Activator protein that regulates the ubiquitin ligase activity and substrate specificity of the anaphase promoting complex/cyclosome (APC/C). Required for the ubiquitination and subsequent degradation of the B-type cyclin CLB1 by the APC/C complex during meiosis. Required for meiosis I, late meiotic gene expression and spore wall assembly. Interacts with CDC16. Expressed and spliced only during meiosis dependent on the splicing factor MER1. The C-box is required for the association with the APC/C complex. Belongs to the WD repeat CDC20/Fizzy family.