These tails are topic to several submit-translational covalent modifications, together with acetylation, phosphorylation, ubiquitination, sumoylation and methylation (reviewed in 1 ). Methylation been discovered on a variety of lysine residues in varied histones: K4 (using the single-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 three Several proteins responsible for the methylation of specific residues have been characterized, and all but certainly one of these accommodates a SET domain