Component of the CENPA-NAC (nucleosome-associated) complex; a complex that plays a central role in assembly of kinetochore proteins; mitotic progression and chromosome segregation (By similarity). The CENPA-NAC complex recruits the CENPA-CAD (nucleosome distal) complex and may be involved in incorporation of newly synthesized CENPA into centromeres (By similarity). Part of a nucleosome-associated complex that binds specifically to histone H3-containing nucleosomes at the centromere; as opposed to nucleosomes containing CENPA. Component of the heterotetrameric CENP-T-W-S-X complex that binds and supercoils DNA; and plays an important role in kinetochore assembly. CENPW has a fundamental role in kinetochore assembly and function. It is one of the inner kinetochore proteins; with most further proteins binding downstream. Required for normal chromosome organization and normal progress through mitosis. {ECO:0000250; ECO:0000269|PubMed:19070575; ECO:0000269|PubMed:22304917}.