Cyclin K functions as a CDK9 regulatory subunit and participates in RNA polymerase II transcription.
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Fu TJ, Peng J, Lee G, Price DH, Flores O
Cyclin K functions as a CDK9 regulatory subunit and participates in RNA polymerase II transcription.
J Biol Chem. 1999 Dec 3;274(49):34527-30.
- PubMed ID
- 10574912 [ View in PubMed]
- Abstract
Important progress in the understanding of elongation control by RNA polymerase II (RNAPII) has come from the recent identification of the positive transcription elongation factor b (P-TEFb) and the demonstration that this factor is a protein kinase that phosphorylates the carboxyl-terminal domain (CTD) of the RNAPII largest subunit. The P-TEFb complex isolated from mammalian cells contains a catalytic subunit (CDK9), a cyclin subunit (cyclin T1 or cyclin T2), and additional, yet unidentified, polypeptides of unknown function. To identify additional factors involved in P-TEFb function we performed a yeast two-hybrid screen using CDK9 as bait and found that cyclin K interacts with CDK9 in vivo. Biochemical analyses indicate that cyclin K functions as a regulatory subunit of CDK9. The CDK9-cyclin K complex phosphorylated the CTD of RNAPII and functionally substituted for P-TEFb comprised of CDK9 and cyclin T in in vitro transcription reactions.