Publications

• Cloning and expression of a human choline/ethanolaminephosphotransferase: synthesis of phosphatidylcholine and phosphatidylethanolamine.

  Henneberry A.L., McMaster C.R.

  Cholinephosphotransferase catalyses the final step in the synthesis of phosphatidylcholine (PtdCho) via the Kennedy pathway by the transfer of phosphocholine from CDP-choline to diacylglycerol. Ethanolaminephosphotransferase catalyses an analogous reaction with CDP-ethanolamine as the phosphobase ... >> More

  Cholinephosphotransferase catalyses the final step in the synthesis of phosphatidylcholine (PtdCho) via the Kennedy pathway by the transfer of phosphocholine from CDP-choline to diacylglycerol. Ethanolaminephosphotransferase catalyses an analogous reaction with CDP-ethanolamine as the phosphobase donor for the synthesis of phosphatidylethanolamine (PtdEtn). Together these two enzyme activities determine both the site of synthesis and the fatty acyl composition of PtdCho and PtdEtn synthesized de novo. A human choline/ethanolaminephosphotransferase cDNA (hCEPT1) was cloned, expressed and characterized. Northern blot analysis revealed one hCEPT1 2.3 kb transcript that was ubiquitous and not enriched, with respect to actin, in any particular cell type. The open reading frame predicts a protein (hCEPT1p) of 416 amino acid residues with a molecular mass of 46550 Da containing seven membrane-spanning domains. A predicted amphipathic helix resides within the active site of the enzyme with the final two aspartic residues of the CDP-alcohol phosphotransferase motif, DG(X)2AR(X)8G(X)3D(X)3D, positioned within this helix. hCEPT1p was successfully expressed in a full-length, active form in Saccharomyces cerevisiae cells devoid of endogenous cholinephosphotransferase or ethanolaminephosphotransferase activities (HJ091, cpt1::LEU2 ept1-). In vitro, hCEPT1p displayed broad substrate specificity, utilizing both CDP-choline and CDP-ethanolamine as phosphobase donors to a broad range of diacylglycerols, resulting in the synthesis of both PtdCho and PtdEtn. In vivo, S. cerevisiae cells (HJ091, cpt1::LEU2 ept1-) expressing hCEPT1 efficiently incorporated both radiolabelled choline and ethanolamine into phospholipids, demonstrating that hCEPT1p has the ability to synthesize both choline- and ethanolamine- containing phospholipids in vitro and in vivo. << Less

  Biochem. J. 339:291-298(1999) [PubMed] [EuropePMC]

  This publication is cited by 10 other entries.

• sn-1,2-diacylglycerol choline- and ethanolaminephosphotransferases in Saccharomyces cerevisiae. Mixed micellar analysis of the CPT1 and EPT1 gene products.

  Hjelmstad R.H., Bell R.M.

  The Saccharomyces cerevisiae CPT1 and EPT1 genes are structural genes encoding distinct sn-1,2-diacylglycerol choline- and ethanolaminephosphotransferases. A haploid cpt1 ept1 double null mutant lacked detectable choline- and ethanolaminephosphotransferase activity but was viable for growth, estab ... >> More

  The Saccharomyces cerevisiae CPT1 and EPT1 genes are structural genes encoding distinct sn-1,2-diacylglycerol choline- and ethanolaminephosphotransferases. A haploid cpt1 ept1 double null mutant lacked detectable choline- and ethanolaminephosphotransferase activity but was viable for growth, establishing that these enzymes are nonessential. The activities of the CPT1 and EPT1 gene products were independently studied in membranes prepared from strains mutant in the cognate locus using mixed micellar assays. Both enzymes absolutely required phospholipid cofactors; half-maximal activation was observed at low mole fractions, suggesting that a small number of phospholipid molecules are required. The activities of the CPT1 and EPT1 gene products were compared with respect to dioleoylglycerol dependence, CDP-aminoalcohol specificity, phospholipid activation, and inhibition by CMP. The EPT1 gene product utilized CDP-ethanolamine, -monomethylethanolamine, -dimethylethanolamine, and -choline to significant extents, while the CPT1 gene product manifested relative specificity for CDP-choline and -dimethylethanolamine. The CPT1 and EPT1 gene products exhibited differing properties with respect to phospholipid activation, but this difference was dependent on the CDP-aminoalcohol substrate. In contrast, the two enzymes could be distinguished on the basis of their dioleoylglycerol dependencies, activation by Mg2+, and CMP inhibition profiles regardless of the CDP-aminoalcohol substrate employed. These studies provide the first definitive kinetic properties of individual choline- and ethanolaminephosphotransferases. << Less

  J. Biol. Chem. 266:4357-4365(1991) [PubMed] [EuropePMC]

  This publication is cited by 5 other entries.

• Locations and contributions of the phosphotransferases EPT1 and CEPT1 to the biosynthesis of ethanolamine phospholipids.

  Horibata Y., Ando H., Sugimoto H.

  The final step of the CDP-ethanolamine pathway is catalyzed by ethanolamine phosphotransferase 1 (EPT1) and choline/EPT1 (CEPT1). These enzymes are likely involved in the transfer of ethanolamine phosphate from CDP-ethanolamine to lipid acceptors such as 1,2-diacylglycerol (DAG) for PE production ... >> More

  The final step of the CDP-ethanolamine pathway is catalyzed by ethanolamine phosphotransferase 1 (EPT1) and choline/EPT1 (CEPT1). These enzymes are likely involved in the transfer of ethanolamine phosphate from CDP-ethanolamine to lipid acceptors such as 1,2-diacylglycerol (DAG) for PE production and 1-alkyl-2-acyl-glycerol (AAG) for the generation of 1-alkyl-2-acyl-glycerophosphoethanolamine. Here, we investigated the intracellular location and contribution to ethanolamine phospholipid (EP) biosynthesis of EPT1 and CEPT1 in HEK293 cells. Immunohistochemical analyses revealed that EPT1 localizes to the Golgi apparatus and CEPT1 to the ER. We created EPT1-, CEPT1-, and EPTI-CEPT1-deficient cells, and labeling of these cells with radio- or deuterium-labeled ethanolamine disclosed that EPT1 is more important for the de novo biosynthesis of 1-alkenyl-2-acyl-glycerophosphoethanolamine than is CEPT1. EPT1 also contributed to the synthesis of PE species containing the fatty acids 36:1, 36:4, 38:5, 38:4, 38:3, 40:6, 40:5, and 40:4. In contrast, CEPT1 was important for PE formation from shorter fatty acids such as 32:2, 32:1, 34:2, and 34:1. Brefeldin A treatment did not significantly affect the levels of the different PE species, indicating that the subcellular localization of the two enzymes is not responsible for their substrate preferences. In vitro enzymatic analysis revealed that EPT1 prefers AAG 16-20:4 > DAG 18:0-20:4 > DAG 16:0-18:1 = AAG 16-18:1 as lipid acceptors and that CEPT1 greatly prefers DAG 16:0-18:1 to other acceptors. These results suggest that EPT1 and CEPT1 differ in organelle location and are responsible for the biosynthesis of distinct EP species. << Less

  J Lipid Res 61:1221-1231(2020) [PubMed] [EuropePMC]

  This publication is cited by 5 other entries.