The rat CENP-A protein. (a) Alignment of predicted CENP-A proteins of mammals. Relative to other mammalian CENP-As, rat CENP-A has a 25 amino-acid insertion that arises from a duplication of the amino terminus, shown as over-lined regions. The boundary between the tail and the histone-fold domains (HFD) is indicated below the alignment, along with the position of Loop 1. (b) Alignment of duplicated regions of the rat Cenpa gene (rat1 and rat2) with Cenpa genes of mouse and Chinese hamster. The region that became duplicated in rat extends from upstream of the start codon to codon 22 in mouse and hamster, and is bounded by a conserved dodecamer repeat. The encoded amino acids are shown above (rat1) or below (rat2) the duplicated sequence.