An essential amino acid, l-lysine or lysine is important for human health. The exception to the rule is the DOT1 household, law firms members of which methylate K79 within the globular area of histone H3 and lawyers in my area that are structurally not related to SET-area proteins 4 - 6 Current work means that SET-area-containing proteins methylate a number of proteins in addition to histones (see later)