Abstract

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.

Keywords

Protein kinase BMAP2K7Mitogen-activated protein kinase kinasePhosphorylationProtein kinase AMolecular biologyCyclin-dependent kinase 2AKT1Cyclin-dependent kinase 9ChemistryKinaseBiologyCell biologyBiochemistry

MeSH Terms

3T3-L1 CellsAmino Acid MotifsAnimalsCell LineCell LineTumorCell MembraneChromatographyGelDNAComplementaryDNA-Activated Protein KinaseDNA-Binding ProteinsEnzyme ActivationGenetic Complementation TestGlioblastomaHumansInsulinMiceMicroscopyFluorescenceModelsBiologicalNuclear ProteinsPhosphorylationPlasmidsPrecipitin TestsProtein Serine-Threonine KinasesProto-Oncogene ProteinsProto-Oncogene Proteins c-aktRecombinant ProteinsSerineTime FactorsTransfectionVanadates

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Publication Info

Year
2004
Type
article
Volume
279
Issue
39
Pages
41189-41196
Citations
485
Access
Closed

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Cite This

Jianhua Feng, Jongsun Park, Peter Cron et al. (2004). Identification of a PKB/Akt Hydrophobic Motif Ser-473 Kinase as DNA-dependent Protein Kinase. Journal of Biological Chemistry , 279 (39) , 41189-41196. https://doi.org/10.1074/jbc.m406731200

Identifiers

DOI
10.1074/jbc.m406731200
PMID
15262962

Data Quality

Data completeness: 86%