Molecular mechanism for the regulation of protein kinase B/Akt by hydrophobic motif phosphorylation

Mol Cell. 2002 Jun;9(6):1227-40. doi: 10.1016/s1097-2765(02)00550-6.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs
  • Amino Acid Sequence
  • Binding Sites
  • Crystallography, X-Ray
  • Cyclic AMP-Dependent Protein Kinases / chemistry
  • Cyclic AMP-Dependent Protein Kinases / genetics
  • Models, Molecular
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Peptides / genetics
  • Peptides / metabolism
  • Phosphorylation
  • Protein Structure, Tertiary
  • Protein-Serine-Threonine Kinases*
  • Proto-Oncogene Proteins / chemistry
  • Proto-Oncogene Proteins / genetics
  • Proto-Oncogene Proteins / metabolism*
  • Proto-Oncogene Proteins c-akt
  • Sequence Alignment


  • Peptides
  • Proto-Oncogene Proteins
  • Protein-Serine-Threonine Kinases
  • Proto-Oncogene Proteins c-akt
  • Cyclic AMP-Dependent Protein Kinases

Associated data

  • PDB/1GZK
  • PDB/1GZN
  • PDB/1GZO