Recombinant Xenopus laevis Cyclin-dependent kinase 7 (cdk7)

Serine/threonine kinase involved in cell cycle control and in RNA polymerase II-mediated RNA transcription. Cyclin-dependent kinases (CDKs) are activated by the binding to a cyclin and mediate the progression through the cell cycle. Each different complex controls a specific transition between 2 subsequent phases in the cell cycle. Required for both activation and complex formation of cdk1/cyclin-B during G2-M transition, and for activation of cdk2/cyclins during G1-S transition (but not complex formation). cdk7 is the catalytic subunit of the CDK-activating kinase (CAK) complex. CAK activates the cyclin-associated kinases cdk1, cdk2, cdk4 and cdk6 by threonine phosphorylation, thus regulating cell cycle progression. CAK complexed to the core-TFIIH basal transcription factor activates RNA polymerase II by serine phosphorylation of the repetitive C-terminal domain (CTD) of its large subunit (polr2a), allowing its escape from the promoter and elongation of the transcripts. Involved in negative regulation of the meiotic maturation of Xenopus oocytes.