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.