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. CENPN is the first protein to bind specifically to CENPA nucleosomes and the direct binding of CENPA nucleosomes by CENPN is required for centromere assembly. Required for chromosome congression and efficiently align the chromosomes on a metaphase plate. {ECO:0000269|PubMed:16622419; ECO:0000269|PubMed:16716197; ECO:0000269|PubMed:18007590; ECO:0000269|PubMed:19543270}.