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 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 RAD21 in cohesin complex. Cohesin complexes are composed of a heterodimer between a SMC1 protein (SMC1A or SMC1B) and SMC3, which are attached via their hinge domain, and RAD21 which link them at their heads, and one STAG protein (STAG1, STAG2 or STAG3). In cohesin complexes, STAG2 is mutually exclusive with STAG1 and STAG3. Associates with chromatin. Before prophase it is scattered along chromosome arms. During prophase, most of cohesin complexes dissociate from chromatin probably because of phosphorylation by PLK1, except at centromeres, where cohesin complexes remain. At anaphase, the RAD21 subunit of cohesin is cleaved, leading to the dissociation of the complex from chromosomes, allowing chromosome separation. In germ cells, cohesin complex dissociates from chromatin at prophase I, and may be replaced by a meiosis-specific cohesin complex. Phosphorylated by PLK1. The large dissociation of cohesin from chromosome arms during prophase is partly due to its phosphorylation (By similarity). The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. Belongs to the SCC3 family. Variants MKMS 743-TRP--PHE-1231 DEL and HPE13 1033-ARG--PHE-1231 DEL were previously described; however, the corresponding paper has been retracted as Case 1's sex was incorrectly reported invalidating the conclusions. Truncated N-terminus.