Cdc27 shares strong similarity with Saccharomyces cerevisiae protein Cdc27, and the gene product of Schizosaccharomyces pombe nuc 2. It is a component of the Anaphase Promoting Complex (APC), which is composed of eight protein subunits and is highly conserved in eucaryotic cells. The APC catalyzes the formation of the cyclin B ubiquitin conjugate that is responsible for the ubiquitin mediated proteolysis of B type cyclins. This protein and 3 other members of the APC complex contain the TPR (tetratricopeptide repeat), a protein domain important for protein protein interaction. This protein was shown to interact with mitotic checkpoint proteins including Mad2, p55CDC and BUBR1, and thus may be involved in controlling the timing of mitosis.