Phosphatidylcholine is the most abundant phospholipid in mammalian, plant, and yeast cells. It is found mainly in the outer leaflet of cell membranes and can make up approximately half of the total phospholipids. In mammalian tissues, phosphatidylcholine commonly contains a saturated and unsaturated fatty acid at glycerol's C-1 and C-2 positions, respectively. It is a substrate for various enzymes in cell signaling pathways cleaved by phospholipases into diacylglycerol, phosphocholine, phosphatidic acid, and choline. This product contains phosphatidylcholine molecular species with variable fatty acyl chain lengths at the sn-1 and sn-2 positions.
