Ubiquitination of the G1 cyclin Cln2p by a Cdc34p-dependent pathway.

摘要: Recombinant G1 cyclin Cln2p can bind to and stimulate the protein kinase activity of p34CDC28 (Cdc28p) in an extract derived from cyclin-depleted G1-arrested Saccharomyces cerevisiae cells. Upon activating Cdc28p, is extensively phosphorylated conjugated with multiubiquitin chains. Ubiquitination vitro requires Cdc34p ubiquitin-conjugating enzyme, phosphorylation unidentified factors yeast extract. by contributes instability vivo, as rate degradation reduced cdc34ts These results provide a molecular framework for suggest that multicomponent, regulated pathway specifies selective ubiquitination cyclins.