Separate myocardial ethanolamine phosphotransferase activities responsible for plasmenylethanolamine and phosphatidylethanolamine synthesis.
Ethanolamine phosphotransferase (EPT) is a key enzyme responsible for the synthesis of ethanolamine glycerophospholipids. Plasmenylethanolamine is a predominant molecular subclass of ethanolamine glycerophospholipids in the heart. The present study was designed to identify the selective use of 1-O-alk-1'-enyl-2-acyl-sn-glycerol as a substrate for EPT as a mechanism responsible for the predominance of plasmenylethanolamine in the rabbit heart. EPT activity in rabbit myocardial membranes using 1,2-diacyl-sn-glycerol as substrate is activated by Mn2+, inhibited by dithiobisnitrobenzoic acid (DTNB) and is unaffected by Ca2+. In contrast, ethanolamine phosphotransferase activity using 1-O-alk-1'-enyl-2-acyl-sn-glycerol as substrate is inhibited by Mn2+ and Ca2+, but is activated by DTNB. Additionally, ethanolamine phosphotransferase activity using 1-O-alk-1'-enyl-2-acyl-sn-glycerol substrate was more sensitive to thermal denaturation compared with that of 1,2-diacyl-sn-glycerol. Taken together, these results suggest that separate ethanolamine phosphotransferase activities are present in heart membranes that are responsible for the synthesis of phosphatidylethanolamine and plasmenylethanolamine.
Ford
David A
DA
Department of Biochemistry and Molecular Biology, St. Louis University Health Sciences Center, St. Louis, MO 63104, USA. fordda@slu.edu
D000818:Animals; D002413:Cations, Divalent / Q000494:pharmacology; D004075:Diglycerides / Q000378:metabolism; D004982:Ethanolaminephosphotransferase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008297:Male; D008823:Micelles; D009206:Myocardium / Q000201:enzymology*; D017830:Octoxynol; D010714:Phosphatidylethanolamines / Q000096:biosynthesis / Q000378:metabolism*; D010955:Plasmalogens / Q000096:biosynthesis / Q000378:metabolism*; D011817:Rabbits
D002413:Cations, Divalent; D004075:Diglycerides; D008823:Micelles; D010714:Phosphatidylethanolamines; D010955:Plasmalogens; C020791:phosphatidal ethanolamines; C035561:diarachidonyl diglyceride; D017830:Octoxynol; D004982:Ethanolaminephosphotransferase