GEORGE CARMAN

..In addition to the regulation of gene expression, phosphorylation of key phospholipid synthesis catalytic and regulatory proteins controls the metabolism of phospholipid precursors and products...

..Phosphorylation of CTP synthetase with protein kinases A and C together resulted in an increase in CTP synthetase activity that was slightly greater than that obtained when the enzyme was phosphorylated with either protein kinase alone...

..With molecular information now available for both types of PAP, the specific roles of these enzymes in lipid metabolism are being clarified...

..This regulation may play an important role in allowing cells to adapt to zinc deficiency given the essential roles that phospholipids play in the structure and function of cellular membranes...

..Regulation of phospholipid synthesis may provide an important mechanism by which cells cope with the stress of zinc depletion, given the roles that phospholipids play in the structure and function of cellular membranes...

..Phosphatidic acid, whose levels are controlled by the biochemical regulation of key phospholipid synthesis enzymes, plays a central role in the regulation of phospholipid synthesis gene expression...

..Pure DGPP phosphatase from Saccharomyces cerevisiae was shown to be similar to the E. coli DGPP phosphatase in its ability to utilize lyso-PA and phosphatidylglycerophosphate as substrates in vitro...

..Rat liver PAP2 displays diacylglycerol pyrophosphate phosphatase activity...

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..These data supported the conclusion that phosphorylation of Opi1p at Ser31 and Ser251 mediated the stimulation of the negative regulatory function of Opi1p on the expression of the INO1 gene...

..These data supported the conclusion that casein kinase II phosphorylation at Ser10 played a role in stimulating the repression of INO1 when Opi1p was not in its most active state (i.e. in inositol-deprived cells)...

..These results indicated that a decrease in the cytoplasmic levels of zinc was responsible for the alterations in phospholipid composition...

..These results indicate that phosphatidylserine synthase is phosphorylated on Ser(46) and Ser(47) by protein kinase A, which results in a higher amount of enzyme for the net effect of stimulating the synthesis of phosphatidylserine...

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..CTP synthetase and Opi1p are also phosphorylated by protein kinase C. The phosphorylation of these proteins plays a role in regulating their activities and (or) function in phospholipid synthesis...

..These results revealed a novel mechanism that controls phospholipid synthesis in yeast...

..This work suggested that diacylglycerol pyrophosphate phosphatase functions to regulate the levels of diacylglycerol pyrophosphate and phosphatidate on the cytosolic face of the vacuole membrane...

..The induction of CKI1 expression in zinc-depleted cells translated into increased choline kinase activity in vitro and in vivo, and an increase in phosphatidylcholine synthesis via the Kennedy pathway...

..The expression in yeast has revealed that the human CTPS1-encoded enzyme is also phosphorylated and regulated by protein kinases A and C...

..Mutations that decrease phosphatidate levels decrease nuclear membrane growth in pah1Delta cells. We propose that phosphatidate metabolism is a critical factor determining nuclear structure by regulating nuclear membrane biogenesis...

..This work advances our understanding of phosphatidylserine synthase regulation and underscores the importance of mitochondrial respiration to the regulation of phospholipid synthesis in S. cerevisiae...

..G., and Carman, G.M. (2006) J. Biol. Chem. 282, 5367-5377). These data indicated that protein kinase C phosphorylation at Ser(462) stimulates human CTP synthetase 1 activity, whereas phosphorylation at Thr(455) inhibits activity...

..These results demonstrated that the PAP1 activity of the PAH1 gene product is essential for its roles in lipid metabolism and cell physiology...

..The properties of the DPP1-encoded and LPP1-encoded lipid phosphate phosphatase enzymes are summarized...

..Taken together, this work demonstrated that the zinc-mediated regulation of ethanolamine kinase and the synthesis of phospholipids via the CDP-ethanolamine branch of the Kennedy pathway were controlled in part by Zap1p...

..Heterologous expression of human LPIN1 in E. coli showed that lipin 1 is also a Mg(2+)-dependent PA phosphatase enzyme...

..The alterations in CTP levels correlated with the regulatory effects CTP has on the pathways responsible for the synthesis of the membrane phospholipid phosphatidylcholine...

..The repression of ethanolamine kinase by inositol supplementation correlated with a decrease in the incorporation of ethanolamine into CDP-ethanolamine pathway intermediates and into phosphatidylethanolamine and phosphatidylcholine...

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..Regulation of DPP1 correlates with the expression of DGPP phosphatase activity and the cellular levels of DGPP and PA...

..These studies showed that S. cerevisiae was useful for the analysis of human CTP synthetase phosphorylation...

..This work advances understanding of phospholipid synthesis regulation by zinc and the transcription control of the PIS1 gene...

..These activities are measured by following the release of water-soluble radioactive inorganic phosphate from chloroform-soluble radioactive lipid phosphate substrate following a simple chloroform/methanol/ water phase partition...

..Comparison of phosphopeptide maps of the wild type and S30A mutant choline kinase enzymes phosphorylated by protein kinase C confirmed that Ser30 was also a target site for protein kinase C...

..Pure enzyme and a water-soluble phosphatidate substrate were required for the assay, which should be applicable to a well-defined large-scale screen of Mg2(+)-dependent phosphatidate phosphatise inhibitors (or activators)...

..4 mm) and competitive inhibitor (apparent K(i) = 0.4 mm) of the enzyme. Diacylglycerol kinase activity was stimulated by major membrane phospholipids and was inhibited by CDP-diacylglycerol and sphingoid bases...

..cerevisiae cells, and this was accompanied by a 2.5-fold increase in the cellular concentration of CTP and a 1.5-fold increase in the choline-dependent synthesis of phosphatidylcholine...

..cerevisiae...

..These data supported the conclusion that phosphorylation of choline kinase on Ser(30) and Ser(85) by protein kinase A regulates PC synthesis by the CDP-choline pathway...

..2, 15.5, and 18.5 kcal/mol, respectively. The isoform activities were dependent on PA as a substrate and required at least one unsaturated fatty acyl moiety for maximum activity...

..We also provide evidence that derepression of phospholipid biosynthetic genes is not sufficient to induce the nuclear membrane expansion shown in the pah1delta cells...

..Lsb6 therefore is a novel regulator of Las17 that mediates endosome motility independent of phosphatidylinositol 4-phosphate synthesis. Mammalian type II phosphatidylinositol 4-kinases may regulate WASp proteins and endosome motility...

..These data support a model in which the increased activity of the mutant ATPase upon acid addition depletes the cells' supply of ATP, resulting in cell death...

..Our results therefore reveal a surprising role for PA in Schwann cell fate determination and provide evidence of a direct link between diseases affecting lipid metabolism and abnormal Schwann cell function...

..Zinc transport function will be addressed with mutants defective in phospholipid synthesis, and with Zrtlp reconstituted into unilamellar vesicles with varying phospholipid composition. ..

..The regulation of PA kinase expression and activity will also be examined. PA kinase will be purified and characterized, and the regulation of activity by phospholipids and water-soluble metabolites will be investigated. ..

..The regulation of phospho lipid synthesis by phosphorylation will be examined in a CTP synthetase mutant defective in CTP product inhibition and in mutants defective in the RASIcAMP pathway. ..

..cerevisiae. The results of these studies should be relevant to higher eukaryotic organisms. ..

..Moreover, unregulated lipid synthesis, as mediated by the PAP1 enzyme, may cause metabolic disorders such as insulin resistance, diabetes, and heart disease. ..

..Zinc transport function will be addressed with mutants defective in phospholipid synthesis, and with Zrt1p reconstituted into unilamellar vesicles with varying phospholipid composition. ..

..Zinc transport function will be addressed with mutants defective in phospholipid synthesis, and with Zrt1p reconstituted into unilamellar vesicles with varying phospholipid composition. ..

..The mechanism for CHO1 mRNA (a CDP-diacylgylcerol pathway transcript) degradation will be examined. ..

..This work should also be relevant to other aspects of macromolecular synthesis that are dependent on CTP as a precursor. ..

..Enzyme regulation will also be studied in clones containing the structural genes encoding for these enzymes. The results found with S. cerevisiae should be relevant to higher eucaryotic organisms...

..The essential nature of PA phosphatase will also be addressed. The results of the proposed studies with S. cerevisiae should be relevant to higher eukaryotic organisms...