13diacylglycerol

1,3-Diacylglycerol, commonly abbreviated as 1,3-DAG, is a diacylglycerol in which fatty acyl chains are esterified to the sn-1 and sn-3 positions of the glycerol backbone, leaving a free hydroxyl group at the sn-2 position. This isomer differs from 1,2-diacylglycerol, which has the fatty acids on the 1 and 2 positions. In natural lipids, 1,2-DAG is more prevalent in membranes, while 1,3-DAG occurs as a minor component and can be generated by partial hydrolysis or specific enzymatic pathways.

DAG molecules are amphipathic lipids that reside at membranes and play roles in signaling and metabolism. Diacylglycerol acts as a second messenger in various signal transduction pathways, most notably by activating protein kinase C (PKC) isoforms when produced at the plasma membrane. The efficiency of PKC activation depends on the fatty acyl composition and the DAG isomeric form, with 1,2-DAG often emphasized in canonical PKC signaling contexts. Beyond signaling, DAG serves as an intermediate in lipid metabolism, formed during the hydrolysis of phospholipids or triglycerides and subsequently metabolized by DAG lipases or re-esterified into other glycerolipids.

In addition to its physiological roles, 1,3-DAG is studied as a dietary fat. Oils composed predominantly of 1,3-DAG have been marketed as structured lipids with potential reduced caloric absorption and effects on body weight, though clinical evidence is mixed and regulatory status varies by region. Researchers use 1,3-DAG in lipidomics and synthetic chemistry to explore isomer-specific properties and reactions.

Overall, 1,3-diacylglycerol is a distinct isomer of DAG with relevance to signaling, metabolism, and nutritional science, distinguished by its 1,3-positioned fatty acyls on the glycerol backbone.