Glycerophospholipid structure. Typical glycerophospholipids consist of a glycerol backbone, two acyl moieties, and a phospho(di)ester headgroup. Arrows indicate the sites of phospholipase-mediated hydrolysis. (PLA, phospholipase A; PLC, phospholipase C; PLD, phospholipase D; PA, phosphatidic acid; PC, phosphatidylcholine; PE, phosphatidylethanolamine; PS, phosphatidylserine; PG, phosphatidylglycerol; PI, phosphatidylinositol; PIP, PI monophosphate; PIP2, PI bisphosphate; PIP3, PI trisphosphate.)