Interaction between cyclin T1 and SCF(SKP2) targets CDK9 for ubiquitination and degradation by the proteasome.

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. SCF(SKP2) was recruited to CDK9/cyclin T1 via cyclin T1 in ...
an interaction requiring its PEST domain. CDK9 ubiquitination was modulated by cyclin T1 and p45(SKP2). CDK9 accumulated in p45(SKP2-/-) 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 SCF(SKP2) is mediated by cyclin T1 while ubiquitination occurs exclusively on CDK9.
Mesh Terms:
Animals, Cell Cycle, Cell Cycle Proteins, Cells, Cultured, Cyclin T, Cyclin-Dependent Kinase 9, Cyclin-Dependent Kinases, Cyclins, Cysteine Endopeptidases, Fibroblasts, Humans, Ligases, Mice, Multienzyme Complexes, Periodicity, Proteasome Endopeptidase Complex, Protein Binding, Protein Structure, Tertiary, Recombinant Fusion Proteins, S-Phase Kinase-Associated Proteins, Transcription, Genetic, Transfection, Ubiquitin-Protein Ligase Complexes, Ubiquitin-Protein Ligases, Ubiquitins
Mol. Cell. Biol.
Date: Dec. 01, 2001
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