Diglyceride; glycerol with two esterified acyl moieties, either 1,3-diacylglycerol or 1,2-diacylglycerol; if the two acyl groups are nonidentical, there are four possible isomers of 1,2-diacylglycerol; 1,2-diacylglycerol is an intermediate in the synthesis of triacylglycerols and of lecithin; also serves as a second messenger in stimulating the activity of protein kinase C.