Integrin-linked kinase regulates phosphorylation of serine 473 of protein kinase B by an indirect mechanism

Oncogene. 1999 Dec 23;18(56):8024-32. doi: 10.1038/sj.onc.1203258.

Abstract

The serine threonine kinase protein kinase B regulates cellular activities as diverse as glycogen metabolism and apoptosis. Full activation of protein kinase B requires 3-phosphoinositides and dual phosphorylation on threonine-308 and serine-473. CaM-K kinase and 3-phosphoinositide dependent-kinase-1 phosphorylate threonine-308. Integrin-linked kinase reportedly phophorylates serine-473. Consistent with this, in a model COS cell system we show that expression of wild-type integrin-linked kinase promotes the wortmannin sensitive phosphorylation of serine-473 of protein kinase B and its downstream substrates, and inhibits C2-ceramide induced apoptosis. In contrast, integrin-linked kinase mutated in a lysine residue critical for function in protein kinases is inactive in these experiments, and furthermore, acts dominantly to block serine-473 phosphorylation induced by ErbB4. However, alignment of analogous sequences from different species demonstrates that integrin-linked kinase is not a typical protein kinase and identifies a conserved serine residue which potentially regulates kinase activity in a phosphorylation dependent manner. Mutation of this serine to aspartate or glutamate, but not alanine, in combination with the inactivating lysine mutation restores integrin-linked kinase dependent phosphorylation of serine-473 of protein kinase B. These data strongly suggest that integrin-linked kinase does not possess serine-473 kinase activity but functions as an adaptor to recruit a serine-473 kinase or phosphatase.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • COS Cells
  • Caenorhabditis elegans
  • Caenorhabditis elegans Proteins
  • Catalytic Domain
  • Drosophila Proteins
  • Drosophila melanogaster
  • Humans
  • Molecular Sequence Data
  • Phosphatidylinositols / metabolism
  • Phosphorylation
  • Phosphoserine / metabolism
  • Protein-Serine-Threonine Kinases / chemistry*
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism*
  • Proto-Oncogene Proteins / chemistry
  • Proto-Oncogene Proteins / metabolism*
  • Proto-Oncogene Proteins c-akt
  • Proto-Oncogene Proteins c-raf / chemistry
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / metabolism
  • Sequence Alignment
  • Sequence Homology, Amino Acid
  • Transfection

Substances

  • Caenorhabditis elegans Proteins
  • Drosophila Proteins
  • Phosphatidylinositols
  • Proto-Oncogene Proteins
  • Recombinant Proteins
  • Phosphoserine
  • integrin-linked kinase
  • Akt1 protein, Drosophila
  • Protein-Serine-Threonine Kinases
  • Proto-Oncogene Proteins c-akt
  • Proto-Oncogene Proteins c-raf
  • akt-1 protein, C elegans

Associated data

  • GENBANK/AJ249344
  • GENBANK/AJ249345