Regulation of kinase activity of 3-phosphoinositide-dependent protein kinase-1 by binding to 14-3-3.
3-Phosphoinositide-dependent protein kinase-1 (PDK1) plays a central role in activating the protein kinase A, G, and C subfamily. In particular, PDK1 plays an important role in regulating the Akt survival pathway by phosphorylating Akt on Thr-308. PDK1 kinase activity was thought to be constitutively active; however, recent reports suggested that its activity is regulated by binding to other proteins, such as protein kinase C-related kinase-2 (PRK2), p90 ribosomal protein S6 kinase-2 (RSK2), and heat-shock protein 90 (Hsp90). Here we report that PDK1 binds to 14-3-3 proteins in vivo and in vitro through the sequence surrounding Ser-241, a residue that is phosphorylated by itself and is critical for its kinase activity. Mutation of PDK1 to increase its binding to 14-3-3 decreased its kinase activity in vivo. By contrast, mutation of PDK1 to decrease its interaction with 14-3-3 resulted in increased PDK1 kinase activity. Moreover, incubation of wild-type PDK1 with recombinant 14-3-3 in vitro decreased its kinase activity. These data indicate that PDK1 kinase activity is negatively regulated by binding to 14-3-3 through the PDK1 autophosphorylation site Ser-241.
Pubmed ID: 12177059 RIS Download
14-3-3 Proteins | 3-Phosphoinositide-Dependent Protein Kinases | 3T3 Cells | Animals | Binding Sites | Blotting, Western | COS Cells | Catalysis | Cell Line | DNA, Complementary | Down-Regulation | Gene Expression Regulation, Enzymologic | Genetic Vectors | Glutathione Transferase | HSP90 Heat-Shock Proteins | Humans | Mice | Mutagenesis, Site-Directed | Mutation | Peptides | Plasmids | Precipitin Tests | Protein Binding | Protein Isoforms | Protein Kinase C | Protein-Serine-Threonine Kinases | Recombinant Fusion Proteins | Recombinant Proteins | Ribosomal Protein S6 Kinases, 90-kDa | Serine | Signal Transduction | Transfection | Tumor Cells, Cultured | Tyrosine 3-Monooxygenase