Diacylglycerol-induced membrane targeting and activation of protein kinase Cε : Mechanistic differences between protein kinases Cδ and Cε

摘要: Two novel protein kinases C (PKC), PKCδ and PKCϵ, have been reported to opposing functions in some mammalian cells. To understand the basis of their distinct cellular regulation, we investigated mechanism vitro sn-1,2-diacylglycerol (DAG)-mediated membrane binding PKCϵ compared it with that PKCδ. The regulatory domains PKC contain a C2 domain tandem repeat C1 (C1A C1B), which identified as interaction site for DAG phorbol ester. Isothermal titration calorimetry surface plasmon resonance measurements showed isolated C1A C1B comparably high affinities Furthermore, activity analyses mutants both play role DAG-induced activation PKCϵ. are not conformationally restricted readily accessible unlike those Consequently, phosphatidylserine-dependent unleashing seen was necessary Cell studies fluorescent protein-tagged PKCs that, due lack lipid headgroup selectivity, translocated plasma nuclear membrane, whereas migrates specifically under conditions is evenly distributed among intracellular membranes HEK293 Also, much faster than conformational flexibility its domains. Collectively, these results provide new insight into differential mechanisms based on different structural functional properties