Regulation of hematopoietic-specific G-protein G?15 and G?16 by protein kinase C

Authors:
Publisher website
Google Scholar
Abstract
Heterotrimeric G proteins mediate cell growth and differentiation by coupling cell surface receptors to intracellular effector enzymes. The G‐protein α subunit, Gα16, and its murine homologue Gα15, are expressed specifically in hematopoietic cells and their expression is highly regulated during differentiation of normal and leukemic cells. In this study, we examined the phosphorylation of Gα15/Gα16 and its role in receptor and effector coupling. We observed a PMA‐stimulated intact cell phosphorylation of Gα15 in COS7 cells transfected with Gα15 and protein kinase Cα (PKCα), and phosphorylation of endogenous Gα16 in HL60 cells. We also showed that peptides derived from the two G‐proteins were phosphorylated in vitro using purified brain PKC. Furthermore, we identified the putative phosphorylation site and showed that mutation or deletion of this PKC phosphorylation site inhibited phospholipase C (PLC) activation. The behavior of double mutants with the constitutively active G‐protein mutation (QL‐mutant) and mutation in the putative phosphorylation site suggests that the phosphorylation site of Gα15/16 is essential for receptor‐coupled activation of PLC, but not for direct interaction of the G‐protein with PLC‐β. J. Cell. Biochem. 88: 1101–1111, 2003.

This publication has 30 references indexed in Scilit: