Methylation been found on a variety of lysine residues in varied histones: K4 (utilizing the one-letter amino-acid code for lysine), K9, K27, K36 and K79 in histone H3, K20 in histone H4, K59 in the globular domain of histone H4 2 and K26 of histone H1B three A number of proteins chargeable for the methylation of specific residues have been characterised, and all however certainly one of these incorporates a SET domain