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Cyclin K Functions as a CDK9 Regulatory Subunit and Participates in RNA Polymerase II Transcription
Journal article   Open access   Peer reviewed

Cyclin K Functions as a CDK9 Regulatory Subunit and Participates in RNA Polymerase II Transcription

Tsu-Ju Fu, Junmin Peng, Gary Lee, David H Price and Osvaldo Flores
The Journal of biological chemistry, Vol.274(49), pp.34527-34530
12/03/1999
DOI: 10.1074/jbc.274.49.34527
PMID: 10574912
url
https://doi.org/10.1074/jbc.274.49.34527View
Published (Version of record) Open Access

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.

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