High Quality Content by WIKIPEDIA articles! Phosphatidic acid (PA) is the acid form of phosphatidate, a part of common phospholipids, major constituents of cell membranes. Phosphatidic acid is the simplest diacyl-glycerophospholipid. Phosphatidic acid consists of a glycerol backbone, with, in general, a saturated fatty acid bonded to carbon-1, an unsaturated fatty acid bonded to carbon-2, and a phosphate group bonded to carbon-3. PA is degraded by conversion into DAG by lipid phosphate phosphohydrolases (LPPs) or into lyso-PA by phospholipase A (PLA).