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Progression through mitosis is controlled by ubiquitin-mediated proteolysis of proteins by the anaphase-promoting complex/cyclosome (APC/C) in complex with its mitotic co-activator Cdc20. The APC/CCdc20 works in collaboration with two so-called E2 enzymes UbcH10 and Ube2S which carries activated ubiquitin molecules and assists in the covalent attachment of ubiquitin to a substrate. The APC/CCdc20 complex targets key substrates such as securin and cyclin B1 for degradation allowing sister chromatid separation and mitotic exit respectively. The APC/C belongs to the cullin-RING finger of E3 ligases and is composed of at least 15 subunits in humans with APC2 and APC11 constituting the cullin and RING finger subunits respectively. Despite its large size the APC/C is absolutely dependent on one of two co-activators, Cdc20 or Cdh1, for its activity. Cdc20 is the chief activator during mitosis while Cdh1 functions in the G1 phase of the cell cycle. The co-activators play a dual role in activating the APC/C firstly through direct binding to destruction motifs in substrates via their propeller domain and in collaboration with the APC10 subunit. Secondly the co-activators activate the APC/C by an unknown mechanism through an N-terminal C-box motif.


Cryo-EM structure of Cdc20 (purple) bound to the APC/C (yellow)





July 2016

Our PP2A-B56 motif paper

online in Molecular Cell

click here


July 2016

Our two pool BubR1 paper now

online at Nature Communications

click here


March 2016

Our Cdc20 phosphorylation paper

is now online at

Nature Communications

click here