Required for full ubiquitin ligase activity of the anaphase promoting complex/cyclosome (APC/C) and may confer substrate specificity upon the complex. Is regulated by MAD2L1: in metaphase the MAD2L1-CDC20-APC/C ternary complex is inactive and in anaphase the CDC20-APC/C binary complex is active in degrading substrates. The CDC20-APC/C complex positively regulates the formation of synaptic vesicle clustering at active zone to the presynaptic membrane in postmitotic neurons. CDC20-APC/C-induced degradation of NEUROD2 induces presynaptic differentiation (By similarity). Interacts with NEK2 (By similarity). Protein modification; protein ubiquitination. Component of a complex with CDC20, CDC27, SPATC1 and TUBG1 (By similarity). Interacts with NEUROD2 (By similarity). Interacts with dimeric MAD2L1 in its closed conformation form (By similarity). Interacts with BUB1B (By similarity). The phosphorylated form interacts with APC/C (By similarity). Interacts with NINL (By similarity). May interact with MAD2L2 (By similarity). Interacts with CDK5RAP2 (By similarity). Interacts with SIRT2 (By similarity). Interacts with isoform 1 of NEK2 (By similarity). Interacts with HSF1 (via phosphorylated form); this interaction occurs in mitosis in a MAD2L1-dependent manner and prevents PLK1-stimulated degradation of HSF1 by blocking the recruitment of the SCF(BTRC) ubiquitin ligase complex (By similarity). Interacts (via the N-terminal substrate-binding domain) with FBXO5 (By similarity). Interacts with CCNF (By similarity). Phosphorylated during mitosis, probably by maturation promoting factor (MPF). Phosphorylated by BUB1 at Ser-41; Ser-72; Ser-92; Ser-153; Thr-157 and Ser-161. Phosphorylated by NEK2 (By similarity). Dephosphorylated by CTDP1. Acetylated. Deacetylated at Lys-66 by SIRT2; deacetylation enhances the interaction of CDC20 with CDC27, leading to activation of anaphase promoting complex/cyclosome (APC/C) (By similarity). Ubiquitinated and degraded by the proteasome during spindle assembly checkpoint. Ubiquitinated at Lys-490 during prometaphase. Ubiquitination at Lys-485 and Lys-490 has no effect on its ability to bind the APC/C complex (By similarity). Belongs to the WD repeat CDC20/Fizzy family.