Biosynthesis of sphingomyelin from erythro-ceramides and phosphatidylcholine by a microsomal cholinephosphotransferase.
Mouse liver microsomes were shown to be active in the synthesis of sphingomyelin from ceramide and phosphatidylcholine in a reaction independent of CDPcholine. The conversion was not inhibited by calcium chelating reagents, and no evidence for the involvement of phospholipase C activity in the transformation could be adduced. Activity was also demonstrated in monkey liver and heart microsomes. Mouse brain microsomes produced a sphingomyelin analogue, tentatively identified as ceramide phosphorylethanolamine, but not sphingomyelin. Both [14C]ceramide and [G-14]phosphatidylethanolamine were precursors of the brain product, while phosphatidylcholine was inactive. Progress in the partial characterization of the liver enzyme is also described.
D000818:Animals; D001921:Brain / Q000378:metabolism; D002118:Calcium / Q000494:pharmacology; D002518:Ceramides / Q000378:metabolism*; D002798:Diacylglycerol Cholinephosphotransferase / Q000378:metabolism*; D004533:Egtazic Acid / Q000494:pharmacology; D008253:Macaca mulatta; D051379:Mice; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology*; D010713:Phosphatidylcholines / Q000378:metabolism*; D010770:Phosphotransferases / Q000378:metabolism*; D012995:Solubility; D013109:Sphingomyelins / Q000096:biosynthesis*
D002518:Ceramides; D010713:Phosphatidylcholines; D013109:Sphingomyelins; D004533:Egtazic Acid; D010770:Phosphotransferases; D002798:Diacylglycerol Cholinephosphotransferase; D002118:Calcium