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Journal article

Identification of a PKB/Akt hydrophobic motif Ser-473 kinase as DNA-dependent protein kinase.

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  • 2004-07-21
Published in:
  • The Journal of biological chemistry. - 2004
3T3-L1 Cells
Amino Acid Motifs
Animals
Cell Line
Cell Line, Tumor
Cell Membrane
Chromatography, Gel
DNA, Complementary
DNA-Activated Protein Kinase
DNA-Binding Proteins
Enzyme Activation
Genetic Complementation Test
Glioblastoma
Humans
Insulin
Mice
Microscopy, Fluorescence
Models, Biological
Nuclear Proteins
Phosphorylation
Plasmids
Precipitin Tests
Protein-Serine-Threonine Kinases
Proto-Oncogene Proteins
Proto-Oncogene Proteins c-akt
Recombinant Proteins
Serine
Time Factors
Transfection
Vanadates
English Full activation of protein kinase B (PKB)/Akt requires phosphorylation on Thr-308 and Ser-473 by 3-phosphoinositide-dependent kinase-1 (PDK1) and Ser-473 kinase (S473K), respectively. Although PDK1 has been well characterized, the identification of the S473K remains controversial. A major PKB Ser-473 kinase activity was purified from the membrane fraction of HEK293 cells and found to be DNA-dependent protein kinase (DNA-PK). DNA-PK co-localized and associated with PKB at the plasma membrane. In vitro, DNA-PK phosphorylated PKB on Ser-473, resulting in a approximately 10-fold enhancement of PKB activity. Knockdown of DNA-PK by small interfering RNA inhibited Ser-473 phosphorylation induced by insulin and pervanadate. DNA-PK-deficient glioblastoma cells did not respond to insulin at the level of Ser-473 phosphorylation; this effect was restored by complementation with the human PRKDC gene. We conclude that DNA-PK is a long sought after kinase responsible for the Ser-473 phosphorylation step in the activation of PKB.
Language
  • English
Open access status
bronze
Identifiers
Persistent URL
https://folia.unifr.ch/global/documents/137386
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