Involved in chromosome cohesion during mitosis and meiosis by preventing premature dissociation of cohesin complex from centromeres after prophase, when most of cohesin complex dissociates from chromosomes arms. Required for faithful mitotic chromosome segregation and proper kinetochore orientation during meiosis I. In contrast to sgo1, it is dispensable for centromeric protection of rec8 during meiosis I as well as protection of rad21 during mitosis. Required to sense the lack of tension at centromeres during mitosis. Localizes to the centromere. Bub1 is required for centromeric localization (PubMed:14730319). At the onset of anaphase I, Sgo1 decreases markedly (PubMed:14730319). Present throughout the mitotic and meiotic cell cycle. 'Shugoshin' means 'guardian spirit' in Japanese. Belongs to the shugoshin family.