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. The CENPA-NAC complex recruits the CENPA-CAD (nucleosome distal) complex and may be involved in incorporation of newly synthesized CENPA into centromeres. Plays an important role in the correct PLK1 localization to the mitotic kinetochores. A scaffold protein responsible for the initial recruitment and maintenance of the kinetochore PLK1 population until its degradation. Involved in transcriptional repression. {ECO:0000269|PubMed:12941884, ECO:0000269|PubMed:16716197, ECO:0000269|PubMed:17081991}. This is the function of CENPU (centromere protein U, Ensembl gene identifier ENSG00000151725).