CENP-U is one of the components that assembles onto the CENP-A-nucleosome associated complex (NAC). The centromere, which is the basic element of chromosome inheritance, is epigenetically determined in mammals. CENP-A, the centromere-specific histone H3 variant, assembles an array of nucleosomes and it is this that seems to be the prime candidate for specifying centromere identity. CENP-A nucleosomes directly recruit a proximal CENP-A nucleosome associated complex (NAC) comprised of CENP-M, CENP-N and CENP-T, CENP-U(50), CENP-C and CENP-H. Assembly of the CENP-A NAC at centromeres is dependent on CENP-M, CENP-N and CENP-T. Additionally, there are seven other subunits which make up the CENP-A-nucleosome distal (CAD) centromere, CENP-K, CENP-L, CENP-O, CENP-P, CENP-Q, CENP-R and CENP-S, also assembling on the CENP-A NAC [1]. FTA4 is the equivalent component of the fission yeast Sim4 complex.

1: The human CENP-A centromeric nucleosome-associated complex. Foltz DR, Jansen LE, Black BE, Bailey AO, Yates JR 3rd, Cleveland DW; Nat Cell Biol. 2006;8:458-469. PMID:16622419