Human glioma PKC-iota and PKC-betaII phosphorylate cyclin-dependent kinase activating kinase during the cell cycle

Cell Prolif. 2002 Feb;35(1):23-36. doi: 10.1046/j.1365-2184.2002.00220.x.


Cell cycle phase transition is regulated in part by the trimeric enzyme, cyclin-dependent kinase activating kinase (CAK) which phosphorylates and activates cyclin-dependent kinases (cdks). Protein kinase C (PKC) inhibitors prevent cell cycle phase transition, suggesting a fundamental role for PKCs in cell cycle regulation. We report that in glioma cells, CAK (cdk7) is constitutively associated with PKC-iota. In vitro phosphorylation, co-immunoprecipitation, and analysis of phosphorylated proteins by autoradiography indicate that CAK (cdk7) is a substrate for PKC-iota and PKC-betaII hyperphosphorylation. These results establish a role for PKC-iota and PKC-betaII in the activation of CAK during the glioma cell cycle.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Cell Cycle / physiology*
  • Cyclin-Dependent Kinase-Activating Kinase
  • Cyclin-Dependent Kinases / physiology
  • Glioma / pathology*
  • Glioma / physiopathology
  • Humans
  • Isoenzymes / antagonists & inhibitors
  • Isoenzymes / physiology*
  • Naphthalenes / pharmacology
  • Phosphorylation
  • Protein Kinase C / antagonists & inhibitors
  • Protein Kinase C / physiology*
  • Protein Kinase C beta
  • Protein Serine-Threonine Kinases / physiology*
  • Signal Transduction / physiology
  • Tumor Cells, Cultured


  • Isoenzymes
  • Naphthalenes
  • calphostin complex
  • Protein Serine-Threonine Kinases
  • Protein Kinase C
  • Protein Kinase C beta
  • protein kinase C lambda
  • Cyclin-Dependent Kinases
  • Cyclin-Dependent Kinase-Activating Kinase
  • CDK7 protein, human