title: Molecular mechanism for the regulation of protein kinase B/Akt by hydrophobic motif phosphorylation.
abstract: Protein kinase B/Akt plays crucial roles in promoting cell survival and mediating insulin responses. The enzyme is stimulated by phosphorylation at two regulatory sites: Thr 309 of the activation segment and Ser 474 of the hydrophobic motif, a conserved feature of many AGC kinases. Analysis of the crystal structures of the unphosphorylated and Thr 309 phosphorylated states of the PKB kinase domain provides a molecular explanation for regulation by Ser 474 phosphorylation. Activation by Ser 474 phosphorylation occurs via a disorder to order transition of the alphaC helix with concomitant restructuring of the activation segment and reconfiguration of the kinase bilobal structure. These conformational changes are mediated by a phosphorylation-promoted interaction of the hydrophobic motif with a channel on the N-terminal lobe induced by the ordered alphaC helix and are mimicked by peptides corresponding to the hydrophobic motif of PKB and potently by the hydrophobic motif of PRK2.
authors.affiliation: Section of Structural Biology, Institute of Cancer Research, Chester Beatty Laboratories, 237 Fulham Road, London SW3 6JB, UK.
authors.forename: Jing
authors.initials: J
authors.lastname: Yang
authors.forename: Peter
authors.initials: P
authors.lastname: Cron
authors.forename: Vivienne
authors.initials: V
authors.lastname: Thompson
authors.forename: Valerie M
authors.initials: VM
authors.lastname: Good
authors.forename: Daniel
authors.initials: D
authors.lastname: Hess
authors.forename: Brian A
authors.initials: BA
authors.lastname: Hemmings
authors.forename: David
authors.initials: D
authors.lastname: Barford
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D017868:Cyclic AMP-Dependent Protein Kinases / Q000737:chemistry / Q000235:genetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010455:Peptides / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases; D017434:Protein Structure, Tertiary; D011518:Proto-Oncogene Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D016415:Sequence Alignment
chemical_list: D010455:Peptides; D011518:Proto-Oncogene Proteins; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D017868:Cyclic AMP-Dependent Protein Kinases