Comparative studies of CDP-diacylglycerol synthase in rat liver mitochondria and microsomes.
CDP-diacylglycerol for polyglycerophosphatide biogenesis can be synthesized within rat liver mitochondria. Contamination by microsomal membranes cannot account for the CDP-diacylglycerol synthesis found in the mitochondria. Phosphatidic acid from egg lecithin was the best substrate for the synthesis of CDP-diacylglycerol in both subcellular fractions. Concentration curves for CTP and Mg2+ differed for the two subcellular fractions. Microsomal CDP-diacylglycerol synthase was specifically stimulated by the nucleotide GTP; this stimulatory effect by GTP was not observed in the mitochondrial fraction. By comparison, the microsomal enzyme was more sensitive towards sulfhydryl inhibitors than the mitochondrial enzyme. The enzymes could be solubilized from the membrane fractions using 3-[(cholamidopropyl)dimethylammonio]-1-propanesulfonate, and the detergent-soluble activity could be partially restored by addition of phospholipids. Based on the differences in properties, it was concluded that there are two distinct enzyme localizations for CDP-diacylglycerol synthesis in mitochondria and microsomes from rat liver.
University of Western Ontario, Department of Biochemistry, London, Canada.
A Y
AY
Mok
G E
GE
McDougall
W C
WC
McMurray
D000818:Animals; D002451:Cell Compartmentation; D003567:Cytidine Diphosphate Diglycerides / Q000096:biosynthesis; D002798:Diacylglycerol Cholinephosphotransferase / Q000032:analysis / Q000302:isolation & purification / Q000378:metabolism*; D004655:Emulsions; D004793:Enzyme Reactivators; D005227:Fatty Acids / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D008862:Microsomes, Liver / Q000201:enzymology / Q000378:metabolism*; D008930:Mitochondria, Liver / Q000201:enzymology / Q000378:metabolism*; D009711:Nucleotides / Q000378:metabolism; D010712:Phosphatidic Acids / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013347:Subcellular Fractions / Q000201:enzymology; D013379:Substrate Specificity; D013439:Sulfhydryl Reagents
D003567:Cytidine Diphosphate Diglycerides; D004655:Emulsions; D004793:Enzyme Reactivators; D005227:Fatty Acids; D008565:Membrane Proteins; D009711:Nucleotides; D010712:Phosphatidic Acids; D010743:Phospholipids; D013439:Sulfhydryl Reagents; D006160:Guanosine Triphosphate; D002798:Diacylglycerol Cholinephosphotransferase