 There are 4 classes, which are separated by the type of reaction they catalyze.In particular, phospholipase A1 (PLA1) specifically catalyzes the cleavage at the SN-1 position of phospholipids, forming a fatty acid and a lysophospholipid.PLA1's are present in numerous species including humans, and have a variety of cellular functions that include regulation and facilitation of the production of lysophospholipid mediators, and acting as digestive enzymes.