A novel intracellular membrane-bound calcium-independent phospholipase A(2)

We have cloned human cDNA encoding a novel protein of 782 amino acids that contains the lipase consensus sequence Gly-Xaa-Ser-Xaa-Gly and several stre tches surrounding the motif, which are homologous to those of the catalytic domain of cytosolic calcium-independent phospholipase A(2) (iPLA(2)). When expressed in COS-7 cells, the protein predominantly exists in the membrane fraction and exhibits a phospholipase A(2) activity in a calcium-independe nt manner. The transcript of the membrane-bound iPLA(2) gene is ubiquitousl y observed as a single band of approximately 3.3 kb on Northern blot, with the most abundant expression in the skeletal muscle and heart. By a search of the database, we have also identified its putative C. elegans homologue, which shows 47% identity with that of human in the iPLA(2) catalytic regio n. Thus the novel type of iPLA(2) is evolutionarily well conserved, suggest ive of its biological significance. (C) 2000 Academic Press.