Part of the MIS12 complex which is required for normal chromosome alignment and segregation and for kinetochore formation during mitosis (PubMed:12515822, PubMed:15502821, PubMed:16585270). Essential for proper kinetochore microtubule attachments (PubMed:23891108). {ECO:0000269|PubMed:12515822, ECO:0000269|PubMed:15502821, ECO:0000269|PubMed:16585270, ECO:0000269|PubMed:23891108}. This is the function of MIS12 (MIS12 kinetochore complex component, Ensembl gene identifier ENSG00000167842).