These tails are topic to a number of post-translational covalent modifications, including acetylation, law firm phosphorylation, ubiquitination, sumoylation and methylation (reviewed in 1 ). Methylation been found on a variety of lysine residues in numerous 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 domain of histone H4 2 and K26 of histone H1B 3 Several proteins responsible for the methylation of specific residues have been characterized, and all however one in every of these accommodates a SET area