RNA pull-down, RIP, dual-luciferase reporter, Western blot, N-glycosylation assay, functional cell and animal experiments\",\n      \"journal\": \"Cell cycle\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — N-glycosylation of a specific substrate (MUC3A) demonstrated with multiple molecular assays; single lab\",\n      \"pmids\": [\"35491865\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"MGAT1 was identified as a binding partner of BRI3 by yeast two-hybrid screening of a human liver cDNA library; interaction confirmed by cotransformation in yeast and co-immunoprecipitation from mammalian cell lines.\",\n      \"method\": \"Yeast two-hybrid, cotransformation, co-immunoprecipitation\",\n      \"journal\": \"Turkish journal of biology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, yeast two-hybrid plus Co-IP without further functional characterization of the interaction\",\n      \"pmids\": [\"30983867\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Neuronal expression of Mgat1 (GnT1) is required for normal locomotion and lifespan in Drosophila; CNS-specific knockdown phenocopies Mgat1 null locomotor and lifespan defects. Neuronal transgenic rescue of Mgat1 null mutants increased mean lifespan by 135% and correlated with increased GnT1 enzyme activity and resistance to oxidative stress.\",\n      \"method\": \"Tissue-specific RNAi (CNS knockdown), transgenic rescue with Mgat1 under neuronal promoter, GnT1 activity assay, lifespan analysis, oxidative stress assay\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — epistasis-by-rescue with direct enzyme activity measurement and multiple functional readouts; Drosophila ortholog study\",\n      \"pmids\": [\"20457894\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"In Drosophila, Mgat1-dependent N-glycosylation of immune cell membrane proteins is required for cellular encapsulation of parasitoid wasp eggs; loss-of-function mutations in Mgat1 and seven other N-glycosylation pathway genes led to defective capsule formation. Overexpression of Mgat1 conferred resistance against a wasp species that targets N-glycosylation as a virulence mechanism.\",\n      \"method\": \"Genetic mutant analysis, lectin staining of immune cell N-glycans, parasitoid wasp infection assay, Mgat1 overexpression\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function and gain-of-function in Drosophila immune cells with defined functional readout; Drosophila ortholog study\",\n      \"pmids\": [\"22829770\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"MGAT1 (GlcNAc-TI) is a medial Golgi-resident, type II transmembrane enzyme whose catalytic HPHG motif and DXD-containing active site transfer N-acetylglucosamine from UDP-GlcNAc onto Man5GlcNAc2-Asn, initiating the conversion of oligomannosyl to complex/hybrid N-glycans; it is transcriptionally regulated by PPARγ2 and Wnt/β-catenin, can be inhibited in the Golgi lumen by GnT1IP-L/MGAT4D-L via a PSLFQ C-terminal motif, localizes to the ER under basal conditions and to lipid droplets upon fatty acid loading where it interacts with DGAT2 to promote triacylglycerol synthesis, and is required in spermatogonia for ERK1/2 signaling during spermatogenesis; non-canonically, MGAT1 is also translocated into mitochondria in Tregs to promote N-glycosylation-dependent oxidative phosphorylation, and its glycosylation of substrates such as basigin, CD73, and MUC3A regulates ERK signaling, immune evasion, and tumor progression.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"MGAT1 encodes GlcNAc-TI, the medial-Golgi glycosyltransferase that initiates conversion of oligomannose to complex and hybrid N-glycans by transferring N-acetylglucosamine from UDP-GlcNAc onto Man5GlcNAc2-Asn; its activity depends on a DXD-containing active site, with Asp-212 coordinating UDP-GlcNAc and Mn2+ and Arg-303 stabilizing a critical structural element [#4, #5]. The enzyme is a type II Golgi protein whose N-terminal transmembrane domain and catalytic HPHG motif are both required for activity, and a conserved transmembrane glutamine residue mediates correct Golgi retention [#10, #14]. MGAT1 forms homomers and heteromers with MGAT2 that transit from the ER to the Golgi, and its output is selectively restrained in the Golgi lumen by the inhibitory proteins GnT1IP-L and MGAT4D-L, the latter acting through an essential C-terminal PSLFQ motif beyond mere physical binding [#9, #15, #18]. Loss of MGAT1-dependent complex N-glycans is developmentally essential: Mgat1-null embryos lose complex glycans after the depletion of maternally supplied transcript and die post-implantation, and complex glycans are required for oocyte developmental competence and, in spermatogonia specifically, for ERK1/2 signaling downstream of glycosylated basigin during spermatogenesis [#2, #3, #6, #11, #13]. Beyond glycan biosynthesis, MGAT1 is transcriptionally driven by hepatic PPARγ2 and by Wnt/β-catenin signaling and promotes triacylglycerol synthesis through relocalization to lipid droplets and interaction with DGAT2 [#8, #10, #12]. Through N-glycosylation of cell-surface substrates including basigin, CD73, and MUC3A, MGAT1 modulates tumor invasion, immune evasion, and dendritic-cell immunostimulatory function, and a non-canonical mitochondrial pool supports Treg oxidative phosphorylation [#7, #16, #17, #19, #20].\",\n  \"teleology\": [\n    {\n      \"year\": 1995,\n      \"claim\": \"Established that embryonically produced complex N-glycans become essential only after early post-implantation stages, defining the developmental window of MGAT1 dependency.\",\n      \"evidence\": \"In situ hybridization and lectin histochemistry on staged Mgat1-null embryos\",\n      \"pmids\": [\"8563140\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Did not identify which glycoprotein substrates are essential at E7.5\", \"Source of persisting early glycans not molecularly resolved in this study\"]\n    },\n    {\n      \"year\": 1997,\n      \"claim\": \"Defined the human MGAT1 gene structure and a TATA-less, Sp1-containing housekeeping promoter, providing the transcriptional framework for the gene.\",\n      \"evidence\": \"Genomic cloning with CAT reporter, RNase protection and primer extension in HeLa cells\",\n      \"pmids\": [\"9020882\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Did not identify regulatory transcription factors\", \"Functional significance of the two transcripts unresolved\"]\n    },\n    {\n      \"year\": 1997,\n      \"claim\": \"Showed that complex N-glycans in Mgat1-null blastocysts derive from maternal oocyte mRNA, explaining the delayed onset of the null phenotype.\",\n      \"evidence\": \"Genotyping and RT-PCR of null blastocysts with L-PHA lectin binding\",\n      \"pmids\": [\"9363433\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Did not address tissue-specific embryonic requirements\", \"Perdurance kinetics of maternal protein vs mRNA not separated\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Pinpointed active-site residues by mapping Lec1A CHO mutations to the DXD motif (Asp-212) and a structural Arg-303, directly establishing the catalytic mechanism.\",\n      \"evidence\": \"Sequencing of CHO mutants, site-directed reversion with activity rescue, interpreted via the rabbit enzyme crystal structure\",\n      \"pmids\": [\"11467936\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Human enzyme structure not solved here\", \"Catalytic transition-state chemistry not directly probed\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Definitively identified Mgat1 as the gene encoding GlcNAc-TI by showing six independent loss-of-function mutations in Lec1 CHO cells rescued by cDNA reversion.\",\n      \"evidence\": \"Sequencing of mutant CHO lines, site-directed mutagenesis, activity and lectin assays\",\n      \"pmids\": [\"12634323\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not address regulation or non-catalytic functions\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Demonstrated that MGAT1-dependent complex N-glycans are required for oocyte developmental competence but dispensable for fertilization and implantation, refining the in vivo requirement.\",\n      \"evidence\": \"ZP3Cre oocyte conditional knockout with zona pellucida morphology, lectin staining and fertility assays\",\n      \"pmids\": [\"15509794\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specific glycoprotein substrates of zona competence not identified\", \"Molecular cause of embryo retardation unresolved\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Showed a neuronal requirement for the Mgat1 ortholog in locomotion, lifespan, and oxidative-stress resistance, linking N-glycosylation to neuronal homeostasis.\",\n      \"evidence\": \"CNS-specific RNAi and neuronal transgenic rescue in Drosophila with enzyme activity and lifespan readouts\",\n      \"pmids\": [\"20457894\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Neuronal glycoprotein substrates not identified\", \"Mechanism linking glycans to oxidative-stress resistance unknown\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Connected MGAT1-generated branched N-glycans to tumor migration, invasion and metastasis through a pathway shared with downstream α-mannosidase II.\",\n      \"evidence\": \"shRNA knockdown in HeLa/PC-3, enzyme activity and lectin assays, invasion assays, orthotopic xenografts, swainsonine epistasis\",\n      \"pmids\": [\"22957033\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specific pro-invasion glycoprotein substrates not defined here\", \"Downstream signaling not mapped\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Placed MGAT1 downstream of hepatic PPARγ2 as a driver of triglyceride synthesis and steatosis, establishing a metabolic regulatory and functional role distinct from glycan branching.\",\n      \"evidence\": \"PPARγ2 ChIP/EMSA/luciferase, MGAT1 overexpression and liver-specific knockdown in high-fat and ob/ob mice\",\n      \"pmids\": [\"22869740\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Reconciliation of a glycosyltransferase with acyltransferase-driven TG synthesis not resolved\", \"Direct enzymatic mechanism of TG contribution unaddressed here\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Reported a monoacylglycerol acyltransferase activity for MGAT1, attributing diacylglycerol synthesis to the expressed protein.\",\n      \"evidence\": \"Heterologous expression in insect cells with membrane MGAT activity assay and substrate titration\",\n      \"pmids\": [\"12077311\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relationship between this acyltransferase activity and GlcNAc-transferase identity not reconciled\", \"Possible gene-symbol ambiguity not addressed in the assay\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Identified GnT1IP-L as a selective Golgi-luminal inhibitor of MGAT1, revealing a layer of compartment-specific regulation of glycan branching.\",\n      \"evidence\": \"ER-retention constructs, FRET and BiFC interaction imaging, activity assays with selectivity controls against MGAT2/3/4B/5\",\n      \"pmids\": [\"26371870\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of inhibition not resolved\", \"Physiological contexts of GnT1IP-L action not defined\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Showed MGAT1 relocalizes from ER to lipid droplets on fatty acid loading and synergizes with DGAT2 to expand triacylglycerol stores, supporting a direct lipid-metabolic function.\",\n      \"evidence\": \"Live-cell imaging, domain mutagenesis of TMD and HPHG motif, DGAT2 co-immunoprecipitation, lipid accumulation assays\",\n      \"pmids\": [\"28347400\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which a Golgi glycosyltransferase contributes to TAG synthesis unresolved\", \"Single lab\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Established MGAT1 as a Wnt/β-catenin transcriptional target promoting hepatocellular tumor growth, linking developmental signaling to MGAT1 expression.\",\n      \"evidence\": \"LiCl/GSK-3β-inhibitor/mutant β-catenin manipulation, luciferase promoter assay, proliferation/migration assays, SCID xenograft\",\n      \"pmids\": [\"29310626\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct β-catenin/TCF binding site not mapped\", \"Substrates driving the tumor phenotype not defined\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Demonstrated MGAT1-dependent N-glycosylation of basigin acts upstream of ERK1/2 signaling in germ cells, mechanistically connecting glycan branching to a signaling pathway.\",\n      \"evidence\": \"Spermatogonial conditional knockout with microarray/pathway analysis and CHO Lec1-vs-wildtype basigin epistasis\",\n      \"pmids\": [\"29386567\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct demonstration that basigin glycosylation alone restores ERK in vivo not shown\", \"Roles of reduced EGFR/PDGFRA glycosylation not separated\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Reported MGAT1 as a BRI3 binding partner, a candidate physical interaction lacking functional context.\",\n      \"evidence\": \"Yeast two-hybrid screen with cotransformation and co-immunoprecipitation\",\n      \"pmids\": [\"30983867\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Functional consequence of the interaction uncharacterized\", \"Single lab, no reciprocal in vivo validation\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Identified a conserved transmembrane glutamine as a Golgi-retention determinant for the GnTI ortholog, explaining how the enzyme is held in its biosynthetic compartment.\",\n      \"evidence\": \"TMD site-directed mutagenesis, fluorescent localization and N-glycan profiling in Arabidopsis and tobacco\",\n      \"pmids\": [\"30971450\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"The Golgi adaptor or lipid partner inferred but not identified\", \"Plant ortholog; mammalian retention machinery not directly tested\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Localized the essential MGAT1 requirement to spermatogonia by cell-type-specific transgenic rescue, defining where the enzyme must act for fertility.\",\n      \"evidence\": \"Conditional knockout rescue with Stra8/Ldhc/Prm1-promoter transgenes, MALDI imaging glycomics, lectin staining, fertility tests\",\n      \"pmids\": [\"32300591\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Full set of essential spermatogonial glycoproteins not enumerated\", \"Mechanistic link to later spermatid development unresolved\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Dissected MGAT4D-L inhibition of MGAT1 to a five-residue PSLFQ motif, showing physical binding is necessary but insufficient for inhibition.\",\n      \"evidence\": \"CHO/S2 transfection, GNA lectin substrate-accumulation assay, systematic mutagenesis, co-immunoprecipitation of inactive mutants\",\n      \"pmids\": [\"32763972\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural mechanism of how PSLFQ blocks catalysis unknown\", \"Physiological settings of MGAT4D-L inhibition undefined\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Showed MGAT1-mediated N-glycosylation stabilizes MUC3A to drive tumor invasion, identifying a specific oncogenic substrate.\",\n      \"evidence\": \"RNA pull-down/RIP for an upstream lncRNA axis, N-glycosylation and Western assays, cell and animal invasion/apoptosis experiments\",\n      \"pmids\": [\"35491865\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Glycosylation site on MUC3A not mapped\", \"Single lab\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Revealed a non-canonical mitochondrial MGAT1 pool that glycosylates GRN and HYOU1 to enhance Treg oxidative phosphorylation, expanding MGAT1 beyond the secretory pathway.\",\n      \"evidence\": \"Mitochondrial fractionation, XBP1s transcription analysis, TOM70 interaction, substrate glycosylation, Treg functional and GvHD models\",\n      \"pmids\": [\"39264847\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"How a UDP-GlcNAc-dependent enzyme functions in the mitochondrial environment unresolved\", \"Single lab; import mechanism mechanistically thin\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Visualized MGAT1 homomers and MGAT1–MGAT2 heteromers transitioning from ER to Golgi in living cells, establishing physical assembly of the branching enzymes.\",\n      \"evidence\": \"Split-luciferase (NanoBiT) bioluminescence imaging in live cells\",\n      \"pmids\": [\"39083973\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of heteromerization for catalysis not measured\", \"Single method, single lab\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Defined an MGAT1–CD73–VAMP3 axis in which CD73 glycosylation enables its dimerization and membrane delivery to drive tumor immune evasion, identifying a druggable mechanism.\",\n      \"evidence\": \"MGAT1 overexpression/KO, Co-IP, CD73 glycosylation and VAMP3 interaction assays, spatial transcriptomics, TNBC models with anti-PD-L1 and inhibitor W-GTF01\",\n      \"pmids\": [\"40229283\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Generalizability beyond TNBC not established\", \"Single lab\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Showed that loss of MGAT1-dependent complex/hybrid N-glycans enhances dendritic-cell immunostimulation via NF-κB and IFNB1, indicating these glycans normally restrain DC function.\",\n      \"evidence\": \"CRISPR/Cas9 MGAT1 KO in MUTZ-3 DCs, flow cytometry of HLA/CD40, allogeneic T-cell assays, cytokine and RT-qPCR analysis\",\n      \"pmids\": [\"41479910\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Specific DC glycoprotein substrates regulating NF-κB not identified\", \"Single lab, single cell line\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How MGAT1's reported acyltransferase/lipid-droplet and mitochondrial functions mechanistically relate to its canonical Golgi GlcNAc-transferase activity, and whether they reflect distinct activities of the same protein, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural or enzymatic reconciliation of dual glycosyltransferase/acyltransferase activities\", \"No unified model for substrate selection across compartments\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [4, 5, 7, 11, 17, 20]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [11, 17, 20]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [9, 14, 18]},\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [10, 18]},\n      {\"term_id\": \"GO:0005811\", \"supporting_discovery_ids\": [10]},\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [16]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [4, 5, 11, 17]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [8, 10]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [2, 6, 13]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [16, 17, 19]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"MGAT2\", \"DGAT2\", \"GnT1IP-L\", \"MGAT4D-L\", \"CD73\", \"VAMP3\", \"BRI3\", \"TOM70\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}