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Cdc20 is an essential cell-cycle regulator required for the completion of
mitosis in organisms from yeast to man and contains at its C terminus a WD40
repeat domain that mediates protein-protein interactions. In mitosis, Cdc20
binds to and activates the ubiquitin ligase activity of a large molecular
machine called the anaphase-promoting complex/cyclosome (APC/C) and enables the
ubiquitination and degradation of securin and cyclin B, thus promoting the onset
of anaphase and mitotic exit. APC/C(Cdc20) is temporally and spatially regulated
during the somatic and embryonic cell cycle by numerous mechanisms, including
the spindle checkpoint and the cytostatic factor (CSF). Therefore, Cdc20 serves
as an integrator of multiple intracellular signaling cascades that regulate
progression through mitosis. This review summarizes recent progress toward the
understanding of the functions of Cdc20, the mechanisms by which it activates
APC/C, and its regulation by phosphorylation and by association with its binding
proteins.
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