Enzymes
| UniProtKB help_outline | 3 proteins |
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- Name help_outline a CDP-1,2-diacyl-sn-glycerol Identifier CHEBI:58332 Charge -2 Formula C14H17N3O15P2R2 SMILEShelp_outline Nc1ccn([C@@H]2O[C@H](COP([O-])(=O)OP([O-])(=O)OC[C@@H](COC([*])=O)OC([*])=O)[C@@H](O)[C@H]2O)c(=O)n1 2D coordinates Mol file for the small molecule Search links Involved in 19 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline myo-inositol Identifier CHEBI:17268 (CAS: 87-89-8) help_outline Charge 0 Formula C6H12O6 InChIKeyhelp_outline CDAISMWEOUEBRE-GPIVLXJGSA-N SMILEShelp_outline O[C@H]1[C@H](O)[C@@H](O)[C@H](O)[C@H](O)[C@@H]1O 2D coordinates Mol file for the small molecule Search links Involved in 25 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline a 1,2-diacyl-sn-glycero-3-phospho-(1D-myo-inositol) Identifier CHEBI:57880 Charge -1 Formula C11H16O13PR2 SMILEShelp_outline [C@@H]1([C@@H]([C@@H]([C@@H]([C@H]([C@@H]1O)O)O)O)OP(OC[C@@H](COC(=O)*)OC(=O)*)(=O)[O-])O 2D coordinates Mol file for the small molecule Search links Involved in 74 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline CMP Identifier CHEBI:60377 Charge -2 Formula C9H12N3O8P InChIKeyhelp_outline IERHLVCPSMICTF-XVFCMESISA-L SMILEShelp_outline Nc1ccn([C@@H]2O[C@H](COP([O-])([O-])=O)[C@@H](O)[C@H]2O)c(=O)n1 2D coordinates Mol file for the small molecule Search links Involved in 166 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline H+ Identifier CHEBI:15378 Charge 1 Formula H InChIKeyhelp_outline GPRLSGONYQIRFK-UHFFFAOYSA-N SMILEShelp_outline [H+] 2D coordinates Mol file for the small molecule Search links Involved in 9,521 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
Cross-references
| RHEA:11580 | RHEA:11581 | RHEA:11582 | RHEA:11583 | |
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| Reaction direction help_outline | undefined | left-to-right | right-to-left | bidirectional |
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Publications
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Identification of rat liver phosphatidylinositol synthase as a 21 kDa protein.
Monaco M.E., Feldman M., Kleinberg D.L.
Substantial purification of rat liver phosphatidylinositol (PtdIns) synthase has been achieved by a combination of Hecameg extraction, heat treatment, affinity chromatography and chromatography on PBE-94. The activity chromatographs as a single peak which has an apparent molecular mass between 150 ... >> More
Substantial purification of rat liver phosphatidylinositol (PtdIns) synthase has been achieved by a combination of Hecameg extraction, heat treatment, affinity chromatography and chromatography on PBE-94. The activity chromatographs as a single peak which has an apparent molecular mass between 150 and 200 kDa on Sepharose 4B. When analysed by SDS/PAGE, two major bands are seen. The enzyme activity is correlated with a protein band of 21 kDa. A second band, at 51 kDa, is eluted from a PBE-94 column slightly ahead of the activity. Manganese is an absolute requirement for stabilization of activity in the presence of detergent. The effect of manganese is optimal at 0.5 mM; magnesium at a concentration of 10 mM is only minimally effective. Substrate Kms are 1.3 mM and 9.5 microM for inositol and CDP-diacylglycerol respectively. The activity eluting from the PBE-94 column is purified 5000-fold over the post-mitochondrial supernatant. << Less
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Identification of AtPIS, a phosphatidylinositol synthase from Arabidopsis.
Collin S., Justin A.-M., Cantrel C., Arondel V., Kader J.-C.
Phosphatidylinositol synthase is the enzyme responsible for the synthesis of phosphatidylinositol, a key phospholipid component of all eukaryotic membranes and the precursor of messenger molecules involved in signal transduction pathways for calcium-dependent responses in the cell. Using the amino ... >> More
Phosphatidylinositol synthase is the enzyme responsible for the synthesis of phosphatidylinositol, a key phospholipid component of all eukaryotic membranes and the precursor of messenger molecules involved in signal transduction pathways for calcium-dependent responses in the cell. Using the amino acid sequence of the yeast enzyme as a probe, we identified an Arabidopsis expressed sequence tag potentially encoding the plant enzyme. Sequencing the entire cDNA confirmed the homology between the two proteins. Functional assays, performed by overexpression of the plant cDNA in Escherichia coli, a bacteria which lacks phosphatidylinositol and phosphatidylinositol synthase activity, showed that the plant protein induced the accumulation of phosphatidylinositol in the bacterial cells. Analysis of the enzymatic activity in vitro showed that synthesis of phosphatidylinositol occurs when CDP-diacylglycerol and myo-inositol only are provided as substrates, that it requires manganese or magnesium ions for activity, and that it is at least in part located to the bacterial membrane fraction. These data allowed us to conclude that the Arabidopsis cDNA codes for a phosphatidylinositol synthase. A single AtPIS genetic locus was found, which we mapped to Arabidopsis chromosome 1. << Less
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Purification and characterization of phosphatidylinositol synthase from human placenta.
Antonsson B.E.
Phosphatidylinositol synthase (CDP-1,2-diacyl-sn-glycerol:myoinositol 3-phosphatidyltransferase, EC 2.7.8.11) was purified from the microsomal fraction of human placenta. The Triton X-100-extracted enzyme was purified 8300-fold over the microsomal fraction by affinity chromatography on CDP-diacylg ... >> More
Phosphatidylinositol synthase (CDP-1,2-diacyl-sn-glycerol:myoinositol 3-phosphatidyltransferase, EC 2.7.8.11) was purified from the microsomal fraction of human placenta. The Triton X-100-extracted enzyme was purified 8300-fold over the microsomal fraction by affinity chromatography on CDP-diacylglycerol-Sepharose followed by ion-exchange chromatography on Mono Q. The purified enzyme had a molecular mass of 24,000 Da on SDS/PAGE. The enzyme had a pH optimum at 9.0, required Mn2+ or Mg2+, and was inhibited by Ca2+ and Zn2+. The Km for myo-inositol was determined to be 0.28 mM. Optimal activity was obtained at 0.2-0.4 mM CDP-diacylglycerol; higher concentrations of the lipid substrate inhibited the enzyme reaction. The enzyme was inhibited by nucleoside di- and tri-phosphates, Pi and PPi. CDP competitively inhibited the enzyme reaction with a Kis of 4 mM. The optimal temperature for the PtdIns synthase reaction was 50 degrees C. << Less
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Regulation by phosphatidylinositol of rat pituitary plasma membrane and endoplasmic reticulum phosphatidylinositol synthase activities. A mechanism for activation of phosphoinositide resynthesis during cell stimulation.
Imai A., Gershengorn M.C.
The mechanism of signal transduction used by a large number of extracellular regulatory molecules involves hydrolysis and resynthesis of phosphoinositides. We recently demonstrated that during stimulation by thyrotropin-releasing hormone of rat pituitary (GH3) cells phosphatidylinositol (PtdIns) r ... >> More
The mechanism of signal transduction used by a large number of extracellular regulatory molecules involves hydrolysis and resynthesis of phosphoinositides. We recently demonstrated that during stimulation by thyrotropin-releasing hormone of rat pituitary (GH3) cells phosphatidylinositol (PtdIns) resynthesis occurs within the plasma membrane as well as the endoplasmic reticulum (Imai, A., and Gershengorn, M. C. (1987) Nature, 325, 726-728). In this report, we have studied regulation of PtdIns synthase (CDP-diglyceride-inositol phosphatidyltransferase, EC 2.7.8.11) activities associated with plasma membranes and endoplasmic reticulum isolated from GH3 cells. Exogenously added PtdIns noncompetitively inhibited membrane-associated and solubilized PtdIns synthase activities by up to 84 to 91%; half-maximal inhibition occurred between 0.03 and 0.1 mM PtdIns. Similar inhibition of PtdIns synthase activities were observed when PtdIns content of both membrane fractions was increased in vivo in intact GH3 cells prior to assay in vitro. These findings demonstrate that PtdIns synthase activities associated with plasma membrane and endoplasmic reticulum fractions isolated from GH3 cells are inhibited by the product, PtdIns. Because PtdIns levels decrease and PtdIns resynthesis is activated in both membrane fractions during stimulation of GH3 cells by thyrotropin-releasing hormone, it seems likely that activation of PtdIns synthase(s) during cell stimulation occurs by release of this enzyme(s) from inhibition by its product. << Less