Group IVC cytosolic phospholipase A2γ is farnesylated and palmitoylated in mammalian cells

Abstract

Cytosolic phospholipase A2γ (cPLA2γ) is a member of the group IV family of intracellular phospholipase A2 enzymes, but unlike the well-studied cPLA2α, it is constitutively bound to membrane and is calcium independent. cPLA 2γ contains a C-terminal CaaX sequence and is radiolabeled by mevalonic acid when expressed in cPLA2α-deficient immortalized lung fibroblasts (IMLF-/-). The radiolabel associated with cPLA 2γ was identified as the farnesyl group. The protein farnesyltransferase inhibitor BMS-214662 prevented the incorporation of [ 3H]mevalonic acid into cPLA2γ and partially suppressed serum-stimulated arachidonic acid release from IMLF-/- and undifferentiated human skeletal muscle (SkMc) cells overexpressing cPLA 2γ, but not from cells overexpressing cPLA2α. However, BMS-214662 did not alter the amount of cPLA2γ associated with membrane. DB These results were consistent in COS cells expressing the C538S cPLA2γ prenylation mutant. cPLA 2γ also contains a classic myristoylation site and several potential palmitoylation sites and was found to be acylated with oleic and palmitic acids but not myristoylated. Immunofluorescence microscopy revealed that cPLA2γ is associated with mitochondria in IMLF -/-, SkMc cells, and COS cells. Copyright © 2005 by the American Society for Biochemistry and Molecular Biology, Inc.