Histone H2A.Z variants affect nucleosome stability. (a) Amino acid sequence of mouse/carp H2A.Z.2.1 in comparison to carp H2A.Z.7 and mouse H2A.Z.2.2, which are preferentially expressed in the brain. The helical regions of the proteins are indicated. The alpha helical domain shown in red was determined in silico using prediction algorithms. The sites of acetylation (Ac) and ubiquitination (Ub) are also shown. (b) In contrast to H2A.Z.2.1 (orange), brain H2A.Z.2.2 (green) has been shown to destabilize the nucleosome and it is possible that H2A.Z.7 (red) has similar destabilizing properties. The colors for the canonical histones are: H2A, light salmon; H2B, yellow; H3, blue; H4, light green.