Abstract
Transcription factor IIH (TFIIH) contains a kinase capable of phosphorylating the carboxy-terminal domain (CTD) of the largest subunit of RNA polymerase II (RNAPII). Here we report the identification of the Cdk-activating kinase (Cak) complex (Cdk7 and cyclin H) as a component of TFIIH after extensive purification of TFIIH by chromatography. We find that affinity-purified antibodies directed against cyclin H inhibit TFIIH-dependent transcription and that both cyclin H and Cdk7 antibodies inhibit phosphorylation of the CTD of the largest subunit of the RNAPII in the preinitiation complex. Cak is present in at least two distinct complexes, TFIIH and a smaller complex that is unable to phosphorylate RNAPII in the preinitiation complex. Both Cak complexes, as well as recombinant Cak, phosphorylate a CTD peptide. Finally, TFIIH was shown to phosphorylate both Cdc2 and Cdk2, suggesting that there could be a link between transcription and the cell cycle machinery.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Amino Acid Sequence
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Chromatography, Affinity
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Cyclin H
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Cyclin-Dependent Kinase-Activating Kinase
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Cyclin-Dependent Kinases*
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Cyclins / metabolism
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Detergents
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HeLa Cells
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Humans
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Immunologic Techniques
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Molecular Sequence Data
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Phosphorylation
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Protein Kinases / metabolism
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Protein Serine-Threonine Kinases / isolation & purification
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Protein Serine-Threonine Kinases / metabolism*
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RNA Polymerase II / metabolism
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Recombinant Proteins / metabolism
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Sarcosine / analogs & derivatives
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Transcription Factor TFIIH
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Transcription Factors / chemistry
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Transcription Factors / metabolism*
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Transcription Factors, TFII*
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Transcription, Genetic
Substances
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CCNH protein, human
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Cyclin H
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Cyclins
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Detergents
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Recombinant Proteins
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Transcription Factors
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Transcription Factors, TFII
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Transcription Factor TFIIH
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sarkosyl
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Protein Kinases
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carboxy-terminal domain kinase
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Protein Serine-Threonine Kinases
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Cyclin-Dependent Kinases
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RNA Polymerase II
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Sarcosine
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Cyclin-Dependent Kinase-Activating Kinase
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CDK7 protein, human