Pis1 (YPR113W) is the CDP-diacylglycerol--inositol 3-phosphatidyltransferase (phosphatidylinositol synthase, EC 2.7.8.11) of Saccharomyces cerevisiae, an essential polytopic membrane enzyme of the CDP-alcohol phosphatidyltransferase family. It transfers the phosphatidyl group of CDP-diacylglycerol to myo-inositol, releasing CMP, and is the sole route to phosphatidylinositol, the precursor of phosphoinositides, inositol sphingolipids and GPI anchors. Activity requires Mn2+ or Mg2+, is constitutively expressed, and in vivo is limited mainly by myo-inositol availability. Pis1 activity is found in the ER (microsomes), the Golgi and the cytosolic face of the mitochondrial outer membrane.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000139 Golgi membrane | EXP PMID:8543066 Phospholipid-synthesizing enzymes in Golgi membranes of the ... | ACCEPT | Summary: Leber et al. 1995 detected PI synthase activity in purified Golgi membranes at higher specific activity than ER. Supporting Evidence: PMID:8543066 Two phospholipid-synthesizing enzymes, namely phosphatidylinositol synthase and sn-1,2-diacylglycerol cholinephosphotransferase, are detected in the Golgi at a specific activity which exceeds that of the endoplasmic reticulum. |
| GO:0000139 Golgi membrane | IEA GO_REF:0000044 | ACCEPT | Summary: UniProt subcellular location (Golgi apparatus membrane) mapping. Supported by Golgi activity data. Supporting Evidence: PMID:8543066 Two phospholipid-synthesizing enzymes, namely phosphatidylinositol synthase and sn-1,2-diacylglycerol cholinephosphotransferase, are detected in the Golgi at a specific activity which exceeds that of the endoplasmic reticulum. |
| GO:0003881 CDP-diacylglycerol-inositol 3-phosphatidyltransferase activity | EXP PMID:6274497 Solubilization of microsomal-associated phosphatidylserine s... | ACCEPT | Summary: Carman & Matas 1981 solubilized and kinetically characterized microsomal PI synthase (Km CDP-DAG 70 uM, inositol 0.1 mM). Core activity. Supporting Evidence: PMID:6274497 The apparent Km values for CDP-diacylglycerol and inositol for the phosphatidylinositol synthase reaction were 70 microM and 0.1 mM, respectively. |
| GO:0003881 CDP-diacylglycerol-inositol 3-phosphatidyltransferase activity | IBA GO_REF:0000033 | ACCEPT | Summary: IBA from PTN000394714 (eukaryotic PIS incl. S. pombe, Candida, fly, plant members and Pis1). Core activity. Supporting Evidence: PMID:6088233 Introduction of the cloned plasmid into the mutant restored both growth of cells and CDPdiacylglycerol-inositol 3-phosphatidyltransferase activity. PMID:3005284 Purified membrane-associated phosphatidylinositol synthase (CDP diacylglycerol:myo-inositol 3-phosphatidyltransferase, EC 2.7.8.11) from Saccharomyces cerevisiae was reconstituted into unilamellar phospholipid vesicles. |
| GO:0003881 CDP-diacylglycerol-inositol 3-phosphatidyltransferase activity | IDA PMID:3005284 Phosphatidylinositol synthase from Saccharomyces cerevisiae.... | ACCEPT | Summary: Purified PI synthase reconstituted into vesicles and characterized. Core activity. Supporting Evidence: PMID:3005284 Purified membrane-associated phosphatidylinositol synthase (CDP diacylglycerol:myo-inositol 3-phosphatidyltransferase, EC 2.7.8.11) from Saccharomyces cerevisiae was reconstituted into unilamellar phospholipid vesicles. |
| GO:0003881 CDP-diacylglycerol-inositol 3-phosphatidyltransferase activity | IEA GO_REF:0000120 | ACCEPT | Summary: ARBA/RHEA:11580/EC 2.7.8.11 mapping. Correct. Supporting Evidence: file:yeast/PIS1/PIS1-uniprot.txt FUNCTION: Catalyzes the synthesis of phosphatidylinositol (PtdIns). |
| GO:0003881 CDP-diacylglycerol-inositol 3-phosphatidyltransferase activity | IMP PMID:6088233 Molecular cloning of the gene encoding CDPdiacylglycerol-ino... | ACCEPT | Summary: Nikawa & Yamashita 1984: cloned PIS1 restores growth and activity of a pis mutant with high-Km enzyme; multicopy gives 8-fold activity. Supporting Evidence: PMID:6088233 Introduction of the cloned plasmid into the mutant restored both growth of cells and CDPdiacylglycerol-inositol 3-phosphatidyltransferase activity. PMID:6088233 CDPdiacylglycerol-inositol 3-phosphatidyltransferase activity in the transformant was eight fold higher than that in the wild-type strain. |
| GO:0003881 CDP-diacylglycerol-inositol 3-phosphatidyltransferase activity | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways (PHOS-PWY, PWY3O-2, PWY3O-3 PI biosynthesis) assigns Pis1 to CDP-DAG + myo-inositol -> PI + CMP (EC 2.7.8.11). Correct. Supporting Evidence: file:yeast/PIS1/PIS1-uniprot.txt FUNCTION: Catalyzes the synthesis of phosphatidylinositol (PtdIns). |
| GO:0003881 CDP-diacylglycerol-inositol 3-phosphatidyltransferase activity | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways (PHOS-PWY, PWY3O-2, PWY3O-3 PI biosynthesis) assigns Pis1 to CDP-DAG + myo-inositol -> PI + CMP (EC 2.7.8.11). Correct. Supporting Evidence: file:yeast/PIS1/PIS1-uniprot.txt FUNCTION: Catalyzes the synthesis of phosphatidylinositol (PtdIns). |
| GO:0003881 CDP-diacylglycerol-inositol 3-phosphatidyltransferase activity | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways (PHOS-PWY, PWY3O-2, PWY3O-3 PI biosynthesis) assigns Pis1 to CDP-DAG + myo-inositol -> PI + CMP (EC 2.7.8.11). Correct. Supporting Evidence: file:yeast/PIS1/PIS1-uniprot.txt FUNCTION: Catalyzes the synthesis of phosphatidylinositol (PtdIns). |
| GO:0005737 cytoplasm | IEA GO_REF:0000117 | KEEP AS NON CORE | Summary: ARBA rule maps to cytoplasm. True only in the broad sense (endomembranes are within the cytoplasm); uninformative for a multi-pass membrane protein. Reason: Overly general location; ER/Golgi/MOM membranes are the informative terms. |
| GO:0005739 mitochondrion | HDA PMID:16823961 Toward the complete yeast mitochondrial proteome: multidimen... | ACCEPT | Summary: Detected in the mitochondrial proteome (Reinders et al. 2006); consistent with PI synthase activity on the mitochondrial outer membrane. Supporting Evidence: PMID:3005242 Glycerolphosphate acyltransferase, phosphatidylinositol synthase, and phosphatidylserine synthase were exposed at the cytosolic surface of the outer mitochondrial membrane. |
| GO:0005741 mitochondrial outer membrane | EXP PMID:16823961 Toward the complete yeast mitochondrial proteome: multidimen... | ACCEPT | Summary: Mitochondrial proteomics (Reinders et al. 2006) used for outer membrane assignment; consistent with activity data showing PI synthase on the cytosolic face of the MOM. Supporting Evidence: PMID:3005242 Glycerolphosphate acyltransferase, phosphatidylinositol synthase, and phosphatidylserine synthase were exposed at the cytosolic surface of the outer mitochondrial membrane. |
| GO:0005741 mitochondrial outer membrane | EXP PMID:6274497 Solubilization of microsomal-associated phosphatidylserine s... | ACCEPT | Summary: Carman & Matas 1981 (abstract describes microsomal enzyme); curator assignment to MOM from full text deferred to, and independently supported by Kuchler et al. 1986. Supporting Evidence: PMID:3005242 Glycerolphosphate acyltransferase, phosphatidylinositol synthase, and phosphatidylserine synthase were exposed at the cytosolic surface of the outer mitochondrial membrane. |
| GO:0005741 mitochondrial outer membrane | IDA PMID:3005242 Subcellular and submitochondrial localization of phospholipi... | ACCEPT | Summary: Kuchler et al. 1986 found PI synthase exposed at the cytosolic surface of the outer mitochondrial membrane. Supporting Evidence: PMID:3005242 Glycerolphosphate acyltransferase, phosphatidylinositol synthase, and phosphatidylserine synthase were exposed at the cytosolic surface of the outer mitochondrial membrane. |
| GO:0005741 mitochondrial outer membrane | IEA GO_REF:0000044 | ACCEPT | Summary: UniProt subcellular location mapping (Mitochondrion outer membrane). Correct. Supporting Evidence: PMID:3005242 Glycerolphosphate acyltransferase, phosphatidylinositol synthase, and phosphatidylserine synthase were exposed at the cytosolic surface of the outer mitochondrial membrane. |
| GO:0005783 endoplasmic reticulum | HDA PMID:26928762 One library to make them all: streamlining the creation of y... | ACCEPT | Summary: High-throughput GFP library localizes Pis1 to the ER; consistent with microsomal PI synthase. Supporting Evidence: PMID:26928762 we found that most new localization assignments were to the ER, punctate structures and vacuole PMID:6274497 were solubilized from the microsomal fraction of Saccharomyces cerevisiae |
| GO:0005789 endoplasmic reticulum membrane | IEA GO_REF:0000044 | ACCEPT | Summary: UniProt subcellular location (ER membrane, multi-pass) mapping. Correct; principal site with microsomal activity. Supporting Evidence: file:yeast/PIS1/PIS1-uniprot.txt reticulum membrane {ECO:0000305|PubMed:25687304}; Multi-pass membrane PMID:6274497 were solubilized from the microsomal fraction of Saccharomyces cerevisiae |
| GO:0005794 Golgi apparatus | IBA GO_REF:0000033 | ACCEPT | Summary: IBA is_active_in Golgi from PTN000394714 (incl. Arabidopsis PIS and Pis1 itself). Consistent with Golgi activity data. Supporting Evidence: PMID:8543066 Two phospholipid-synthesizing enzymes, namely phosphatidylinositol synthase and sn-1,2-diacylglycerol cholinephosphotransferase, are detected in the Golgi at a specific activity which exceeds that of the endoplasmic reticulum. |
| GO:0005794 Golgi apparatus | IDA PMID:8543066 Phospholipid-synthesizing enzymes in Golgi membranes of the ... | ACCEPT | Summary: PI synthase activity enriched in isolated Golgi membranes. Supporting Evidence: PMID:8543066 Two phospholipid-synthesizing enzymes, namely phosphatidylinositol synthase and sn-1,2-diacylglycerol cholinephosphotransferase, are detected in the Golgi at a specific activity which exceeds that of the endoplasmic reticulum. |
| GO:0005829 cytosol | RCA GO_REF:0000123 | REMOVE | Summary: YeastPathways RCA places the PI synthase step in the cytosol. Pis1 is a six-pass integral membrane protein acting on membrane CDP-DAG; cytosol is wrong. Reason: Localization default of the pathway conversion; contradicted by membrane localization data. Supporting Evidence: PMID:6274497 were solubilized from the microsomal fraction of Saccharomyces cerevisiae PMID:8543066 Two phospholipid-synthesizing enzymes, namely phosphatidylinositol synthase and sn-1,2-diacylglycerol cholinephosphotransferase, are detected in the Golgi at a specific activity which exceeds that of the endoplasmic reticulum. |
| GO:0005829 cytosol | RCA GO_REF:0000123 | REMOVE | Summary: YeastPathways RCA places the PI synthase step in the cytosol. Pis1 is a six-pass integral membrane protein acting on membrane CDP-DAG; cytosol is wrong. Reason: Localization default of the pathway conversion; contradicted by membrane localization data. Supporting Evidence: PMID:6274497 were solubilized from the microsomal fraction of Saccharomyces cerevisiae PMID:8543066 Two phospholipid-synthesizing enzymes, namely phosphatidylinositol synthase and sn-1,2-diacylglycerol cholinephosphotransferase, are detected in the Golgi at a specific activity which exceeds that of the endoplasmic reticulum. |
| GO:0005829 cytosol | RCA GO_REF:0000123 | REMOVE | Summary: YeastPathways RCA places the PI synthase step in the cytosol. Pis1 is a six-pass integral membrane protein acting on membrane CDP-DAG; cytosol is wrong. Reason: Localization default of the pathway conversion; contradicted by membrane localization data. Supporting Evidence: PMID:6274497 were solubilized from the microsomal fraction of Saccharomyces cerevisiae PMID:8543066 Two phospholipid-synthesizing enzymes, namely phosphatidylinositol synthase and sn-1,2-diacylglycerol cholinephosphotransferase, are detected in the Golgi at a specific activity which exceeds that of the endoplasmic reticulum. |
| GO:0006661 phosphatidylinositol biosynthetic process | IBA GO_REF:0000033 | ACCEPT | Summary: IBA from PTN000394714. Core process. Supporting Evidence: file:yeast/PIS1/PIS1-uniprot.txt FUNCTION: Catalyzes the synthesis of phosphatidylinositol (PtdIns). |
| GO:0006661 phosphatidylinositol biosynthetic process | IDA PMID:3005284 Phosphatidylinositol synthase from Saccharomyces cerevisiae.... | ACCEPT | Summary: Purified, reconstituted PI synthase makes PI. Core process. Supporting Evidence: PMID:3005284 Purified membrane-associated phosphatidylinositol synthase (CDP diacylglycerol:myo-inositol 3-phosphatidyltransferase, EC 2.7.8.11) from Saccharomyces cerevisiae was reconstituted into unilamellar phospholipid vesicles. |
| GO:0006661 phosphatidylinositol biosynthetic process | IEA GO_REF:0000117 | ACCEPT | Summary: ARBA mapping to PI biosynthetic process. Correct. Supporting Evidence: file:yeast/PIS1/PIS1-uniprot.txt FUNCTION: Catalyzes the synthesis of phosphatidylinositol (PtdIns). |
| GO:0006661 phosphatidylinositol biosynthetic process | IMP PMID:6088233 Molecular cloning of the gene encoding CDPdiacylglycerol-ino... | ACCEPT | Summary: pis mutant with defective enzyme; complementation by PIS1. PI content responds to inositol supply. Supporting Evidence: PMID:6088233 Introduction of the cloned plasmid into the mutant restored both growth of cells and CDPdiacylglycerol-inositol 3-phosphatidyltransferase activity. |
| GO:0006661 phosphatidylinositol biosynthetic process | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways PWY3O-3 (PI biosynthesis) RCA. Correct. Supporting Evidence: file:yeast/PIS1/PIS1-uniprot.txt FUNCTION: Catalyzes the synthesis of phosphatidylinositol (PtdIns). |
| GO:0008654 phospholipid biosynthetic process | IEA GO_REF:0000002 | ACCEPT | Summary: InterPro IPR000462 (CDP-alcohol phosphatidyltransferase) to phospholipid biosynthetic process. Correct general term. Supporting Evidence: file:yeast/PIS1/PIS1-uniprot.txt FUNCTION: Catalyzes the synthesis of phosphatidylinositol (PtdIns). |
| GO:0008654 phospholipid biosynthetic process | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways superpathway RCA. Correct general term. Supporting Evidence: file:yeast/PIS1/PIS1-uniprot.txt FUNCTION: Catalyzes the synthesis of phosphatidylinositol (PtdIns). |
| GO:0008654 phospholipid biosynthetic process | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways superpathway RCA. Correct general term. Supporting Evidence: file:yeast/PIS1/PIS1-uniprot.txt FUNCTION: Catalyzes the synthesis of phosphatidylinositol (PtdIns). |
| GO:0012505 endomembrane system | IEA GO_REF:0000117 | ACCEPT | Summary: ARBA mapping to endomembrane system. Correct summary of ER/Golgi/MOM distribution. Supporting Evidence: PMID:8543066 Two phospholipid-synthesizing enzymes, namely phosphatidylinositol synthase and sn-1,2-diacylglycerol cholinephosphotransferase, are detected in the Golgi at a specific activity which exceeds that of the endoplasmic reticulum. |
| GO:0016020 membrane | IDA PMID:6274497 Solubilization of microsomal-associated phosphatidylserine s... | ACCEPT | Summary: Activity is membrane (microsome) associated and must be solubilized with detergent. Supporting Evidence: PMID:6274497 were solubilized from the microsomal fraction of Saccharomyces cerevisiae |
| GO:0016020 membrane | IEA GO_REF:0000002 | ACCEPT | Summary: InterPro IPR000462 to membrane. Correct, general. Supporting Evidence: PMID:6274497 were solubilized from the microsomal fraction of Saccharomyces cerevisiae |
| GO:0016780 phosphotransferase activity, for other substituted phosphate groups | IEA GO_REF:0000002 | MODIFY | Summary: InterPro IPR000462 to generic 'phosphotransferase activity, for other substituted phosphate groups'. Correct parent; specific activity known. Reason: Replace with the specific activity. Proposed replacements: CDP-diacylglycerol-inositol 3-phosphatidyltransferase activity Supporting Evidence: PMID:3005284 Purified membrane-associated phosphatidylinositol synthase (CDP diacylglycerol:myo-inositol 3-phosphatidyltransferase, EC 2.7.8.11) from Saccharomyces cerevisiae was reconstituted into unilamellar phospholipid vesicles. |
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Download this section (compressed HTML)Phosphatidylinositol synthase; required for biosynthesis of phosphatidylinositol, which is a precursor for polyphosphoinositides, sphingolipids, and glycolipid anchors for some of the plasma membrane proteins
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