Phospholipase A

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Phospholipases A2 (PLA2s) (PDB 1CJY, EC 3.1.1.4) are a large family of enzymes that specifically deacylate fatty acids from the 2nd carbon atom (sn2, thus PLA2) of the triglyceride backbone of phospholipids, producing a free fatty acid and a lyso-phospholipid. A large range of fatty acids can be bound to the sn2 position of phospohlipids, including arachidonic acid and eicosapentaenoic acid.

Arachidonic acid is both a signalling molecule and the precursor for other signalling molecules termed eicosanoids. These include leukotrienes and prostaglandins. Some eicosanoids are synthesized from diacylglycerol, released from the lipid bilayer by phospholipase C (see below).

Phospholipases A2 are ubiquitous enzymes, though the individual enzymes expression patterns differ dramatically. Initially, phospholipases A2 were named based on location of activity (e.g. pancreatic and secretory) or mode of activity (calcium dependent and calcium independent). A much more structured and accurate system has been developed based on genetic homology. For reference see (Six DA, Dennis EA. The expanding superfamily of phospholipase A(2) enzymes: classification and characterization. Biochimica et Biophysica Acta. 2000;1488(1-2):1-19).