Component of the kinetochore, a multiprotein complex that assembles on centromeric DNA and attaches chromosomes to spindle microtubules, mediating chromosome segregation and sister chromatid segregation during meiosis and mitosis. Component of the inner kinetochore COMA complex, which connects centromere-associated proteins and the outer kinetochore. COMA interacts with other inner kinetochore proteins to form the inner kinetochore constitutive centromere-associated network (CCAN), which serves as a structural platform for outer kinetochore assembly. Component of the heterotetrameric kinetochore subcomplex COMA, which consists of AME1, CTF19, MCM21 and OKP1 (PubMed:14633972). The COMA subcomplex is part of a larger constitutive centromere-associated network (CCAN) (also known as central kinetochore CTF19 complex in yeast), which is composed of at least AME1, CHL4, CNN1, CTF3, CTF19, IML3, MCM16, MCM21, MCM22, MHF1, MHF2, MIF2, NKP1, NKP2, OKP1 and WIP1 (PubMed:12408861, PubMed:22561346). COMA binds the centromeric nucleosome-binding protein MIF2, and to the outer kinetochore MIND subcomplex, probably via AME1. AME1 interacts directly with OKP1 and an NKP1-NKP2 dimer (By similarity). Present with 1630 molecules/cell in log phase SD medium. Belongs to the CENP-U/AME1 family.