Sgo1 is a 561 amino acid nuclear and cytoplasmic protein that is widely expressed with highest expression in testis. Sgo1 localizes to the inner centromere throughout prophase until metaphase. Sgo1 is suggested to prevent premature dissociation of the cohesin complex from centromeres after prophase by impeding phosphorylation of the SA-2 subunit of the cohesin complex at the centromere. This ensures cohesin persistence at the centromere until cohesin cleavage is achieved by Separase at the anaphase stage of mitosis. Sgo1 is essential for proper chromosome segregation and for proper attachment of spindle microtubule to the kinetochore. Sgo1 may also play a role in the tension sensing mechanism of the spindle-assembly checkpoint by regulating Plk kinetochore affinity. Sgo1 exists as seven alternatively isoforms one of which (isoform 3) does not does not localize to kinetochores during any stages of the cell cycle