Molecular characterization of cytosolic phospholipase A2-beta.

We have isolated a cDNA encoding a 1012-amino acid polypeptide cPLA2-beta, that has significant homology with cPLA2-alpha in both the calcium-dependent lipid binding domain as well as in the catalytic domain. Transient expression of cPLA2-beta cDNA in COS cells results in an increase in calcium-dependent phospholipase A1 (PLA1) and PLA2 activities compared with vector-transfected cells. cPLA2-beta is markedly less selective for cleavage at sn-2 as compared with cPLA2-alpha and cPLA2-gamma. Northern analysis reveals a cPLA2-beta transcript of 8 kilobase pairs that is expressed in all the human tissues examined. With the identification of cPLA2-beta, the newly defined cPLA2 family now comprises three members that may have dramatically different mechanisms for regulation of expression and enzymatic activation.