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 13 subunits that stay tightly associated throughout the cell cycle: anapc1, anapc2, anapc3, anapc4, anapc5, anapc6, anapc7, anapc8, anapc10, anapc11, cdc20, cdc26 and cdh1. Belongs to the RING-box family.