Phospholipases A(2)

Mammalian cells contain multiple structurally different phospholipase A(2) enzymes that hydrolyse sn-2 fatty acid from membrane phospholipid. The low molecular weight secreted forms act extracellularly both as lipolytic enzymes and as agonists that bind to specific cell surface receptors. The 85 kDa cytosolic phospholipase A(2) plays an important role in mediating agonist-induced arachidonic acid release for eicosanoid production. It is subject to complex mechanisms of activation both transcriptionally and post-translationally. Several cytosolic forms of calcium-independent phospholipases A(2) have been purified and have diverse functions such as mediating basal fatty acyl turnover or inducing membrane alterations during ischemia. These distinct enzymes provide alternative pathways for regulating phospholipid metabolism.