Abstract
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
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Cell Cycle / physiology*
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Cyclin-Dependent Kinase-Activating Kinase
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Cyclin-Dependent Kinases / physiology
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Glioma / pathology*
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Glioma / physiopathology
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Humans
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Isoenzymes / antagonists & inhibitors
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Isoenzymes / physiology*
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Naphthalenes / pharmacology
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Phosphorylation
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Protein Kinase C / antagonists & inhibitors
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Protein Kinase C / physiology*
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Protein Kinase C beta
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Protein Serine-Threonine Kinases / physiology*
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Signal Transduction / physiology
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Tumor Cells, Cultured
Substances
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Isoenzymes
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Naphthalenes
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calphostin complex
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Protein Serine-Threonine Kinases
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Protein Kinase C
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Protein Kinase C beta
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protein kinase C lambda
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Cyclin-Dependent Kinases
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Cyclin-Dependent Kinase-Activating Kinase
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CDK7 protein, human