The metaphase-to-anaphase transition is the final discrete event in duplication and separation of the genetic material of the cell. Its timing is regulated by the activation of the anaphase-promoting complex (APC). In both budding and fission yeast, the degradation of the Pds1 or Cut2 protein, respectively, is required for the onset of sister chromatid separation. Both proteins are APC substrates. Pds1 and Cut2 proteins associate with the yeast separin proteins Esp1 and Cut1, respectively, and prevent the separins from promoting chromatid separation. Pds1 and Cut2 are also called anaphase inhibitors or securins