Which histone variant replaces H3 at the centromere?
Centromere identity epigenetically marked by incorporation of histone H3 variant CENP-A instead of canonical H3, producing specialized nucleosomes that survive throughout cell cycle and are replenished after replication. CENP-A contains centromere targeting domain CATD within histone fold, divergent N-terminus replaced, deposited specifically by HJURP chaperone complex at centromeres during early G1. H3.3 variant replaces H3 at actively transcribed genes and regulatory elements, H2A.Z at promoter flanks, H2A.X marks DNA double strand break sites. CENP-A depletion causes centromere inactivation, chromosome loss and aneuploidy. Therefore CENP-A represents H3 variant defining centromere.
Ref: Palmer et al., 1991 and Black et al., 2007; Lodish et al., Chapter 8: CENP-A Variant Replaces H3 at Centromere