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Activation of cyclin E/CDK2 is coupled to site‐specific autophosphorylation and ubiquitin‐dependent degradation of cyclin E.
Author(s) -
Won K. A.,
Reed S. I.
Publication year - 1996
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1996.tb00793.x
Subject(s) - cyclin , autophosphorylation , biology , cyclin a , cyclin e , cyclin a2 , cyclin b1 , cyclin dependent kinase , microbiology and biotechnology , cell cycle , cyclin dependent kinase 1 , biochemistry , phosphorylation , protein kinase a , gene
A yeast screen was developed to identify mutations in human cyclin E that lead to stabilization of the protein in order to identify determinants important for cyclin E turnover. Both C‐terminal truncations and missense mutations near the C‐terminus of cyclin E conferred hyperstability in vivo, suggesting that sequences in this region were critical for turnover. The following observations indicate that autophosphorylation of CDK2/cyclin E on Thr380 of the cyclin regulates cyclin E destruction: (i) mutation of Thr380 to Ala stabilizes cyclin E in yeast and mammalian cells; (ii) cyclin E/CDK2 autophosphorylates on cyclin E in vitro and cyclin E is a phosphoprotein in vivo in mammalian cells; (iii) the T380A mutation eliminates phosphorylation on the same site in mammalian cells and in vitro; (iv) inhibiting CDK2 activity in vivo stabilizes cyclin E; (v) the T380A mutation prevents ubiquitination of cyclin E. These results suggest a model where activation of cyclinE/CDK2 is coupled to cyclin E turnover via site‐specific phosphorylation, which acts as a signal for ubiquitination and proteasome processing.