The cyclin-ubiquitin ligase activity of cyclosome/APC is jointly activated by protein kinases Cdk1-cyclin B and Plk.

摘要: The cyclosome/anaphase-promoting complex is a multisubunit ubiquitin ligase that targets for degradation mitotic cyclins and some other cell cycle regulators in exit from mitosis. It becomes enzymatically active at the end of activation cyclosome initiated by its phosphorylation, process necessary conversion to an form ancillary protein Cdc20/Fizzy. Previous reports have implicated either cyclin-dependent kinase 1-cyclin B or polo-like as major directly phosphorylates activates cyclosome. These conflicting results could be due use partially purified preparations immunoprecipitated cyclosome, whose interactions with kinases factors may hampered binding immobilized antibody. To examine this problem, we HeLa cells combination affinity chromatography ion exchange procedures. With preparations, found both phosphorylated but pattern phosphorylation different subunits two was not similar. Each restore only cyclin-ubiquitin activity dephosphorylated However, following kinases, additive nearly complete restoration observed. suggested joint complementary kinases.