Updating Phospholipase [A.sub.2] Biology

The phospholipase [A.sub.2] ([PLA.sub.2]) superfamily contains more than 50 enzymes in mammals that are subdivided into several distinct families on a structural and biochemical basis. In principle, [PLA.sub.2] has the capacity to hydrolyze the sn-2 position of glycerophospholipids to release fatty acids and lysophospholipids, yet several enzymes in this superfamily catalyze other reactions rather than or in addition to the [PLA.sub.2] reaction. [PLA.sub.2] enzymes play crucial roles in not only the production of lipid mediators, but also membrane remodeling, bioenergetics, and body surface barrier, thereby participating in a number of biological events. Accordingly, disturbance of [PLA.sub.2]-regulated lipid metabolism is often associated with various diseases. This review updates the current state of understanding of the classification, enzymatic properties, and biological functions of various enzymes belonging to the [PLA.sub.2] superfamily, focusing particularly on the novel roles of [PLA.sub.2]s in vivo.