A multiprotein complex that binds sister chromatids together during the initial stages of nuclear division in cells. It includes members of the SMC (structural maintenance of chromosomes) family of proteins. Cohesin complexes form a series of rings around the chromatids. At the onset of anaphase, when the sister chromatids have already attached to the spindle fibres, formation of the anaphase-promoting complex (APC) causes activation of the enzyme separase, which cuts the cohesin rings and abolishs the cohesion between the sister chromatids. This enables them to separate and move to opposite poles of the cell.
Subjects: Genetics and Genomics.