These tails are topic to several submit-translational covalent modifications, including acetylation, phosphorylation, ubiquitination, sumoylation and methylation (reviewed in 1 ). Methylation been discovered on a range of lysine residues in various histones: K4 (using the only-letter amino-acid code for lysine), K9, K27, K36 and K79 in histone H3, K20 in histone H4, K59 within the globular area of histone H4 2 and K26 of histone H1B 3 Several proteins accountable for the methylation of particular residues have been characterised, and all but certainly one of these contains a SET domain