Degradation of mitotic cyclins on exit from M phase occurs by ubiquitin-mediated proteolysis. The ubiquitination of mitotic cyclins is regulated by the @entity7319 ( @entity7319 ) or cyclosome. @entity70423 , the @entity1238 homolog of the Suc1/Cks protein, is required for some step in mitotic cyclin destruction in @entity1238 egg extracts. Specifically, if p9 is removed from interphase egg extracts, these p9-depleted extracts are unable to carry out the proteolysis of cyclin B after entry into mitosis and thus remain arrested in M phase. To explore the molecular basis of this defect, we depleted p9 from extracts that had already entered M phase and thus contained an active @entity7319 . We found that ubiquitin-mediated proteolysis of cyclin B was not compromised under these circumstances, suggesting that p9 is not directly required for ubiquitination or proteolysis. Further analysis of extracts from which p9 had been removed during interphase showed that, at the beginning of mitosis, these extracts are unable to carry out the hyperphosphorylation of the @entity42406 component of the @entity7319 , which coincides with the initial activation of the @entity7319 . p9 can be found in a complex with a small fraction of the @entity42406 protein during M phase but not interphase. The phosphorylation of the @entity42406 protein (either associated with the @entity7319 or in an isolated, bacterially expressed form) by recombinant @entity2111 /cyclin B is strongly enhanced by p9. Our results indicate that p9 directly regulates the phosphorylation of the @entity7319 by @entity2111 /cyclin B. These studies indicate that the Suc1/Cks protein modulates substrate recognition by a cyclin-dependent kinase.

@entity70423 , a @entity1238 Suc1/Cks protein, is essential for the XXXX -dependent phosphorylation of the anaphase- promoting complex at mitosis.

@entity1238 :: ('8355', 'Species') :: ['Xenopus'] @entity2111 :: ('379785(Tax:8355)', 'Gene') :: ['Cdc2'] @entity7319 :: ('MESH:D030401', 'Disease') :: ['APC', 'anaphase-promoting complex'] @entity42406 :: ('443994(Tax:8355)', 'Gene') :: ['Cdc27'] @entity70423 :: ('398059(Tax:8355)', 'Gene') :: ['Xe-p9']
@entity2111 :: (379785(Tax:8355),Gene) :: ['Cdc2']
