Component of cohesin complex, a complex required for the cohesion of sister chromatids after DNA replication. The cohesin complex apparently forms a large proteinaceous ring within which sister chromatids can be trapped. At anaphase, the MCD1/SCC1 subunit of the complex is cleaved and dissociates from chromatin, allowing sister chromatids to segregate. The cohesin complex may also play a role in spindle pole assembly during mitosis. Interacts directly with MCD1 in cohesin complex. Cohesin complexes are composed of the SMC1 and SMC3 heterodimer attached via their hinge domain, MCD1 which link them, and IRR1/SCC3, which interacts with MCD1. The cohesin complex also interacts with SCC2, which is required for its association with chromosomes. Interacts with LIN1. Associates with chromatin. Before prophase it is scattered along chromosome arms. During prophase, most of cohesin complexes dissociate from chromatin except at centromeres, where cohesin complexes remain. At anaphase, the MCD1 subunit of the cohesin complex is cleaved, leading to the dissociation of the complex from chromosomes, allowing chromosome separation. Acetylated by ECO1. Present with 4090 molecules/cell in log phase SD medium. Belongs to the SCC3 family.