Component of the CENPA-HI complex, a centromeric complex involved in assembly of kinetochore proteins, mitotic progression and chromosome segregation (By similarity). Involved in kinetochore assembly and required for recovery from spindle damage. Component of the CENPA-HI complex, at least composed of CENPH, CENPI, CENPK, CENPL, CENPM, CENPO and CENPP. Component of a discrete complex composed of at least CENPO, CENPP, CENPQ, CENPR and CENPU. Localizes exclusively in the centromeres. Increases time to progress through G2/M phase. Belongs to the CENP-O/MCM21 family.