Composed of more than ten subunits, the anaphase-promoting complex (APC) acts in a cell-cycle dependent manner to promote the separation of sister chromatids during the transition between metaphase and anaphase in mitosis. APC, or cyclosome, accomplishes this progression through the ubiquitination of mitotic cyclins and other regulatory proteins that are targeted for destruction during cell division. APC is phosphorylated, and thus activated, by protein kinases Cdk1/cyclin B and polo-like kinase (Plk). APC is under tight control by a number of regulatory factors, including CDC20, CDH1 and MAD2. Specifically, CDC20 and CDH1 directly bind to and activate the cyclin-ubiquitination activity of APCs. In contrast, MAD2 inhibits APC by forming a ternary complex with CDC20 and APC, thus preventing APC activation. APC10 contains a Doc1 homology domain, which is a beta-sandwich structure common to many other putative E3 ubiquitin ligases. APC10 binds to core APC subunits throughout the cell cycle. Specifically, APC10 binds to the C-terminus of CDC27/APC3. During mitosis, APC10 is localized in centrosomes and mitotic spindles. APC10 also localizes to kinetochores from prophase to anaphase, and to the midbody in telophase and cytokinesis.