Evidence for a compartmentation of brain microsomal diacylglycerol

Phosphatidylcholine synthesis from CDP-[methyl-14C]choline and membrane-bound diacyl-[U-14C]-sn-glycerol, formed through the glycerol phosphate pathway, has been examined in vitro in rat brain microsomes. When labeled diacylglycerol was incubated in the presence of unlabeled CDP-choline, the rate of phospholipid labeling looked very different from that measured in incubations of unlabeled diacylglycerol with CDP-[methyl-14C]choline. Evidence is given that diacylglycerol formed through the glycerol phosphate pathway belongs to a metabolic pool separate from the bulk membrane diacylglycerol.