Interaction between Cyclin T1 and SCFSKP2 Targets CDK9 for Ubiquitination and Degradation by the Proteasome
Open Access
- 1 December 2001
- journal article
- Published by Taylor & Francis in Molecular and Cellular Biology
- Vol. 21 (23) , 7956-7970
- https://doi.org/10.1128/mcb.21.23.7956-7970.2001
Abstract
CDK9 paired with cyclin T1 forms the human P-TEFb complex and stimulates productive transcription through phosphorylation of the RNA polymerase II C-terminal domain. Here we report that CDK9 is ubiquitinated and degraded by the proteasome whereas cyclin T1 is stable. SCFSKP2 was recruited to CDK9/cyclin T1 via cyclin T1 in an interaction requiring its PEST domain. CDK9 ubiquitination was modulated by cyclin T1 and p45SKP2. CDK9 accumulated in p45SKP2−/− cells, and its expression during the cell cycle was periodic. The transcriptional activity of CDK9/cyclin T1 on the class II major histocompatibility complex promoter could be regulated by CDK9 degradation in vivo. We propose a novel mechanism whereby recruitment of SCFSKP2 is mediated by cyclin T1 while ubiquitination occurs exclusively on CDK9.Keywords
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