Oil biosynthesis in microsomal membrane preparations from Mortierella alpina

Microsomal membrane preparations from Mortierella alpina catalysed the conv ersion of sn-glycerol 3-phosphate and [C-14]oleoyl-CoA to radioactive phosp hatidic acid, diacylglycerol and triacylglycerol, Experiments with lysophos phatidic acid and [14C]oleoyl-CoA gave a similar pattern of radioactivity i n the complex lipids. The specific activity of lysophosphatidate acyltransf erase was almost eight times greater than sn-glycerol-3-phosphate acyltrans ferase, indicating that the first acylation step was limiting in oil assemb ly in the microsomal membranes. Little conversion of radioactive oleate int o phosphatidylcholine occurred, suggesting that triacylglycerol assembly an d its relationship to phosphatidylcholine metabolism differed to that found in oilseeds.