DGAT1 (TAG1) is the acyl-CoA:diacylglycerol acyltransferase 1 of Arabidopsis, a multi-pass endoplasmic-reticulum membrane enzyme of the membrane-bound O-acyltransferase (MBOAT) family. It catalyzes the terminal, committed step of the acyl-CoA-dependent (Kennedy) pathway of triacylglycerol (TAG) assembly, transferring an acyl group from acyl-CoA to the sn-3 position of diacylglycerol to form TAG. It is the major microsomal DGAT activity in developing seeds and pollen and a principal determinant of seed-oil content; it acts partly redundantly with the acyl-CoA-independent enzyme PDAT1, so that strong TAG depletion and reproductive defects arise mainly when both routes are impaired. While its primary site is the ER, during leaf senescence DGAT1 is also associated with chloroplast envelope and thylakoid membranes, where it forms plastoglobular TAG from fatty acids recycled from thylakoid galactolipids.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005789 endoplasmic reticulum membrane | IBA GO_REF:0000033 | ACCEPT | Summary: Correct core localization. DGAT1 is an ER (microsomal) membrane enzyme; the ER is the functional site of TAG assembly. Consistent with experimental microsomal DGAT activity. |
| GO:0004144 diacylglycerol O-acyltransferase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Core molecular function, also supported by extensive experimental evidence (EXP/IDA/IMP below). DGAT1 transfers an acyl group from acyl-CoA to diacylglycerol to form TAG. |
| GO:0005789 endoplasmic reticulum membrane | IEA GO_REF:0000044 | ACCEPT | Summary: Correct core localization (ER membrane), consistent with the IBA annotation and with microsomal DGAT assays. |
| GO:0019432 triglyceride biosynthetic process | IEA GO_REF:0000120 | ACCEPT | Summary: Core biological process, also supported experimentally (IDA/IMP/TAS below). DGAT1 catalyzes the terminal step of TAG biosynthesis. |
| GO:0031969 chloroplast membrane | IEA GO_REF:0000044 | KEEP AS NON CORE | Summary: Retained as a non-core localization. This electronic UniProt subcellular-location annotation reflects the experimentally documented association of DGAT1 with chloroplast (envelope/thylakoid) membranes during leaf senescence, where it synthesizes plastoglobular TAG from recycled thylakoid galactolipid fatty acids (PMID:12177474). It is a genuine secondary localization, subordinate to the primary ER site of seed-oil TAG synthesis. Supporting Evidence: PMID:12177474 DGAT1 protein in senescing leaves was found to be associated with chloroplast membranes |
| GO:0004144 diacylglycerol O-acyltransferase activity | EXP PMID:11171171 Expression and characterization of diacylglycerol acyltransf... | ACCEPT | Summary: Core molecular function with direct experimental support for DGAT1 diacylglycerol acyltransferase activity. [PMID:11171171] Supporting Evidence: PMID:11171171 The expressed protein catalysed the synthesis of [(14)C]triacylglycerol from [(14)C]diacylglycerol and oleoyl-CoA. |
| GO:0005634 nucleus | ISM GO_REF:0000122 | REMOVE | Summary: Spurious computational (AtSubP sequence-model) prediction that contradicts the established ER membrane localization. DGAT1 is a multi-pass ER membrane protein; there is no evidence for nuclear localization. |
| GO:0005515 protein binding | IPI PMID:26586834 Identification of Arabidopsis GPAT9 (At5g60620) as an Essent... | KEEP AS NON CORE | Summary: Uninformative molecular-function term (per curation guidance, protein binding does not convey a specific function). The original_reference (PMID:26586834) is primarily about GPAT9, in which DGAT1 appears as an interaction partner. The interaction is experimental, so it is retained as non-core rather than removed; a specific partner and functional consequence would be needed to make it informative. |
| GO:0005811 lipid droplet | IDA PMID:24663078 Function and localization of the Arabidopsis thaliana diacyl... | KEEP AS NON CORE | Summary: Lipid-droplet association is consistent with TAG synthesis at the ER-lipid droplet interface. Retained as a non-core localization relative to the primary ER membrane site of catalysis. Note the original_reference (PMID:24663078) is primarily a study of the paralog DGAT2; the curator (TAIR) may have had DGAT1 data, but this specific evidence is not verified here. |
| GO:0019432 triglyceride biosynthetic process | IDA PMID:23770095 AtDGAT2 is a functional acyl-CoA:diacylglycerol acyltransfer... | ACCEPT | Summary: TAG biosynthesis is the core biological process of DGAT1 and is well established. Note the original_reference (PMID:23770095) is primarily about the paralog AtDGAT2 (with DGAT1 used for comparison); this specific reference is not independently verified here, but the TAG-biosynthesis role of DGAT1 is supported by the many DGAT-activity and tag1-mutant references in this review. |
| GO:0016020 membrane | IDA PMID:22233193 Triacylglycerol synthesis by PDAT1 in the absence of DGAT1 a... | ACCEPT | Summary: Correct but general. DGAT1 is an integral membrane protein; the informative localizations are the ER membrane (primary) and chloroplast membranes (senescence). The original_reference (PMID:22233193) is primarily a PDAT1/LPCAT2 study; the membrane-association of DGAT1 is independently documented. Supporting Evidence: PMID:12177474 Second, DGAT1 protein in senescing leaves was found to be associated with chloroplast membranes. |
| GO:0010029 regulation of seed germination | IMP PMID:10580283 The TAG1 locus of Arabidopsis encodes for a diacylglycerol a... | KEEP AS NON CORE | Summary: Pleiotropic/downstream phenotype of altered seed oil reserves, not DGAT1's molecular function. Retained as non-core. [PMID:10580283] |
| GO:0010030 positive regulation of seed germination | IMP PMID:10580283 The TAG1 locus of Arabidopsis encodes for a diacylglycerol a... | KEEP AS NON CORE | Summary: As above, a downstream consequence of seed oil storage on germination vigor rather than a core function. Retained as non-core. [PMID:10580283] |
| GO:0004144 diacylglycerol O-acyltransferase activity | ISS PMID:10571850 The Arabidopsis thaliana TAG1 mutant has a mutation in a dia... | ACCEPT | Summary: Core molecular function (sequence/similarity support), consistent with the experimental DGAT activity annotations. |
| GO:0004144 diacylglycerol O-acyltransferase activity | IDA PMID:10571850 The Arabidopsis thaliana TAG1 mutant has a mutation in a dia... | ACCEPT | Summary: Core molecular function with direct assay support. [PMID:10571850] Supporting Evidence: PMID:10571850 The Arabidopsis thaliana TAG1 mutant has a mutation in a diacylglycerol acyltransferase gene. |
| GO:0004144 diacylglycerol O-acyltransferase activity | IDA PMID:12502715 A novel bifunctional wax ester synthase/acyl-CoA:diacylglyce... | ACCEPT | Summary: Diacylglycerol O-acyltransferase activity is the core, well-established molecular function of DGAT1. Note the original_reference (PMID:12502715) is about a bifunctional wax ester synthase/acyl-CoA:DGAT from the bacterium Acinetobacter calcoaceticus, so its basis for annotating Arabidopsis DGAT1 is unclear; the MF is nonetheless overwhelmingly supported by the plant-DGAT references in this review. |
| GO:0009793 embryo development ending in seed dormancy | TAS PMID:12114588 Arabidopsis mutants deficient in diacylglycerol acyltransfer... | KEEP AS NON CORE | Summary: Pleiotropic developmental context of seed oil accumulation rather than a core molecular function. Retained as non-core. [PMID:12114588] |
| GO:0009941 chloroplast envelope | IDA PMID:12177474 A role for diacylglycerol acyltransferase during leaf senesc... | KEEP AS NON CORE | Summary: Experimentally supported senescence-specific localization. In senescing Arabidopsis leaves DGAT1 protein is associated with isolated chloroplasts and purified envelope and thylakoid membranes (but not stroma), where it synthesizes the TAG that accumulates in plastoglobuli from de-esterified galactolipid fatty acids. A genuine secondary localization, retained as non-core relative to the primary ER seed-oil role. [PMID:12177474] Supporting Evidence: PMID:12177474 DGAT1 is present in intact chloroplasts and purified membranes including thylakoid and envelope but not in the stroma |
| GO:0019432 triglyceride biosynthetic process | TAS PMID:12114588 Arabidopsis mutants deficient in diacylglycerol acyltransfer... | ACCEPT | Summary: Core biological process; TAG biosynthesis is DGAT1's primary role. [PMID:12114588] Supporting Evidence: PMID:12114588 In conclusion, we demonstrate that DGAT1 deficiency alters carbohydrate metabolism in the tag1 mutants. |
| GO:0004144 diacylglycerol O-acyltransferase activity | IDA PMID:10386579 Cloning of a cDNA encoding diacylglycerol acyltransferase fr... | ACCEPT | Summary: Core molecular function with direct experimental support from the original characterization of the Arabidopsis DGAT. [PMID:10386579] Supporting Evidence: PMID:10386579 Cloning of a cDNA encoding diacylglycerol acyltransferase from Arabidopsis thaliana and its functional expression. |
| GO:0004144 diacylglycerol O-acyltransferase activity | IMP PMID:10601854 Expression in yeast and tobacco of plant cDNAs encoding acyl... | ACCEPT | Summary: Core molecular function. Plant DGAT cDNAs (including Arabidopsis) expressed in yeast and tobacco confer diacylglycerol acyltransferase activity. [PMID:10601854] Supporting Evidence: PMID:10601854 expression in yeast and tobacco of plant cDNAs encoding acyl CoA:diacylglycerol acyltransferase |
| GO:0016020 membrane | TAS PMID:10601854 Expression in yeast and tobacco of plant cDNAs encoding acyl... | ACCEPT | Summary: Correct but general; DGAT1 is membrane-bound, with the ER membrane being the informative localization. |
| GO:0019432 triglyceride biosynthetic process | TAS PMID:10601854 Expression in yeast and tobacco of plant cDNAs encoding acyl... | ACCEPT | Summary: Core biological process; the tag1 mutant establishes DGAT1's role in seed TAG biosynthesis. [PMID:10601854] |
| GO:0005975 carbohydrate metabolic process | IMP PMID:12114588 Arabidopsis mutants deficient in diacylglycerol acyltransfer... | KEEP AS NON CORE | Summary: Indirect consequence of disrupting seed oil storage (carbon re-partitioning toward carbohydrate), not a direct DGAT1 function. Retained as non-core given the acts_upstream_of_or_within qualifier. [PMID:12114588] |
| GO:0009409 response to cold | IMP PMID:12114588 Arabidopsis mutants deficient in diacylglycerol acyltransfer... | KEEP AS NON CORE | Summary: Pleiotropic stress-response phenotype of the dgat1 mutant rather than a core molecular function. Retained as non-core. [PMID:12114588] |
| GO:0009651 response to salt stress | IMP PMID:12114588 Arabidopsis mutants deficient in diacylglycerol acyltransfer... | KEEP AS NON CORE | Summary: Pleiotropic stress-response phenotype, non-core. [PMID:12114588] |
| GO:0009737 response to abscisic acid | IMP PMID:12114588 Arabidopsis mutants deficient in diacylglycerol acyltransfer... | KEEP AS NON CORE | Summary: Pleiotropic hormone-response phenotype, non-core. [PMID:12114588] |
| GO:0009749 response to glucose | IMP PMID:12114588 Arabidopsis mutants deficient in diacylglycerol acyltransfer... | KEEP AS NON CORE | Summary: Pleiotropic sugar-response phenotype tied to altered carbon partitioning, non-core. [PMID:12114588] |
| GO:0019432 triglyceride biosynthetic process | IMP PMID:11402213 Seed-specific over-expression of an Arabidopsis cDNA encodin... | ACCEPT | Summary: Core biological process supported by mutant phenotype affecting seed TAG. [PMID:11402213] Supporting Evidence: PMID:11402213 Seed-specific over-expression of an Arabidopsis cDNA encoding a diacylglycerol acyltransferase enhances seed oil content and seed weight. |
| GO:0045995 regulation of embryonic development | IMP PMID:11402213 Seed-specific over-expression of an Arabidopsis cDNA encodin... | KEEP AS NON CORE | Summary: Pleiotropic developmental phenotype associated with seed oil reserves, not a core molecular function. Retained as non-core. [PMID:11402213] |
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