Constitutive component of kinetochores that is essential for proper cell division during mitotic cell cycle (Probable). May play a role in the modulation of centromere during meiosis (PubMed:21695238). Localizes at centromeric regions throughout the mitotic cell cycle. Co-localizes with CENH3 during the cell cycle, from interphase to anaphase (PubMed:16331414). Localized at centromeres in meiotic cells (PubMed:21695238). Embryonic lethality when homozygous. Belongs to the mis12 family.