This gene encodes a tetratricopeptide repeat-containing component of the anaphase promoting complex/cyclosome (APC/C), a large E3 ubiquitin ligase that controls cell cycle progression by targeting a number of cell cycle regulators such as B-type cyclins for 26S proteasome-mediated degradation through ubiquitination. The encoded protein is required for the proper ubiquitination function of APC/C and for the interaction of APC/C with transcription coactivators. It also interacts with polyA binding protein and represses internal ribosome entry site-mediated translation. Multiple transcript variants encoding different isoforms have been found for this gene. These differences cause translation initiation at a downstream AUG and result in a shorter protein (isoform b), compared to isoform a. [provided by RefSeq, Nov 2008].