The centromere protein B (CENP-B) dimerisation domain is composed of two alpha-helices, which are folded into an antiparallel configuration. Dimerisation of CENP-B is mediated by this domain, in which monomers dimerise to form a symmetrical, antiparallel, four-helix bundle structure with a large hydrophobic patch in which 23 residues of one monomer form van der Waals contacts with the other monomer. This CENP-B dimer configuration may be suitable for capturing two distant CENP-B boxes during centromeric heterochromatin formation [1].

1: Crystal structure of the human centromere protein B (CENP-B) dimerization domain at 1.65-A resolution. Tawaramoto MS, Park SY, Tanaka Y, Nureki O, Kurumizaka H, Yokoyama S; J Biol Chem. 2003;278:51454-51461. PMID:14522975