ANAPC4 is a subunit of the anaphase promoting complex/cyclosome (APC/C), an E3 ubiquitin ligase whose activity is regulated through the cell cycle. The APC/C mediates ubiquitination and subsequent degradation of target proteins. It mainly forms 'Lys-11'-linked polyubiquitin chains and, to a lesser extent, 'Lys-48'- and 'Lys-63'-linked chains, and it catalyses assembly of branched 'Lys-11'/'Lys-48' ubiquitin chains on its substrates.

At the metaphase/anaphase transition the APC/C is activated by CDC20, which directs the degradation of cyclin B and securin. The complex is in turn regulated by the mitotic checkpoint complex (MCC), which inhibits the APC/C and delays chromosome segregation. Ubiquitinated substrates, including mitotic cyclins and anaphase inhibitors, are degraded by the 26S proteasome, which allows the cell to pass from metaphase into anaphase.

The human ANAPC4 gene encodes a nuclear protein that belongs to the APC4 family and is classed by HGNC in the anaphase promoting complex gene group. The vertebrate APC is described as containing eight subunits, and its composition is highly conserved from yeast to humans. NCBI notes that the exact function of this individual gene product is not known, and that two transcript variants encoding different isoforms have been reported. The mouse ortholog is Anapc4.