12Diacylglycerol

12diacylglycerol, commonly referred to as 1,2-diacyl-sn-glycerol, is a diacylglycerol lipid in which two fatty acids are esterified at the sn-1 and sn-2 positions of glycerol, leaving a free hydroxyl group at sn-3. The two acyl chains can vary widely in length and degree of saturation, producing a broad range of DAG species that are amphiphilic and largely embedded in lipid membranes.

Biosynthesis and metabolism: DAG arises during the hydrolysis of glycerolipids. It is produced by phospholipase C cleavage of phosphatidylinositol bisphosphate (PIP2) yielding DAG and IP3; it is also generated by triglyceride lipolysis. DAG can be acylated to form phosphatidic acid via DAG kinase, or hydrolyzed to monoacylglycerol by DAG lipase.

Biological roles: In cells, DAG is a key second messenger that recruits and activates protein kinase C and certain other signaling proteins at membrane surfaces. Its signaling outcome depends on DAG localization, acyl-chain composition, and the presence of calcium.

Distribution and significance: DAG species are found in membranes and lipid droplets; the relative abundance and composition influence membrane curvature and protein interactions. In research, synthetic DAGs with defined acyl chains are used to study PKC activation and lipid signaling pathways.