Figure 2.

The histone code. a Schematic illustration of the nucleosome. The histones are represented by a gray cylinder and the nucleosomal histone tails are shown as small beads irradiating out of the cylinder. The post-translational modifications of the lysine residues in the histone tails are shown by red and green circles. b Post-translational modifications of lysine residues in the tail of nucleosomal histone H3, associated with active transcription (green). Note the inclusion of trimethyl lysine K4 and the acetylation of several residues. c Repressive modifications of lysine residues in position 9 and 27