Figure 1.

Posttranslational modifications on histones. Four core histones H3, H4, H2A and H2B adopt a similar secondary structural fold called the histone fold domain or core domain of histones (circle). Moreover, the N-termini and C-termini of these core histones are called histone tails. Amino acid residues, represented by one letter, at the N-terminal tails of each core histones as well as posttranslational modifications including phosphorylation (blue oval) acetylation (green diamond), methylation (red circle) and ubiquitination (yellow cross) are shown.