From: Histone variants: are they functionally heterogeneous?
Variant | Percentage of | Essential for | Proposed function |
---|---|---|---|
 | amino-acid | viability? |  |
 | identity to |  |  |
 | major isotype (%) |  |  |
CENP-A | 62 | Yes (mouse) | Kinetochore |
 |  |  | assembly |
MacroH2A | 64 (in histone | Not known | X-chromosome |
 | region) |  | inactivation; gene |
 |  |  | expression |
H2A-Bbd | 42 | Not known | Transcriptional |
 |  |  | activation |
H2A.Z | 59 | Yes | Unclear; altered higher- |
 |  | (mouse, flies, | order chromatin |
 |  | Tetrahymena) | structure |