SUMMARY PARAGRAPH for CDC20
CDC20 is an activator of the anaphase-promoting complex (APC), an E3 ubiquitin ligase in the ubiquitin-mediated proteolysis pathway (3). The APC ubiquitin ligase helps regulate the metaphase/anaphase transition and exit from mitosis/G1 entry through ubiquitination of various substrates. These include mitotic cyclins, the sister chromatid separation inhibitor Pds1p, the Kip1p and Cin8p motor proteins, Cdc5p, and the spindle disassembly factor, Ase1p (5, 6, 7, 8, 9, 10).
cdc20-1 mutants arrest in metaphase before the activation of APC-dependent proteolysis (11). Analysis of the mutants demonstrated that Cdc20p regulates the activity and substrate specificity of the APC (12). It serves as an activator of the APC and mediates ubiquitin-dependent protein degradation of Pds1p (7, 12), and the cyclins Clb5p and Clb3p (13) at the metaphase-to-anaphase transition of the cell cycle.
The timing of the association of Cdc20p with the APC is regulated. The levels of Cdc20p rise as cells enter mitosis and fall as cells exit mitosis, with the result that Cdc20 is bound to the APC only during M phase (and possibly during late G2) (14).
CDH1, another APC activator, is a homolog of CDC20 (12). CDC20 orthologs have also been identified in various species including worms, flies and humans (15, 3 , 12).
Last updated: 2005-05-11