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 constitutive centromere-associated network (CCAN), which serves as a structural platform for outer kinetochore assembly (PubMed:22561346). CNN1 is important for the recruitment of the outer kinetochore Ndc80 complex (PubMed:23334295). Component of the inner kinetochore 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:14633972, PubMed:22561346). Interacts with outer kinetochore MIND complex subunit NNF1 (PubMed:14633972). Interacts with outer kinetochore Ndc80 complex subunits SPC24 and SPC25 (PubMed:22561346, PubMed:23334295). Phosphorylation of the C-ter by MPS1 kinase regulates interaction with the outer kinetochore Ndc80 complex. Present with 1300 molecules/cell in log phase SD medium. Belongs to the CENP-T/CNN1 family.