Component of the anaphase promoting complex/cyclosome (APC/C), a cell cycle-regulated E3 ubiquitin-protein ligase complex that controls progression through mitosis and the G1 phase of the cell cycle. Protein modification; protein ubiquitination. The APC/C is composed of at least 11 subunits that stay tightly associated throughout the cell cycle (By similarity). Binds to GIG1 and PYM. Part of the mitotic checkpoint complex (MCC); interacts with MAD2 and BUB1. Belongs to the WD repeat CDC20/Fizzy family.