title: Production of 1,2-diacylglycerol in human erythrocyte membranes exposed to low concentrations of calcium ions.
abstract: A specific increase in the membrane content of 1,2-diacylglycerol occurred when erythrocytes were lysed at 20 degrees C in media which did not inclued a chelator of Ca2+ and also when Ca2+ was added to haemoglobin-free erythrocyte ghosts which had been prepared in the presence of ethyleneglycol-bis-(beta-aminoethylether)-N,N'-tetraacetic acid (EGTA). The maximum increase was about 20-fold. The production of 1,2-diacylglycerol appeared to be caused by an endogenous membrane-bound phospholipase C which was half-maximally activated at less than 1 muM Ca2+ and which had access to only about 0.6-0.8% of the cells' glycerolipids. This activity was optimal at pH 7.0-7.2 in the presence of 0.1 mM Ca2+; under these conditions diacylglycerol production was complete within 5-10 min. Enzyme activity was markedly decreased at low temperatures, and was abolished by heating at 100 degrees C for 1 min.
mesh_terms: D002118:Calcium / Q000494:pharmacology*; D004075:Diglycerides / Q000096:biosynthesis / Q000097:blood*; D004533:Egtazic Acid / Q000494:pharmacology; D004910:Erythrocyte Membrane / Q000187:drug effects / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism*; D005989:Glycerides / Q000097:blood*; D006801:Humans; D007700:Kinetics; D008563:Membrane Lipids / Q000097:blood; D010713:Phosphatidylcholines / Q000097:blood
chemical_list: D004075:Diglycerides; D005989:Glycerides; D008563:Membrane Lipids; D010713:Phosphatidylcholines; D004533:Egtazic Acid; D002118:Calcium