Cdk-activating kinase complex is a component of human transcription factor TFIIH.
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.
Shiekhattar
R
R
Howard Hughes Medical Institute, Department of Biochemistry, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, Piscataway 08854-5635.
Mermelstein
F
F
Fisher
R P
RP
Drapkin
R
R
Dynlacht
B
B
Wessling
H C
HC
Morgan
D O
DO
Reinberg
D
D
D000595:Amino Acid Sequence; D002846:Chromatography, Affinity; D056748:Cyclin H; D018844:Cyclin-Dependent Kinases; D016213:Cyclins / Q000378:metabolism; D003902:Detergents; D006367:HeLa Cells; D006801:Humans; D007158:Immunologic Techniques; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000302:isolation & purification / Q000378:metabolism*; D012319:RNA Polymerase II / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D012521:Sarcosine / Q000031:analogs & derivatives; D051758:Transcription Factor TFIIH; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*; D019473:Transcription Factors, TFII; D014158:Transcription, Genetic; D000095043:Cyclin-Dependent Kinase-Activating Kinase
C534751:CCNH protein, human; D056748:Cyclin H; D016213:Cyclins; D003902:Detergents; D011994:Recombinant Proteins; D014157:Transcription Factors; D019473:Transcription Factors, TFII; D051758:Transcription Factor TFIIH; C025231:sarkosyl; D011494:Protein Kinases; C060137:carboxy-terminal domain kinase; D017346:Protein Serine-Threonine Kinases; D018844:Cyclin-Dependent Kinases; D012319:RNA Polymerase II; D012521:Sarcosine; D000095043:Cyclin-Dependent Kinase-Activating Kinase; C000722416:CDK7 protein, human