SLC1 encodes the major acyl-CoA-dependent 1-acyl-sn-glycerol-3-phosphate acyltransferase (lysophosphatidic acid acyltransferase, LPAAT; EC 2.3.1.51) of Saccharomyces cerevisiae. It acylates the sn-2 position of lysophosphatidic acid to form phosphatidic acid (PA), the branch-point intermediate from which CDP-diacylglycerol-derived glycerophospholipids and, via diacylglycerol, triacylglycerol are made. Slc1 is an integral membrane protein of the AGPAT/PlsC acyltransferase family (HXXXXD motif) that is active in both the endoplasmic reticulum and lipid droplets. In microsomal assays it also accepts other lysophospholipids (lyso-PC, lyso-PE, lyso-PS, lyso-PI) and can operate in reverse on PA, suggesting an additional role in sn-2 acyl remodelling. It is partially redundant with the MBOAT-family acyltransferase Ale1/Slc4; the slc1 ale1 double deletion is lethal. A dominant SLC1 allele was first identified as a suppressor of sphingolipid long-chain base deficiency.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0003841 1-acylglycerol-3-phosphate O-acyltransferase activity | EXP PMID:18154737 A family of eukaryotic lysophospholipid acyltransferases wit... | ACCEPT | Summary: Experimental LPAAT activity for Slc1 attributed by UniProt to the Stahl et al. LPLAT-family paper, which used Slc1 as the reference specific LPA acyltransferase against which the MBOAT Ale1 was contrasted. This is the core catalytic activity of Slc1. Supporting Evidence: PMID:18154737 ScLPLAT differs from the specific lysophosphatidic acid acyltransferase that is encoded by SLC1 file:yeast/SLC1/SLC1-uniprot.txt dependent acylation of lysophosphatidic acid (LPA) to phosphatidic acid |
| GO:0003841 1-acylglycerol-3-phosphate O-acyltransferase activity | EXP PMID:26643989 Possible Role of Different Yeast and Plant Lysophospholipid:... | ACCEPT | Summary: Microsomes from yeast overexpressing Slc1 were assayed with oleoyl-lysophospholipids; Slc1 efficiently acylated lyso-PA (and was also reversible on PA). Supports LPAAT activity directly. Supporting Evidence: PMID:26643989 The lysophospholipid specificity of Slc1 was close to what was reported earlier [3], showing a broad acyl specificity by accepting well all lysophospholipids offered PMID:26643989 Slc1 has no detectable reverse reaction towards PtdCho substrate, but has the highest capacity of reversibility towards the PtdOH substrate of all tested enzymes. |
| GO:0003841 1-acylglycerol-3-phosphate O-acyltransferase activity | EXP PMID:9401016 Biosynthesis of phosphatidic acid in lipid particles and end... | ACCEPT | Summary: In lipid particles from the slc1 disruptant acylation of glycerol-3-phosphate stopped at lysophosphatidic acid, showing that the LPA-to-PA step depends on Slc1. Classical evidence for Slc1 LPAAT activity. Supporting Evidence: PMID:9401016 the second step, acylation of lysophosphatidic acid, requires S1c1p |
| GO:0003841 1-acylglycerol-3-phosphate O-acyltransferase activity | IBA GO_REF:0000033 | ACCEPT | Summary: PANTHER IBA for LPAAT activity in the AGPAT family (PTHR10434), seeded by human AGPAT1/2, mouse, Arabidopsis and Slc1 itself (SGD:S000002210). Slc1 sits squarely in the experimentally characterised clade; the IBA is consistent with direct evidence. Supporting Evidence: PMID:17675291 In yeast, it is generated from lysophosphatidic acid, which is acylated by Slc1p, an sn-2-specific, acyl-coenzyme A-dependent 1-acylglycerol-3-phosphate O-acyltransferase. |
| GO:0003841 1-acylglycerol-3-phosphate O-acyltransferase activity | IDA PMID:9212466 Modification of seed oil content and acyl composition in the... | ACCEPT | Summary: The SLC1-1 allele product, expressed in a yeast slc deletion strain and in plants, acylated sn-1 oleoyl-LPA with a range of acyl-CoAs in vitro, directly demonstrating sn-2 LPAAT activity. Supporting Evidence: PMID:9212466 The SLC1-1 gene product was shown in vitro to encode an sn-2 acyltransferase capable of acylating sn-1 oleoyl-lysophosphatidic acid |
| GO:0003841 1-acylglycerol-3-phosphate O-acyltransferase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Automated annotation from InterPro IPR004552 (AGP acyltransferase), RHEA:19709 and EC 2.3.1.51. Correct for Slc1; redundant with experimental evidence. Supporting Evidence: file:yeast/SLC1/SLC1-uniprot.txt dependent acylation of lysophosphatidic acid (LPA) to phosphatidic acid |
| GO:0003841 1-acylglycerol-3-phosphate O-acyltransferase activity | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways RCA (PWY3O-6407, diacylglycerol and triacylglycerol biosynthesis) assigning the LPAAT step (EC 2.3.1.51) to Slc1. The reaction assignment is correct and matches experimental data. Supporting Evidence: PMID:17675291 In yeast, it is generated from lysophosphatidic acid, which is acylated by Slc1p, an sn-2-specific, acyl-coenzyme A-dependent 1-acylglycerol-3-phosphate O-acyltransferase. |
| GO:0003841 1-acylglycerol-3-phosphate O-acyltransferase activity | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways RCA (PWY3O-6499, phosphatidate biosynthesis I, dihydroxyacetone-phosphate route). The LPA produced by Gpt2/Sct1 + Ayr1 from DHAP is acylated by Slc1; the LPAAT assignment is correct. Supporting Evidence: PMID:17675291 In yeast, it is generated from lysophosphatidic acid, which is acylated by Slc1p, an sn-2-specific, acyl-coenzyme A-dependent 1-acylglycerol-3-phosphate O-acyltransferase. |
| GO:0003841 1-acylglycerol-3-phosphate O-acyltransferase activity | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways RCA (PWY3O-6635, phosphatidate biosynthesis II, glycerol-3-phosphate route). Slc1 catalyses the second acylation (LPA to PA); assignment correct. Supporting Evidence: PMID:9401016 the second step, acylation of lysophosphatidic acid, requires S1c1p |
| GO:0003841 1-acylglycerol-3-phosphate O-acyltransferase activity | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways RCA (TRIGLSYN-PWY, triacylglycerol biosynthesis). The LPAAT step in this pathway is correctly attributed to Slc1. Supporting Evidence: PMID:17675291 In yeast, it is generated from lysophosphatidic acid, which is acylated by Slc1p, an sn-2-specific, acyl-coenzyme A-dependent 1-acylglycerol-3-phosphate O-acyltransferase. |
| GO:0005783 endoplasmic reticulum | HDA PMID:26928762 One library to make them all: streamlining the creation of y... | ACCEPT | Summary: High-throughput SWAp-Tag GFP localisation placed Slc1 in the ER. Consistent with microsomal LPAAT activity and the ER being one of the two sites of PA synthesis. Supporting Evidence: PMID:24868093 While both Say1 and Rer2 are present and active at the LD and ER, similar to Ayr1 (60), Gpt2 (61), and Slc1 (62), not all proteins are active in all subcellular populations. |
| GO:0005783 endoplasmic reticulum | IBA GO_REF:0000033 | ACCEPT | Summary: IBA is_active_in ER from AGPAT orthologues (human AGPAT1/2, mouse). Slc1 is active in the ER as well as in lipid droplets. Supporting Evidence: PMID:24868093 While both Say1 and Rer2 are present and active at the LD and ER, similar to Ayr1 (60), Gpt2 (61), and Slc1 (62), not all proteins are active in all subcellular populations. |
| GO:0005811 lipid droplet | EXP PMID:18154737 A family of eukaryotic lysophospholipid acyltransferases wit... | ACCEPT | Summary: UniProt-curated lipid droplet localisation (Stahl et al.). Slc1 is a constitutive lipid droplet protein with LPAAT activity there. Supporting Evidence: file:yeast/SLC1/SLC1-uniprot.txt SUBCELLULAR LOCATION: Lipid droplet {ECO:0000269|PubMed:18154737, PMID:24868093 Twelve proteins (Ayr1, Eht1, Erg1, Erg6, Erg7, Faa1, Faa4, Fat1, Pet10, Slc1, Tgl1, and Tgl3) were detected in the current work and all reported proteomes. |
| GO:0005811 lipid droplet | EXP PMID:21820081 Lipid particles/droplets of the yeast Saccharomyces cerevisi... | ACCEPT | Summary: Lipid droplet localisation from the Grillitsch et al. LD proteome revisited study; Slc1 is a recurrent component of yeast LD proteomes. Supporting Evidence: PMID:24868093 Twelve proteins (Ayr1, Eht1, Erg1, Erg6, Erg7, Faa1, Faa4, Fat1, Pet10, Slc1, Tgl1, and Tgl3) were detected in the current work and all reported proteomes. |
| GO:0005811 lipid droplet | IDA PMID:10515935 Identification and characterization of major lipid particle ... | ACCEPT | Summary: Athenstaedt et al. 1999 lipid particle proteomics; the paper explicitly lists Slc1 as a lipid particle component contributing to PA biosynthesis (though not itself detected by MS in that study, the curator's IDA follows earlier biochemical localisation). Supporting Evidence: PMID:10515935 the 1-acylglycerol-3-phosphate acyltransferase Slc1p, which contribute to phosphatidic acid biosynthesis, were previously identified as lipid particle components |
| GO:0005811 lipid droplet | IDA PMID:24868093 High confidence proteomic analysis of yeast LDs identifies a... | ACCEPT | Summary: High-confidence LD proteome (Currie et al. 2014) found Slc1 among the twelve constitutive LD proteins and active at both LD and ER. Supporting Evidence: PMID:24868093 Twelve proteins (Ayr1, Eht1, Erg1, Erg6, Erg7, Faa1, Faa4, Fat1, Pet10, Slc1, Tgl1, and Tgl3) were detected in the current work and all reported proteomes. PMID:24868093 While both Say1 and Rer2 are present and active at the LD and ER, similar to Ayr1 (60), Gpt2 (61), and Slc1 (62), not all proteins are active in all subcellular populations. |
| GO:0005811 lipid droplet | IEA GO_REF:0000044 | ACCEPT | Summary: UniProt subcellular-location mapping (SL-0154) to lipid droplet; correct and supported by multiple direct studies. Supporting Evidence: PMID:9401016 Two-dimensional gel electrophoresis confirmed that S1c1p is a component of lipid particles. |
| GO:0005829 cytosol | RCA GO_REF:0000123 | MODIFY | Summary: YeastPathways RCA places the LPAAT reaction (PWY3O-6407) in the cytosol by default. Slc1 is an integral membrane enzyme acting on membrane-embedded LPA in the ER and lipid droplet; its activity is not in the cytosol. Reason: Wrong compartment from pathway default; replace with the membrane compartment where Slc1 acts. Proposed replacements: endoplasmic reticulum membrane Supporting Evidence: PMID:24868093 While both Say1 and Rer2 are present and active at the LD and ER, similar to Ayr1 (60), Gpt2 (61), and Slc1 (62), not all proteins are active in all subcellular populations. |
| GO:0005829 cytosol | RCA GO_REF:0000123 | MODIFY | Summary: Cytosol RCA from PWY3O-6499 (DHAP route). Same default-compartment artefact: Slc1 is an ER/lipid-droplet membrane enzyme. Reason: Replace cytosol with ER membrane. Proposed replacements: endoplasmic reticulum membrane Supporting Evidence: PMID:24868093 While both Say1 and Rer2 are present and active at the LD and ER, similar to Ayr1 (60), Gpt2 (61), and Slc1 (62), not all proteins are active in all subcellular populations. |
| GO:0005829 cytosol | RCA GO_REF:0000123 | MODIFY | Summary: Cytosol RCA from PWY3O-6635 (glycerol-3-phosphate route). Slc1 acylates LPA in ER and lipid particle membranes, not in the cytosol. Reason: Replace cytosol with ER membrane. Proposed replacements: endoplasmic reticulum membrane Supporting Evidence: PMID:9401016 the second step, acylation of lysophosphatidic acid, requires S1c1p |
| GO:0005829 cytosol | RCA GO_REF:0000123 | MODIFY | Summary: Cytosol RCA from TRIGLSYN-PWY. Default pathway compartment; Slc1 is membrane-embedded in ER and LDs. Reason: Replace cytosol with ER membrane. Proposed replacements: endoplasmic reticulum membrane Supporting Evidence: PMID:24868093 While both Say1 and Rer2 are present and active at the LD and ER, similar to Ayr1 (60), Gpt2 (61), and Slc1 (62), not all proteins are active in all subcellular populations. |
| GO:0006644 phospholipid metabolic process | IEA GO_REF:0000117 | TOO GENERAL | Summary: ARBA machine-learning annotation to phospholipid metabolic process. Broad but correct: Slc1 makes PA and also acylates other lysophospholipids. Supporting Evidence: PMID:17675291 affinity-purified Slc1p displays Mg2+-dependent acyltransferase activity not only toward lysophosphatidic acid but also lyso forms of phosphatidylserine and phosphatidylinositol |
| GO:0006654 phosphatidic acid biosynthetic process | IBA GO_REF:0000033 | ACCEPT | Summary: IBA for phosphatidic acid biosynthetic process in the AGPAT clade. Slc1 directly catalyses PA formation; this is its core process. Supporting Evidence: PMID:17675291 In yeast, it is generated from lysophosphatidic acid, which is acylated by Slc1p, an sn-2-specific, acyl-coenzyme A-dependent 1-acylglycerol-3-phosphate O-acyltransferase. PMID:9401016 the second step, acylation of lysophosphatidic acid, requires S1c1p |
| GO:0006654 phosphatidic acid biosynthetic process | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways RCA (PWY3O-6635 phosphatidate biosynthesis II). Correct core process for Slc1. Supporting Evidence: PMID:9401016 the second step, acylation of lysophosphatidic acid, requires S1c1p |
| GO:0008654 phospholipid biosynthetic process | IEA GO_REF:0000002 | ACCEPT | Summary: InterPro IPR004552 mapping to phospholipid biosynthetic process. Correct parent of PA biosynthesis; PA is the precursor of all glycerophospholipids. Supporting Evidence: PMID:17675291 In yeast, it is generated from lysophosphatidic acid, which is acylated by Slc1p, an sn-2-specific, acyl-coenzyme A-dependent 1-acylglycerol-3-phosphate O-acyltransferase. |
| GO:0008654 phospholipid biosynthetic process | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways RCA (PWY3O-6407) to phospholipid biosynthetic process. Correct general process for the LPAAT step. Supporting Evidence: PMID:17675291 In yeast, it is generated from lysophosphatidic acid, which is acylated by Slc1p, an sn-2-specific, acyl-coenzyme A-dependent 1-acylglycerol-3-phosphate O-acyltransferase. |
| GO:0008654 phospholipid biosynthetic process | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways RCA (PWY3O-6499) to phospholipid biosynthetic process. Correct general process for the LPAAT step. Supporting Evidence: PMID:17675291 In yeast, it is generated from lysophosphatidic acid, which is acylated by Slc1p, an sn-2-specific, acyl-coenzyme A-dependent 1-acylglycerol-3-phosphate O-acyltransferase. |
| GO:0016020 membrane | IEA GO_REF:0000002 | TOO GENERAL | Summary: InterPro-based membrane annotation. True (Slc1 is an integral membrane protein) but uninformative relative to ER membrane and lipid droplet. Supporting Evidence: PMID:24868093 While both Say1 and Rer2 are present and active at the LD and ER, similar to Ayr1 (60), Gpt2 (61), and Slc1 (62), not all proteins are active in all subcellular populations. |
| GO:0016024 CDP-diacylglycerol biosynthetic process | IEA GO_REF:0000041 | KEEP AS NON CORE | Summary: UniPathway mapping (UPA00557, CDP-diacylglycerol from glycerol-3-phosphate, step 2/3). Slc1 makes PA, which Cds1 converts to CDP-DAG; PA is also channelled to DAG/TAG, so CDP-DAG biosynthesis is one downstream use of the Slc1 product rather than its defining process. Reason: Pathway-level annotation; the specific step Slc1 performs is PA biosynthesis. Supporting Evidence: file:yeast/SLC1/SLC1-uniprot.txt dependent acylation of lysophosphatidic acid (LPA) to phosphatidic acid |
| GO:0016746 acyltransferase activity | IEA GO_REF:0000002 | TOO GENERAL | Summary: InterPro IPR002123 (phospholipid/glycerol acyltransferase) mapping to acyltransferase activity. Correct but general parent of LPAAT activity. Supporting Evidence: file:yeast/SLC1/SLC1-uniprot.txt dependent acylation of lysophosphatidic acid (LPA) to phosphatidic acid |
| GO:0019432 triglyceride biosynthetic process | RCA GO_REF:0000123 | KEEP AS NON CORE | Summary: YeastPathways RCA (TRIGLSYN-PWY). Slc1 generates PA that Pah1 dephosphorylates to DAG for TAG synthesis by Dga1/Lro1, so it performs an upstream step of de novo TAG synthesis; the PA pool is shared with phospholipid synthesis. Reason: Valid pathway participation but secondary to phospholipid/PA synthesis. Supporting Evidence: PMID:17675291 In yeast, it is generated from lysophosphatidic acid, which is acylated by Slc1p, an sn-2-specific, acyl-coenzyme A-dependent 1-acylglycerol-3-phosphate O-acyltransferase. |
| GO:0046474 glycerophospholipid biosynthetic process | IGI PMID:17675291 SLC1 and SLC4 encode partially redundant acyl-coenzyme A 1-a... | ACCEPT | Summary: Genetic interaction with ALE1/SLC4 (SGD:S000005701): slc1 ale1 double deletion is lethal and the two produce nearly the same glycerophospholipid profile, showing Slc1 is required for glycerophospholipid synthesis. Supporting Evidence: PMID:17675291 The simultaneous deletion of SLC1 and SLC4 is lethal. PMID:17675291 Phosphatidic acid is the intermediate, from which all glycerophospholipids are synthesized. |
| GO:0047184 1-acylglycerophosphocholine O-acyltransferase activity | EXP PMID:26643989 Possible Role of Different Yeast and Plant Lysophospholipid:... | KEEP AS NON CORE | Summary: Microsomal assays showed Slc1 acylates lyso-PC in the forward direction. In vivo, PC remodelling is mainly attributed to Ale1, so for Slc1 this is a real but secondary activity. Reason: Demonstrated in vitro; not the physiological core activity. Supporting Evidence: PMID:26643989 The lysophospholipid specificity of Slc1 was close to what was reported earlier [3], showing a broad acyl specificity by accepting well all lysophospholipids offered PMID:26643989 lysoPtdCho was also a good substrate in the forward reaction |
| GO:0047184 1-acylglycerophosphocholine O-acyltransferase activity | IEA GO_REF:0000120 | KEEP AS NON CORE | Summary: RHEA:12937/EC 2.3.1.23 mapping, derived from the UniProt catalytic-activity annotation based on Jasieniecka-Gazarkiewicz et al. Correct but a secondary activity for Slc1. Supporting Evidence: PMID:26643989 The lysophospholipid specificity of Slc1 was close to what was reported earlier [3], showing a broad acyl specificity by accepting well all lysophospholipids offered |
| GO:0106262 1-acylglycerophosphoethanolamine O-acyltransferase activity | EXP PMID:26643989 Possible Role of Different Yeast and Plant Lysophospholipid:... | KEEP AS NON CORE | Summary: Microsomal assays showed Slc1 acylates lyso-PE and catalyses a measurable reverse reaction with PE. Secondary activity relative to LPA acylation. Supporting Evidence: PMID:26643989 The lysophospholipid specificity of Slc1 was close to what was reported earlier [3], showing a broad acyl specificity by accepting well all lysophospholipids offered PMID:26643989 The only substrate used to any significant extent in the reverse reaction by Slc1 was PtdOH and, to a lower extent, PtdEtn |
| GO:0106262 1-acylglycerophosphoethanolamine O-acyltransferase activity | IEA GO_REF:0000116 | KEEP AS NON CORE | Summary: RHEA:32995 mapping from UniProt catalytic activity; correct for Slc1 but secondary. Supporting Evidence: PMID:26643989 The lysophospholipid specificity of Slc1 was close to what was reported earlier [3], showing a broad acyl specificity by accepting well all lysophospholipids offered |
| GO:0106263 1-acylglycerophosphoserine O-acyltransferase activity | IEA GO_REF:0000116 | KEEP AS NON CORE | Summary: RHEA:37407 mapping; UniProt cites affinity-purified Slc1 acylating 1-oleoyl-lyso-PS (Benghezal et al. 2007). Real but secondary activity. Supporting Evidence: PMID:17675291 affinity-purified Slc1p displays Mg2+-dependent acyltransferase activity not only toward lysophosphatidic acid but also lyso forms of phosphatidylserine and phosphatidylinositol |
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Download this section (compressed HTML)Q: What fraction of cellular PA synthesis is carried out by lipid-droplet-resident versus ER-resident Slc1, and is the LD pool physiologically significant for TAG synthesis?
Q: Does Slc1 contribute to sn-2 acyl remodelling of PI and PS in vivo, as suggested by its in vitro lysophospholipid acyltransferase activities?
Experiment: Lipidomic flux analysis (13C-oleate pulse-chase) in slc1 and ale1 single mutants and an Slc1 variant restricted to ER or LD, to separate de novo PA synthesis from remodelling activity.
1-acyl-sn-glycerol-3-phosphate acyltransferase; catalyzes the acylation of lysophosphatidic acid to form phosphatidic acid, a key intermediate in lipid metabolism; enzymatic activity detected in lipid particles and microsomes
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