title: Utilization of endogenous diacylglycerol for the synthesis of triacylglycerol, phosphatidylcholine and phosphatidylethanolamine by lipid particles from baker's yeast (Saccharomyces cerevisiae).
abstract: The activity of the enzymes diacylglycerol acyltransferase (EC 2.3.1.20), cholinephosphotransferase (EC 2.7.8.2) and ethanolaminephosphotransferase (EC 2.7.8.1) have been measured in a lipid particle preparation from baker's yeast (Saccharomyces cerevisiae) with endogenous 1,2-diacylglycerol as substrate. For all three enzymes the rate of diacylglycerol utilization was established with respect to substrate and Mg2+ concentration. Neither of the enzyme activities was stimulated significantly by addition of diacylglycerols. The conversion of diacylglycerol into triacylglycerol in the presence of CDP-choline and CDPethanolamine, and the synthesis of phospholipids in the presence of acyl-CoA either added or generated in situ were studied. Neither CDPcholine nor CDPethanolamine had an effect on triacylglycerol synthesis. Exogenous acyl-CoA had no effect on either choline- or ethanolaminephosphotransferase activity. However, when the necessary substrates for formation of acyl-CoAs in situ (ATP, CoA, Mg2+ and free fatty acids) were added a decrease in both cholinephosphotransferase and ethanolaminephosphotransferase activity was observed. This inhibition was shown to be due to ATP and might explained as a result of chelation of the Mg2+, a necessary activator of both the choline- and the ethanolaminephosphotransferase.
mesh_terms: D000105:Acetyl Coenzyme A / Q000494:pharmacology; D000217:Acyltransferases / Q000378:metabolism; D003565:Cytidine Diphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D003566:Cytidine Diphosphate Choline / Q000494:pharmacology; D002798:Diacylglycerol Cholinephosphotransferase / Q000378:metabolism; D004075:Diglycerides / Q000378:metabolism*; D004982:Ethanolaminephosphotransferase / Q000378:metabolism; D004983:Ethanolamines / Q000494:pharmacology; D005989:Glycerides / Q000378:metabolism*; D008861:Microsomes / Q000378:metabolism*; D010713:Phosphatidylcholines / Q000096:biosynthesis*; D010714:Phosphatidylethanolamines / Q000096:biosynthesis*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D014280:Triglycerides / Q000096:biosynthesis*
chemical_list: D004075:Diglycerides; D004983:Ethanolamines; D005989:Glycerides; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D014280:Triglycerides; D003566:Cytidine Diphosphate Choline; D003565:Cytidine Diphosphate; D000105:Acetyl Coenzyme A; D000217:Acyltransferases; D004982:Ethanolaminephosphotransferase; D002798:Diacylglycerol Cholinephosphotransferase