Human acylation stimulating protein enhances triacylglycerol biosynthesis in plant microsomes

Diacylglycerol acyltransferase has a universal role in catalyzing the acyl- CoA-dependent formation of triacylglycerol in microorganisms, animals and p lants. Acylation stimulating protein, from human blood, is known to enhance diacylglycerol acyltransferase activity and triacylglycerol biosynthesis i n human adipocytes, In the current study, acylation stimulating protein was also shown to enhance diacylglycerol acyltransferase activity in microsome s from cell suspension cultures of oilseed rape. Enzyme stimulation occurre d over the pH range of 6-9 but the degree of stimulation decreased with inc reasing ionic strength at pH 7.4. Varying acyl-CoA concentration did not af fect the degree of stimulation. Membranes from triacylglycerol producing ce lls in plants and humans may have similar binding sites for acylation stimu lating protein which have been preserved during molecular evolution. The re sults suggest that human acylation stimulating protein may be useful in mod ifying lipid biosynthesis in plants. (C) 2000 Federation of European Bioche mical Societies, Published by Elsevier Science B.V. All rights reserved.