{"gene":"MGAT2","run_date":"2026-04-28T18:30:28","timeline":{"discoveries":[{"year":2003,"finding":"MGAT2 (monoacylglycerol acyltransferase 2) encodes an enzyme that catalyzes the acylation of monoacylglycerols to produce diacylglycerol; expression in insect or mammalian cells markedly increased MGAT activity in cell membranes, with activity proportional to MGAT2 protein level and substrate concentration.","method":"Heterologous expression in insect and mammalian cells, in vitro enzyme activity assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — in vitro enzymatic reconstitution replicated independently in two labs same year","pmids":["12621063","12576479"],"is_preprint":false},{"year":2003,"finding":"Mouse intestinal MGAT2 can catalyze acylation of rac-1-, sn-2-, and sn-3-monoacylglycerols with preference for unsaturated fatty acyl substrates, and also possesses an intrinsic acyl-CoA:diacylglycerol acyltransferase (DGAT) activity that can be distinguished from MGAT activity by detergent treatment (which abolishes DGAT but not MGAT activity).","method":"Expression in COS-7 cells and E. coli, in vitro enzyme assays with various substrates, detergent treatment","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — in vitro biochemical assay with mutagenic/chemical dissection of dual enzymatic activities, replicated across two papers","pmids":["12576479","12730219"],"is_preprint":false},{"year":2003,"finding":"MGAT2 enzyme activity is modulated by lipid cofactors: phosphatidylcholine, phosphatidylserine, and phosphatidic acid stimulate activity, while oleic acid and sphingosine inhibit it.","method":"In vitro enzyme assay with recombinant MGAT2 expressed in COS-7 cells, lipid cofactor supplementation","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 1 — in vitro assay, single lab","pmids":["12730219"],"is_preprint":false},{"year":1995,"finding":"Human MGAT2 (GlcNAc-T II) encodes a Golgi enzyme with a short cytoplasmic N-terminal domain, a 20-residue hydrophobic signal-anchor domain, and a 418-residue C-terminal catalytic domain; recombinant enzyme purified from baculovirus/Sf9 cells has specific activity ~20 µmol/min/mg and synthesizes the expected GlcNAc-linked product confirmed by NMR and mass spectrometry.","method":"Baculovirus expression, protein purification, 1H-NMR spectroscopy, mass spectrometry, FISH chromosome mapping","journal":"European journal of biochemistry","confidence":"High","confidence_rationale":"Tier 1 — purified recombinant enzyme with product identity confirmed by NMR and MS","pmids":["7635144"],"is_preprint":false},{"year":1996,"finding":"Point mutations (Ser→Phe and His→Arg) in the catalytic domain of MGAT2 (encoding GnT II) cause carbohydrate-deficient glycoprotein syndrome type II (CDG-IIa) by reducing enzyme protein expression and inactivating enzyme activity; heterozygotes show 33–68% reduction in GnT II activity.","method":"Patient mutation identification, baculovirus/insect cell expression, enzyme activity assay, restriction-endonuclease analysis of family members","journal":"American journal of human genetics","confidence":"High","confidence_rationale":"Tier 1–2 — active-site mutations functionally validated in expression system with enzyme activity measurement","pmids":["8808595"],"is_preprint":false},{"year":2002,"finding":"Homozygous deletion of mouse Mgat2 (GlcNAcT-II) eliminates GlcNAcT-II enzyme activity and complex N-glycan synthesis, resulting in severe gastrointestinal, hematologic, and osteogenic abnormalities and early post-natal lethality; a novel bisected hybrid N-glycan accumulates in mutant kidneys.","method":"Homozygous gene knockout mouse, enzyme activity assay, N-glycan structural analysis","journal":"Biochimica et biophysica acta","confidence":"High","confidence_rationale":"Tier 2 — clean KO with defined biochemical and phenotypic readouts, glycan structural analysis","pmids":["12417412"],"is_preprint":false},{"year":2014,"finding":"MGAT2 (monoacylglycerol acyltransferase) physically interacts with DGAT2 in the endoplasmic reticulum and on lipid droplets; this interaction depends on the two transmembrane domains of DGAT2 and results in increased triacylglycerol storage when both enzymes are co-expressed. DGAT2 translocates to lipid droplets upon 2-monoacylglycerol addition, indicating it utilizes MGAT2-derived diacylglycerol.","method":"Co-immunoprecipitation, in situ proximity ligation assay, chemical cross-linking (DSS), deletion mutagenesis, co-localization imaging, TG storage measurement","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP confirmed by proximity ligation and mutagenesis, multiple orthogonal methods in single study","pmids":["25164810"],"is_preprint":false},{"year":2009,"finding":"MGAT2 activity in enterocytes is required for triglyceride re-synthesis and chylomicron secretion, which drives postprandial GIP release; MGAT2 knockout mice fail to develop hypertriglyceridemia and have suppressed GIP response after oral triglyceride loading, whereas GLP-1 and PYY responses are preserved.","method":"Mgat2 knockout mouse, oral triglyceride loading, plasma lipid and gut hormone measurement","journal":"Biochemical and biophysical research communications","confidence":"High","confidence_rationale":"Tier 2 — genetic KO with specific biochemical and hormonal readouts placing MGAT2 upstream of GIP release","pmids":["19732742"],"is_preprint":false},{"year":2011,"finding":"MGAT2 deficiency increases energy expenditure by 10–15% independent of dietary fat level, and this mechanism is separate from fat absorption per se, as it is observed even on a fat-free diet and in genetically obese (Agouti) mice.","method":"Mogat2 knockout mouse, metabolic cage measurements (energy expenditure), cross to Agouti obese mice","journal":"Journal of lipid research","confidence":"High","confidence_rationale":"Tier 2 — clean KO with quantitative metabolic phenotyping across multiple dietary conditions and genetic backgrounds","pmids":["21734185"],"is_preprint":false},{"year":2013,"finding":"Myeloid-specific ablation of Mgat2 (GnT II) reduces multi-antennary N-glycans on antigen-presenting cells (APCs), impairing glycoantigen (polysaccharide) presentation and downstream T cell activation both in vitro and in vivo, without affecting protein antigen responses, TLR2 signaling, antigen uptake, or lymph node homing.","method":"Myeloid-specific conditional Mgat2 knockout mouse (LyzM-CRE), in vitro and in vivo T cell activation assays, glycan analysis","journal":"Glycobiology","confidence":"High","confidence_rationale":"Tier 2 — cell-type-specific KO with multiple functional readouts distinguishing glycoantigen vs protein antigen presentation","pmids":["24310166"],"is_preprint":false},{"year":1998,"finding":"The human MGAT2 gene promoter lacks a TATA box but contains a CCAAT box and multiple Sp1 consensus sites; deletion analysis identified a main promoter region between −636 and −553 bp relative to ATG, and the entire coding region is on a single exon.","method":"5'-RACE, RNase protection, chimeric promoter-CAT reporter transient transfection in HeLa cells","journal":"Glycoconjugate journal","confidence":"Medium","confidence_rationale":"Tier 2 — promoter deletion series with reporter assay, single lab","pmids":["9579808"],"is_preprint":false},{"year":2000,"finding":"Ets transcription factors (ets-1 and ets-2) transcriptionally stimulate the human MGAT2 (GnT II) promoter 2–4-fold through a specific Ets-binding site identified by mobility-shift assay and South-Western blot, but the promoter is not activated by src or neu oncogenes, distinguishing its regulation from GnT V.","method":"Co-transfection reporter assay (CAT), electrophoretic mobility-shift assay, South-Western blot","journal":"The Biochemical journal","confidence":"Medium","confidence_rationale":"Tier 2 — functional promoter assay combined with DNA-binding confirmation, single lab","pmids":["10749681"],"is_preprint":false},{"year":2024,"finding":"Conditional deletion of Mgat2 in spermatogonia (Stra8-iCre) blocks spermatogenesis prior to round spermatid formation, associated with increased AKT and ERK1/2 signaling in germ cells, distinct from the phenotype of Mgat1 deletion (which reduces ERK signaling), indicating that MGAT2-dependent complex N-glycans specifically regulate these signaling pathways during spermatogenesis.","method":"Conditional knockout mouse (Stra8-iCre), lectin binding (L-PHA, GSA-II), RNA-seq, Western blot for AKT and ERK1/2 phosphorylation, IPA pathway analysis","journal":"Frontiers in cell and developmental biology","confidence":"Medium","confidence_rationale":"Tier 2 — clean conditional KO with specific signaling readouts and comparison to Mgat1 KO, single lab","pmids":["39364139"],"is_preprint":false},{"year":2024,"finding":"MGAT1 and MGAT2 glycosyltransferases form both homodimers and heterodimers in living cells and undergo ER-to-Golgi transitions as homo- and heteromeric complexes, as directly visualized by bioluminescence microscopy using split-luciferase (NanoBiT) complementation.","method":"NanoBiT split-luciferase complementation assay, bioluminescence microscopy in living cells","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 3 — protein-protein interaction demonstrated by split-luciferase with subcellular imaging, single lab, no functional consequence tested","pmids":["39083973"],"is_preprint":false}],"current_model":"MGAT2 encodes two functionally distinct enzymes depending on context: (1) in the Golgi, it is UDP-GlcNAc:α-6-D-mannoside β-1,2-N-acetylglucosaminyltransferase II (GnT II), an essential enzyme for converting oligomannose to complex N-glycans, whose catalytic domain mutations cause CDG-IIa and whose N-glycan products regulate immune antigen presentation, spermatogenesis (via AKT/ERK signaling), and neurological development; and (2) in enterocyte endoplasmic reticulum, it is acyl-CoA:monoacylglycerol acyltransferase 2 (MGAT2), which catalyzes the first step in the monoacylglycerol pathway of triglyceride re-synthesis, physically interacts with DGAT2 through DGAT2's transmembrane domains to channel diacylglycerol for triacylglycerol synthesis, and controls dietary fat absorption, postprandial GIP secretion, and systemic energy expenditure."},"narrative":{"teleology":[{"year":1995,"claim":"Establishing that MGAT2 encodes a type II membrane glycosyltransferase (GnT II) with defined domain architecture and catalytic activity resolved the identity of the enzyme responsible for the key N-glycan branching step.","evidence":"Baculovirus expression and purification from Sf9 cells with product confirmed by NMR and mass spectrometry","pmids":["7635144"],"confidence":"High","gaps":["Substrate specificity determinants within the catalytic domain were not mapped","Oligomeric state of the enzyme in the Golgi was unknown"]},{"year":1996,"claim":"Identifying point mutations in GnT II that abolish enzyme activity in CDG-IIa patients established the gene as causative for this congenital disorder of glycosylation and defined critical catalytic-domain residues.","evidence":"Patient mutation identification with functional validation in baculovirus/insect cell expression system; family analysis by restriction endonuclease digestion","pmids":["8808595"],"confidence":"High","gaps":["Structural basis for how individual substitutions inactivate catalysis was not determined","Genotype-phenotype correlation across CDG-IIa spectrum was unexplored"]},{"year":1998,"claim":"Characterization of the MGAT2 promoter revealed a TATA-less, Sp1/CCAAT-driven architecture and later identified Ets-factor regulation, distinguishing its transcriptional control from that of GnT V.","evidence":"5'-RACE, RNase protection, promoter-CAT reporter deletion series in HeLa cells; Ets co-transfection and mobility-shift assays","pmids":["9579808","10749681"],"confidence":"Medium","gaps":["Tissue-specific regulation (e.g., intestine vs. lymphoid) was not addressed","In vivo relevance of Ets-mediated activation was not tested"]},{"year":2002,"claim":"Homozygous Mgat2 knockout demonstrated that GnT II is indispensable for complex N-glycan synthesis in vivo, with loss causing multi-organ developmental defects and neonatal lethality.","evidence":"Constitutive knockout mouse with enzyme activity assay and N-glycan structural analysis","pmids":["12417412"],"confidence":"High","gaps":["Cell-type-specific contributions to the lethal phenotype were undefined","Compensatory glycosylation pathways were not characterized"]},{"year":2003,"claim":"Cloning and biochemical characterization of MGAT2 as a monoacylglycerol acyltransferase established a second, metabolically distinct function: the enzyme acylates monoacylglycerols to diacylglycerols and possesses intrinsic DGAT activity separable by detergent treatment.","evidence":"Heterologous expression in insect cells, COS-7, and E. coli with in vitro activity assays using various acyl-CoA and MAG substrates","pmids":["12621063","12576479","12730219"],"confidence":"High","gaps":["Whether the glycosyltransferase (GnT II) and acyltransferase (MOGAT2) are truly the same gene product or distinct loci was initially confusing in the literature","Structural basis for dual MGAT/DGAT activity was not resolved"]},{"year":2009,"claim":"Demonstrating that enterocyte MGAT2 is required for efficient triglyceride re-synthesis and chylomicron secretion, which in turn drives postprandial GIP release, placed the enzyme at a critical control point in dietary fat absorption and incretin signaling.","evidence":"Mogat2 knockout mouse with oral triglyceride loading and plasma lipid/gut hormone measurements","pmids":["19732742"],"confidence":"High","gaps":["Whether MGAT2 loss alters enterocyte lipid droplet dynamics was not examined","Contribution of other MGAT isoforms to residual activity was not quantified"]},{"year":2011,"claim":"Finding that MGAT2-deficient mice have increased energy expenditure independent of fat malabsorption revealed an unexpected systemic metabolic role beyond intestinal lipid processing.","evidence":"Mogat2 knockout crossed to Agouti obese mice, metabolic cage calorimetry under multiple dietary conditions","pmids":["21734185"],"confidence":"High","gaps":["Tissue(s) responsible for increased energy expenditure were not identified","Molecular mechanism linking MGAT2 loss to elevated metabolic rate remains unknown"]},{"year":2013,"claim":"Myeloid-specific Mgat2 ablation showed that GnT II-dependent complex N-glycans on antigen-presenting cells are specifically required for glycoantigen presentation and T cell activation, separating this function from protein-antigen processing.","evidence":"LyzM-Cre conditional knockout with in vitro and in vivo T cell activation assays comparing glyco- vs. protein antigens","pmids":["24310166"],"confidence":"High","gaps":["Identity of the N-glycoprotein(s) on APCs whose glycosylation is critical for glycoantigen presentation was not determined","Whether this affects anti-bacterial immunity in vivo was not tested"]},{"year":2014,"claim":"Demonstrating a direct physical interaction between MGAT2 and DGAT2 dependent on DGAT2's transmembrane domains provided a channeling mechanism for diacylglycerol flux toward triacylglycerol synthesis in the ER and on lipid droplets.","evidence":"Co-immunoprecipitation, in situ proximity ligation assay, chemical cross-linking, deletion mutagenesis, and co-localization imaging","pmids":["25164810"],"confidence":"High","gaps":["Stoichiometry and structural architecture of the MGAT2–DGAT2 complex were not resolved","Whether the interaction is regulated by metabolic signals was not tested"]},{"year":2024,"claim":"Conditional deletion in spermatogonia revealed that MGAT2-generated complex N-glycans are required for spermatogenesis by restraining AKT/ERK signaling, while live-cell NanoBiT imaging demonstrated that MGAT2 (GnT II) forms homo- and heterodimers with MGAT1 during ER-to-Golgi transit.","evidence":"Stra8-iCre conditional knockout with signaling analysis; NanoBiT split-luciferase complementation with bioluminescence microscopy","pmids":["39364139","39083973"],"confidence":"Medium","gaps":["How complex N-glycans suppress AKT/ERK in germ cells is mechanistically unresolved","Functional consequence of MGAT1–MGAT2 heterodimerization on catalytic activity was not tested","Findings from single labs, not yet independently replicated"]},{"year":null,"claim":"No structural model of MGAT2 (GnT II) at atomic resolution exists, the mechanism linking MGAT2 loss to increased energy expenditure is unknown, and the functional significance of MGAT1–MGAT2 heterodimerization remains untested.","evidence":"","pmids":[],"confidence":"High","gaps":["Atomic structure of the catalytic domain has not been solved","Tissue-specific mediators of the energy expenditure phenotype are unidentified","Regulatory inputs that modulate MGAT2 enzymatic activity in vivo are poorly defined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[0,1,3,4,5]},{"term_id":"GO:0016853","term_label":"isomerase activity","supporting_discovery_ids":[1]}],"localization":[{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[3,5,13]},{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[6,13]},{"term_id":"GO:0005811","term_label":"lipid droplet","supporting_discovery_ids":[6]}],"pathway":[{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[0,1,6,7,8]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[3,4,5,9]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[9]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[4]}],"complexes":["MGAT2-DGAT2 complex","MGAT1-MGAT2 heterodimer"],"partners":["DGAT2","MGAT1"],"other_free_text":[]},"mechanistic_narrative":"MGAT2 encodes a Golgi-resident UDP-GlcNAc:α-6-D-mannoside β-1,2-N-acetylglucosaminyltransferase II (GnT II) that catalyzes a committed step in converting oligomannose N-glycans to complex-type N-glycans, a modification essential for gastrointestinal, hematologic, and skeletal development as well as immune glycoantigen presentation and spermatogenesis [PMID:7635144, PMID:12417412, PMID:24310166, PMID:39364139]. Loss-of-function mutations in the catalytic domain cause carbohydrate-deficient glycoprotein syndrome type II (CDG-IIa) [PMID:8808595]. The same gene symbol also designates acyl-CoA:monoacylglycerol acyltransferase 2 (MOGAT2), an ER-localized enzyme that acylates monoacylglycerols to diacylglycerols in the intestinal monoacylglycerol pathway of triglyceride re-synthesis; it physically interacts with DGAT2 via DGAT2's transmembrane domains to channel diacylglycerol toward triacylglycerol storage, and its enterocyte activity controls dietary fat absorption, postprandial GIP secretion, and systemic energy expenditure [PMID:12621063, PMID:25164810, PMID:19732742, PMID:21734185]."},"prefetch_data":{"uniprot":{"accession":"Q10469","full_name":"Alpha-1,6-mannosyl-glycoprotein 2-beta-N-acetylglucosaminyltransferase","aliases":["Beta-1,2-N-acetylglucosaminyltransferase II","GlcNAc-T II","GNT-II","Mannoside acetylglucosaminyltransferase 2","N-glycosyl-oligosaccharide-glycoprotein N-acetylglucosaminyltransferase II"],"length_aa":447,"mass_kda":51.5,"function":"Plays an essential role in protein N-glycosylation. Catalyzes the transfer of N-acetylglucosamine (GlcNAc) onto the free terminal mannose moiety in the core structure of the nascent N-linked glycan chain, giving rise to the second branch in complex glycans","subcellular_location":"Golgi apparatus membrane","url":"https://www.uniprot.org/uniprotkb/Q10469/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/MGAT2","classification":"Not Classified","n_dependent_lines":56,"n_total_lines":1208,"dependency_fraction":0.046357615894039736},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/MGAT2","total_profiled":1310},"omim":[{"mim_id":"610270","title":"MONOACYLGLYCEROL O-ACYLTRANSFERASE 2; MOGAT2","url":"https://www.omim.org/entry/610270"},{"mim_id":"602616","title":"ALPHA-1,6-@MANNOSYL-GLYCOPROTEIN BETA-1,2-N-ACETYLGLUCOSAMINYLTRANSFERASE; MGAT2","url":"https://www.omim.org/entry/602616"},{"mim_id":"212066","title":"CONGENITAL DISORDER OF GLYCOSYLATION, TYPE IIa; CDG2A","url":"https://www.omim.org/entry/212066"},{"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":"Supported","locations":[{"location":"Golgi apparatus","reliability":"Supported"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/MGAT2"},"hgnc":{"alias_symbol":["GNT-II"],"prev_symbol":[]},"alphafold":{"accession":"Q10469","domains":[{"cath_id":"3.90.550.10","chopping":"84-444","consensus_level":"high","plddt":95.0607,"start":84,"end":444}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q10469","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q10469-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q10469-F1-predicted_aligned_error_v6.png","plddt_mean":84.94},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=MGAT2","jax_strain_url":"https://www.jax.org/strain/search?query=MGAT2"},"sequence":{"accession":"Q10469","fasta_url":"https://rest.uniprot.org/uniprotkb/Q10469.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q10469/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q10469"}},"corpus_meta":[{"pmid":"12621063","id":"PMC_12621063","title":"MGAT2, a monoacylglycerol acyltransferase expressed in the small intestine.","date":"2003","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12621063","citation_count":161,"is_preprint":false},{"pmid":"8808595","id":"PMC_8808595","title":"Mutations in the MGAT2 gene controlling complex N-glycan synthesis cause carbohydrate-deficient glycoprotein syndrome type II, an autosomal recessive disease with defective brain development.","date":"1996","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/8808595","citation_count":129,"is_preprint":false},{"pmid":"12576479","id":"PMC_12576479","title":"Cloning and functional characterization of a mouse intestinal acyl-CoA:monoacylglycerol acyltransferase, MGAT2.","date":"2003","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12576479","citation_count":115,"is_preprint":false},{"pmid":"25164810","id":"PMC_25164810","title":"Diacylglycerol acyltransferase-2 (DGAT2) and monoacylglycerol acyltransferase-2 (MGAT2) interact to promote triacylglycerol synthesis.","date":"2014","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/25164810","citation_count":67,"is_preprint":false},{"pmid":"7635144","id":"PMC_7635144","title":"The human UDP-N-acetylglucosamine: alpha-6-D-mannoside-beta-1,2- N-acetylglucosaminyltransferase II gene (MGAT2). Cloning of genomic DNA, localization to chromosome 14q21, expression in insect cells and purification of the recombinant protein.","date":"1995","source":"European journal of biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/7635144","citation_count":64,"is_preprint":false},{"pmid":"19732742","id":"PMC_19732742","title":"Role of MGAT2 and DGAT1 in the release of gut peptides after triglyceride ingestion.","date":"2009","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/19732742","citation_count":55,"is_preprint":false},{"pmid":"12730219","id":"PMC_12730219","title":"Properties of the mouse intestinal acyl-CoA:monoacylglycerol acyltransferase, MGAT2.","date":"2003","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12730219","citation_count":52,"is_preprint":false},{"pmid":"21734185","id":"PMC_21734185","title":"Deficiency of MGAT2 increases energy expenditure without high-fat feeding and protects genetically obese mice from excessive weight gain.","date":"2011","source":"Journal of lipid research","url":"https://pubmed.ncbi.nlm.nih.gov/21734185","citation_count":38,"is_preprint":false},{"pmid":"36323235","id":"PMC_36323235","title":"MGAT2 inhibitor decreases liver fibrosis and inflammation in murine NASH models and reduces body weight in human adults with obesity.","date":"2022","source":"Cell metabolism","url":"https://pubmed.ncbi.nlm.nih.gov/36323235","citation_count":36,"is_preprint":false},{"pmid":"12417412","id":"PMC_12417412","title":"Mice with a homozygous deletion of the Mgat2 gene encoding UDP-N-acetylglucosamine:alpha-6-D-mannoside beta1,2-N-acetylglucosaminyltransferase II: a model for congenital disorder of glycosylation type IIa.","date":"2002","source":"Biochimica et biophysica acta","url":"https://pubmed.ncbi.nlm.nih.gov/12417412","citation_count":32,"is_preprint":false},{"pmid":"14652025","id":"PMC_14652025","title":"Evidence for alternative splicing and developmental regulation of the Drosophila melanogaster Mgat2 (N-acetylglucosaminyltransferase II) gene.","date":"2003","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/14652025","citation_count":17,"is_preprint":false},{"pmid":"29986142","id":"PMC_29986142","title":"Monoacylglycerol Acyltransferase 2 (MGAT2) Inhibitors for the Treatment of Metabolic Diseases and Nonalcoholic Steatohepatitis (NASH).","date":"2018","source":"Journal of medicinal chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/29986142","citation_count":16,"is_preprint":false},{"pmid":"25315695","id":"PMC_25315695","title":"MGAT2 deficiency and vertical sleeve gastrectomy have independent metabolic effects in the mouse.","date":"2014","source":"American journal of physiology. Endocrinology and metabolism","url":"https://pubmed.ncbi.nlm.nih.gov/25315695","citation_count":12,"is_preprint":false},{"pmid":"25598079","id":"PMC_25598079","title":"Cell-based assay of MGAT2-driven diacylglycerol synthesis for profiling inhibitors: use of a stable isotope-labeled substrate and high-resolution LC/MS.","date":"2015","source":"Journal of lipid research","url":"https://pubmed.ncbi.nlm.nih.gov/25598079","citation_count":10,"is_preprint":false},{"pmid":"33044030","id":"PMC_33044030","title":"Immune dysfunction in MGAT2-CDG: A clinical report and review of the literature.","date":"2020","source":"American journal of medical genetics. Part A","url":"https://pubmed.ncbi.nlm.nih.gov/33044030","citation_count":10,"is_preprint":false},{"pmid":"9579808","id":"PMC_9579808","title":"Transcriptional regulation of the human UDP-GlcNAc:alpha-6-D-mannoside beta-1-2-N-acetylglucosaminyltransferase II gene (MGAT2) which controls complex N-glycan synthesis.","date":"1998","source":"Glycoconjugate journal","url":"https://pubmed.ncbi.nlm.nih.gov/9579808","citation_count":9,"is_preprint":false},{"pmid":"10749681","id":"PMC_10749681","title":"Regulation of expression of the human beta-1,2-N-acetylglucosaminyltransferase II gene (MGAT2) by Ets transcription factors.","date":"2000","source":"The Biochemical journal","url":"https://pubmed.ncbi.nlm.nih.gov/10749681","citation_count":9,"is_preprint":false},{"pmid":"24310166","id":"PMC_24310166","title":"Mgat2 ablation in the myeloid lineage leads to defective glycoantigen T cell responses.","date":"2013","source":"Glycobiology","url":"https://pubmed.ncbi.nlm.nih.gov/24310166","citation_count":8,"is_preprint":false},{"pmid":"27146521","id":"PMC_27146521","title":"Dendritic cell-specific Mgat2 knockout mice show antigen presentation defects but reveal an unexpected CD11c expression pattern.","date":"2016","source":"Glycobiology","url":"https://pubmed.ncbi.nlm.nih.gov/27146521","citation_count":6,"is_preprint":false},{"pmid":"26210160","id":"PMC_26210160","title":"Identification of 2-[2-(4-tert-butylphenyl)ethyl]-N-(4-fluorophenyl)-1,2,3,4-tetrahydroisoquinoline-6-sulfonamide (29) as an orally available MGAT2 inhibitor.","date":"2015","source":"Bioorganic & medicinal chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/26210160","citation_count":5,"is_preprint":false},{"pmid":"39788365","id":"PMC_39788365","title":"Exploring the relationship between MGAT2 and glioblastoma: A Mendelian Randomization and bioinformatics approach.","date":"2025","source":"Brain research","url":"https://pubmed.ncbi.nlm.nih.gov/39788365","citation_count":2,"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":"26936050","id":"PMC_26936050","title":"Identification of 2-[2-(4-tert-Butylphenyl)ethyl]-N-[4-(3-cyclopentylpropyl)-2-fluorophenyl]-1,2,3,4-tetrahydroisoquinoline-6-sulfonamide as an Orally Active MGAT2 Inhibitor.","date":"2016","source":"Chemical & pharmaceutical bulletin","url":"https://pubmed.ncbi.nlm.nih.gov/26936050","citation_count":2,"is_preprint":false},{"pmid":"39364139","id":"PMC_39364139","title":"Deletion of Mgat2 in spermatogonia blocks spermatogenesis.","date":"2024","source":"Frontiers in cell and developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/39364139","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":13479,"output_tokens":3452,"usd":0.046108},"stage2":{"model":"claude-opus-4-6","input_tokens":6865,"output_tokens":2826,"usd":0.157463},"total_usd":0.203571,"stage1_batch_id":"msgbatch_01Mgbec4vM6c9vXht7JVJzss","stage2_batch_id":"msgbatch_01JkuuH5RB2BdJNsgnhjbC6s","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2003,\n      \"finding\": \"MGAT2 (monoacylglycerol acyltransferase 2) encodes an enzyme that catalyzes the acylation of monoacylglycerols to produce diacylglycerol; expression in insect or mammalian cells markedly increased MGAT activity in cell membranes, with activity proportional to MGAT2 protein level and substrate concentration.\",\n      \"method\": \"Heterologous expression in insect and mammalian cells, in vitro enzyme activity assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro enzymatic reconstitution replicated independently in two labs same year\",\n      \"pmids\": [\"12621063\", \"12576479\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Mouse intestinal MGAT2 can catalyze acylation of rac-1-, sn-2-, and sn-3-monoacylglycerols with preference for unsaturated fatty acyl substrates, and also possesses an intrinsic acyl-CoA:diacylglycerol acyltransferase (DGAT) activity that can be distinguished from MGAT activity by detergent treatment (which abolishes DGAT but not MGAT activity).\",\n      \"method\": \"Expression in COS-7 cells and E. coli, in vitro enzyme assays with various substrates, detergent treatment\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro biochemical assay with mutagenic/chemical dissection of dual enzymatic activities, replicated across two papers\",\n      \"pmids\": [\"12576479\", \"12730219\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"MGAT2 enzyme activity is modulated by lipid cofactors: phosphatidylcholine, phosphatidylserine, and phosphatidic acid stimulate activity, while oleic acid and sphingosine inhibit it.\",\n      \"method\": \"In vitro enzyme assay with recombinant MGAT2 expressed in COS-7 cells, lipid cofactor supplementation\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 — in vitro assay, single lab\",\n      \"pmids\": [\"12730219\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1995,\n      \"finding\": \"Human MGAT2 (GlcNAc-T II) encodes a Golgi enzyme with a short cytoplasmic N-terminal domain, a 20-residue hydrophobic signal-anchor domain, and a 418-residue C-terminal catalytic domain; recombinant enzyme purified from baculovirus/Sf9 cells has specific activity ~20 µmol/min/mg and synthesizes the expected GlcNAc-linked product confirmed by NMR and mass spectrometry.\",\n      \"method\": \"Baculovirus expression, protein purification, 1H-NMR spectroscopy, mass spectrometry, FISH chromosome mapping\",\n      \"journal\": \"European journal of biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — purified recombinant enzyme with product identity confirmed by NMR and MS\",\n      \"pmids\": [\"7635144\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"Point mutations (Ser→Phe and His→Arg) in the catalytic domain of MGAT2 (encoding GnT II) cause carbohydrate-deficient glycoprotein syndrome type II (CDG-IIa) by reducing enzyme protein expression and inactivating enzyme activity; heterozygotes show 33–68% reduction in GnT II activity.\",\n      \"method\": \"Patient mutation identification, baculovirus/insect cell expression, enzyme activity assay, restriction-endonuclease analysis of family members\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — active-site mutations functionally validated in expression system with enzyme activity measurement\",\n      \"pmids\": [\"8808595\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Homozygous deletion of mouse Mgat2 (GlcNAcT-II) eliminates GlcNAcT-II enzyme activity and complex N-glycan synthesis, resulting in severe gastrointestinal, hematologic, and osteogenic abnormalities and early post-natal lethality; a novel bisected hybrid N-glycan accumulates in mutant kidneys.\",\n      \"method\": \"Homozygous gene knockout mouse, enzyme activity assay, N-glycan structural analysis\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with defined biochemical and phenotypic readouts, glycan structural analysis\",\n      \"pmids\": [\"12417412\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"MGAT2 (monoacylglycerol acyltransferase) physically interacts with DGAT2 in the endoplasmic reticulum and on lipid droplets; this interaction depends on the two transmembrane domains of DGAT2 and results in increased triacylglycerol storage when both enzymes are co-expressed. DGAT2 translocates to lipid droplets upon 2-monoacylglycerol addition, indicating it utilizes MGAT2-derived diacylglycerol.\",\n      \"method\": \"Co-immunoprecipitation, in situ proximity ligation assay, chemical cross-linking (DSS), deletion mutagenesis, co-localization imaging, TG storage measurement\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP confirmed by proximity ligation and mutagenesis, multiple orthogonal methods in single study\",\n      \"pmids\": [\"25164810\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"MGAT2 activity in enterocytes is required for triglyceride re-synthesis and chylomicron secretion, which drives postprandial GIP release; MGAT2 knockout mice fail to develop hypertriglyceridemia and have suppressed GIP response after oral triglyceride loading, whereas GLP-1 and PYY responses are preserved.\",\n      \"method\": \"Mgat2 knockout mouse, oral triglyceride loading, plasma lipid and gut hormone measurement\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO with specific biochemical and hormonal readouts placing MGAT2 upstream of GIP release\",\n      \"pmids\": [\"19732742\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"MGAT2 deficiency increases energy expenditure by 10–15% independent of dietary fat level, and this mechanism is separate from fat absorption per se, as it is observed even on a fat-free diet and in genetically obese (Agouti) mice.\",\n      \"method\": \"Mogat2 knockout mouse, metabolic cage measurements (energy expenditure), cross to Agouti obese mice\",\n      \"journal\": \"Journal of lipid research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with quantitative metabolic phenotyping across multiple dietary conditions and genetic backgrounds\",\n      \"pmids\": [\"21734185\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Myeloid-specific ablation of Mgat2 (GnT II) reduces multi-antennary N-glycans on antigen-presenting cells (APCs), impairing glycoantigen (polysaccharide) presentation and downstream T cell activation both in vitro and in vivo, without affecting protein antigen responses, TLR2 signaling, antigen uptake, or lymph node homing.\",\n      \"method\": \"Myeloid-specific conditional Mgat2 knockout mouse (LyzM-CRE), in vitro and in vivo T cell activation assays, glycan analysis\",\n      \"journal\": \"Glycobiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — cell-type-specific KO with multiple functional readouts distinguishing glycoantigen vs protein antigen presentation\",\n      \"pmids\": [\"24310166\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"The human MGAT2 gene promoter lacks a TATA box but contains a CCAAT box and multiple Sp1 consensus sites; deletion analysis identified a main promoter region between −636 and −553 bp relative to ATG, and the entire coding region is on a single exon.\",\n      \"method\": \"5'-RACE, RNase protection, chimeric promoter-CAT reporter transient transfection in HeLa cells\",\n      \"journal\": \"Glycoconjugate journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — promoter deletion series with reporter assay, single lab\",\n      \"pmids\": [\"9579808\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Ets transcription factors (ets-1 and ets-2) transcriptionally stimulate the human MGAT2 (GnT II) promoter 2–4-fold through a specific Ets-binding site identified by mobility-shift assay and South-Western blot, but the promoter is not activated by src or neu oncogenes, distinguishing its regulation from GnT V.\",\n      \"method\": \"Co-transfection reporter assay (CAT), electrophoretic mobility-shift assay, South-Western blot\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — functional promoter assay combined with DNA-binding confirmation, single lab\",\n      \"pmids\": [\"10749681\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Conditional deletion of Mgat2 in spermatogonia (Stra8-iCre) blocks spermatogenesis prior to round spermatid formation, associated with increased AKT and ERK1/2 signaling in germ cells, distinct from the phenotype of Mgat1 deletion (which reduces ERK signaling), indicating that MGAT2-dependent complex N-glycans specifically regulate these signaling pathways during spermatogenesis.\",\n      \"method\": \"Conditional knockout mouse (Stra8-iCre), lectin binding (L-PHA, GSA-II), RNA-seq, Western blot for AKT and ERK1/2 phosphorylation, IPA pathway analysis\",\n      \"journal\": \"Frontiers in cell and developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean conditional KO with specific signaling readouts and comparison to Mgat1 KO, single lab\",\n      \"pmids\": [\"39364139\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"MGAT1 and MGAT2 glycosyltransferases form both homodimers and heterodimers in living cells and undergo ER-to-Golgi transitions as homo- and heteromeric complexes, as directly visualized by bioluminescence microscopy using split-luciferase (NanoBiT) complementation.\",\n      \"method\": \"NanoBiT split-luciferase complementation assay, bioluminescence microscopy in living cells\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — protein-protein interaction demonstrated by split-luciferase with subcellular imaging, single lab, no functional consequence tested\",\n      \"pmids\": [\"39083973\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"MGAT2 encodes two functionally distinct enzymes depending on context: (1) in the Golgi, it is UDP-GlcNAc:α-6-D-mannoside β-1,2-N-acetylglucosaminyltransferase II (GnT II), an essential enzyme for converting oligomannose to complex N-glycans, whose catalytic domain mutations cause CDG-IIa and whose N-glycan products regulate immune antigen presentation, spermatogenesis (via AKT/ERK signaling), and neurological development; and (2) in enterocyte endoplasmic reticulum, it is acyl-CoA:monoacylglycerol acyltransferase 2 (MGAT2), which catalyzes the first step in the monoacylglycerol pathway of triglyceride re-synthesis, physically interacts with DGAT2 through DGAT2's transmembrane domains to channel diacylglycerol for triacylglycerol synthesis, and controls dietary fat absorption, postprandial GIP secretion, and systemic energy expenditure.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"MGAT2 encodes a Golgi-resident UDP-GlcNAc:α-6-D-mannoside β-1,2-N-acetylglucosaminyltransferase II (GnT II) that catalyzes a committed step in converting oligomannose N-glycans to complex-type N-glycans, a modification essential for gastrointestinal, hematologic, and skeletal development as well as immune glycoantigen presentation and spermatogenesis [PMID:7635144, PMID:12417412, PMID:24310166, PMID:39364139]. Loss-of-function mutations in the catalytic domain cause carbohydrate-deficient glycoprotein syndrome type II (CDG-IIa) [PMID:8808595]. The same gene symbol also designates acyl-CoA:monoacylglycerol acyltransferase 2 (MOGAT2), an ER-localized enzyme that acylates monoacylglycerols to diacylglycerols in the intestinal monoacylglycerol pathway of triglyceride re-synthesis; it physically interacts with DGAT2 via DGAT2's transmembrane domains to channel diacylglycerol toward triacylglycerol storage, and its enterocyte activity controls dietary fat absorption, postprandial GIP secretion, and systemic energy expenditure [PMID:12621063, PMID:25164810, PMID:19732742, PMID:21734185].\",\n  \"teleology\": [\n    {\n      \"year\": 1995,\n      \"claim\": \"Establishing that MGAT2 encodes a type II membrane glycosyltransferase (GnT II) with defined domain architecture and catalytic activity resolved the identity of the enzyme responsible for the key N-glycan branching step.\",\n      \"evidence\": \"Baculovirus expression and purification from Sf9 cells with product confirmed by NMR and mass spectrometry\",\n      \"pmids\": [\"7635144\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Substrate specificity determinants within the catalytic domain were not mapped\", \"Oligomeric state of the enzyme in the Golgi was unknown\"]\n    },\n    {\n      \"year\": 1996,\n      \"claim\": \"Identifying point mutations in GnT II that abolish enzyme activity in CDG-IIa patients established the gene as causative for this congenital disorder of glycosylation and defined critical catalytic-domain residues.\",\n      \"evidence\": \"Patient mutation identification with functional validation in baculovirus/insect cell expression system; family analysis by restriction endonuclease digestion\",\n      \"pmids\": [\"8808595\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis for how individual substitutions inactivate catalysis was not determined\", \"Genotype-phenotype correlation across CDG-IIa spectrum was unexplored\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Characterization of the MGAT2 promoter revealed a TATA-less, Sp1/CCAAT-driven architecture and later identified Ets-factor regulation, distinguishing its transcriptional control from that of GnT V.\",\n      \"evidence\": \"5'-RACE, RNase protection, promoter-CAT reporter deletion series in HeLa cells; Ets co-transfection and mobility-shift assays\",\n      \"pmids\": [\"9579808\", \"10749681\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Tissue-specific regulation (e.g., intestine vs. lymphoid) was not addressed\", \"In vivo relevance of Ets-mediated activation was not tested\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Homozygous Mgat2 knockout demonstrated that GnT II is indispensable for complex N-glycan synthesis in vivo, with loss causing multi-organ developmental defects and neonatal lethality.\",\n      \"evidence\": \"Constitutive knockout mouse with enzyme activity assay and N-glycan structural analysis\",\n      \"pmids\": [\"12417412\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Cell-type-specific contributions to the lethal phenotype were undefined\", \"Compensatory glycosylation pathways were not characterized\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Cloning and biochemical characterization of MGAT2 as a monoacylglycerol acyltransferase established a second, metabolically distinct function: the enzyme acylates monoacylglycerols to diacylglycerols and possesses intrinsic DGAT activity separable by detergent treatment.\",\n      \"evidence\": \"Heterologous expression in insect cells, COS-7, and E. coli with in vitro activity assays using various acyl-CoA and MAG substrates\",\n      \"pmids\": [\"12621063\", \"12576479\", \"12730219\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether the glycosyltransferase (GnT II) and acyltransferase (MOGAT2) are truly the same gene product or distinct loci was initially confusing in the literature\", \"Structural basis for dual MGAT/DGAT activity was not resolved\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Demonstrating that enterocyte MGAT2 is required for efficient triglyceride re-synthesis and chylomicron secretion, which in turn drives postprandial GIP release, placed the enzyme at a critical control point in dietary fat absorption and incretin signaling.\",\n      \"evidence\": \"Mogat2 knockout mouse with oral triglyceride loading and plasma lipid/gut hormone measurements\",\n      \"pmids\": [\"19732742\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether MGAT2 loss alters enterocyte lipid droplet dynamics was not examined\", \"Contribution of other MGAT isoforms to residual activity was not quantified\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Finding that MGAT2-deficient mice have increased energy expenditure independent of fat malabsorption revealed an unexpected systemic metabolic role beyond intestinal lipid processing.\",\n      \"evidence\": \"Mogat2 knockout crossed to Agouti obese mice, metabolic cage calorimetry under multiple dietary conditions\",\n      \"pmids\": [\"21734185\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Tissue(s) responsible for increased energy expenditure were not identified\", \"Molecular mechanism linking MGAT2 loss to elevated metabolic rate remains unknown\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Myeloid-specific Mgat2 ablation showed that GnT II-dependent complex N-glycans on antigen-presenting cells are specifically required for glycoantigen presentation and T cell activation, separating this function from protein-antigen processing.\",\n      \"evidence\": \"LyzM-Cre conditional knockout with in vitro and in vivo T cell activation assays comparing glyco- vs. protein antigens\",\n      \"pmids\": [\"24310166\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the N-glycoprotein(s) on APCs whose glycosylation is critical for glycoantigen presentation was not determined\", \"Whether this affects anti-bacterial immunity in vivo was not tested\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Demonstrating a direct physical interaction between MGAT2 and DGAT2 dependent on DGAT2's transmembrane domains provided a channeling mechanism for diacylglycerol flux toward triacylglycerol synthesis in the ER and on lipid droplets.\",\n      \"evidence\": \"Co-immunoprecipitation, in situ proximity ligation assay, chemical cross-linking, deletion mutagenesis, and co-localization imaging\",\n      \"pmids\": [\"25164810\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stoichiometry and structural architecture of the MGAT2–DGAT2 complex were not resolved\", \"Whether the interaction is regulated by metabolic signals was not tested\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Conditional deletion in spermatogonia revealed that MGAT2-generated complex N-glycans are required for spermatogenesis by restraining AKT/ERK signaling, while live-cell NanoBiT imaging demonstrated that MGAT2 (GnT II) forms homo- and heterodimers with MGAT1 during ER-to-Golgi transit.\",\n      \"evidence\": \"Stra8-iCre conditional knockout with signaling analysis; NanoBiT split-luciferase complementation with bioluminescence microscopy\",\n      \"pmids\": [\"39364139\", \"39083973\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"How complex N-glycans suppress AKT/ERK in germ cells is mechanistically unresolved\", \"Functional consequence of MGAT1–MGAT2 heterodimerization on catalytic activity was not tested\", \"Findings from single labs, not yet independently replicated\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"No structural model of MGAT2 (GnT II) at atomic resolution exists, the mechanism linking MGAT2 loss to increased energy expenditure is unknown, and the functional significance of MGAT1–MGAT2 heterodimerization remains untested.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Atomic structure of the catalytic domain has not been solved\", \"Tissue-specific mediators of the energy expenditure phenotype are unidentified\", \"Regulatory inputs that modulate MGAT2 enzymatic activity in vivo are poorly defined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [0, 1, 3, 4, 5]},\n      {\"term_id\": \"GO:0016853\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [3, 5, 13]},\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [6, 13]},\n      {\"term_id\": \"GO:0005811\", \"supporting_discovery_ids\": [6]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [0, 1, 6, 7, 8]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [3, 4, 5, 9]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [9]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"complexes\": [\n      \"MGAT2-DGAT2 complex\",\n      \"MGAT1-MGAT2 heterodimer\"\n    ],\n    \"partners\": [\n      \"DGAT2\",\n      \"MGAT1\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}