Parthasarathy S, Murari R, Crilly K S, Baumann W J
Biochim Biophys Acta. 1981 May 22;664(2):249-54. doi: 10.1016/0005-2760(81)90047-3.
Acyl-CoA : 1,2-diacylglycerol O-acyltransferase (EC 2.3.1.20) activity of rat liver microsomes was found to be stimulated by 1-acyl-sn-glycero-3-phosphocholine at low concentrations, but was inhibited above 0.2 mM. Diacylglycerol acylation was optimal at 75 microM lysophosphatidylcholine, resulting in a more than 2-fold activation of the enzyme. Acyltransferase activity disappeared above 0.5 mM lysophosphatidylcholine levels. 0.05% sodium taurocholate supplementation reduced diacylglycerol acyltransferase activity by approx. 2/3 over the entire range of lysophosphatidylcholine concentrations. 1-O-Hexadecylpropanediol-3-phosphocholine was shown to mimic lysophosphatidylcholine at stimulatory and at inhibitory concentrations in the absence and in the presence of sodium taurocholate, thus ruling out acyl-CoA depletion due to lysophosphatidylcholine acylation as a cause of depressed triacylglycerol synthesis at higher lysophosphatidylcholine levels. 1-Acyl-sn-glycero-3-phosphoethanolamine stimulated diacylglycerol acyltransferase to a lesser extent, without showing inhibition at higher concentrations. The data point towards a direct effect of the lysophospholipids on the acyltransferase system.
