On the base of the channel is the methyltransfer pore, which connects the pocket to the AdoMet-binding cleft. Methylation been discovered on a range of lysine residues in numerous histones: solicitor K4 (using the single-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 responsible for the methylation of particular residues have been characterized, and all but one of these comprises a SET domain