Fig. 2. The cohesin complex and its dissociation by separase. A proposed model for the cohesin complex and its dissociation by separase. In mitosis, the onset of anaphase is triggered by the separase-dependent cleavage of Rad21/Scc1, a cohesin subunit that might bind the two ends of Smc1-Smc3 heterodimer and thereby hold sister chromatids. During meiosis, Rad21/Scc1 is largely replaced by Rec8 and Psc3 is partly replaced by Rec11.