Identification of hepatic peroxisomal phospholipase A₂ and characterization of arachidonic acid-containing choline glycerophospholipids in hepatic peroxisomes

Recently, a sequence encoding a novel mammalian calcium-independent phospholipase A₂ (iPLA₂γ) was identified in the human genome and subsequently cloned and expressed in Sf9 insect cells. Unexpectedly, expression studies in recombinant systems demonstrated the usage of multiple translation initiation codons resulting in different polypeptides. Herein, we demonstrate that hepatic iPLA₂γ is localized to rat liver peroxisomes, possesses a molecular mass of 63 kDa and that peroxisomal membranes are highly enriched in arachidonic acid-containing phospholipids. Collectively, these results provide the first demonstration of iPLA₂γ in mammalian tissue and suggest the possibility that iPLA₂γ can contribute to lipid second messenger generation by hydrolysis of peroxisomal arachidonic acid-containing phospholipids.