Characterization of PDK2 activity against protein kinase B gamma.

摘要: Protein kinase B (PKB), also known as Akt, is a serine/threonine protein controlled by insulin, various growth factors, and phosphatidylinositol 3-kinase. Full activation of the PKB enzyme requires phosphorylation threonine in loop serine C-terminal tail. PDK1 has clearly been shown to phosphorylate threonine, but mechanism leading of the serine, PDK2 site, unclear. A yeast two-hybrid screen using full-length human PKBc identified protein C (PKC) u, an atypical PKC, interactor with PKBc, association requiring the pleckstrin homology domain PKBc. Endogenous was associate endogenous PKCu both cos-1 cells 3T3-L1 adipocytes, demonstrating physiological interaction. Immunoprecipitates of PKCu, whether PKCu from insulin-stimulated adipocytes or overexpressed PKCu from cells, phosphorylated S472 (the site) vitro. In vivo, overexpression stimulated approximately 50% PKBc molecules, suggesting physiologically meaningful effect. However, pure incapable of phosphorylating Antisense knockout studies use PDK1 inhibitor showed that neither autophosphorylation nor by accounted for phosphorylation in immunoprecipitates. Staurosporine inhibited activity not in PKCu Together these results indicate that independent exists that physically associates binding functions deliver a required location. thus adaptor, associating staurosporine-insensitive PDK2 enzyme catalyzes Because both have been proposed be required mediating number crucial insulin responses, formation active signaling complex containing PKB, attractive ensuring all critical sites on targets such glycogen synthase kinase-3 are phosphorylated.