Diverse signal transduction pathways impinging on the N-terminal tails of histones lead to a number of post-translational modifications including acetylation, phosphorylation, poly (ADP-ribosylation), ubiquitination, and methylation. These modifications play critical roles in regulating chromatin structure and gene expression. Histone methyltransferases selectively methylate evolutionarily conserved arginine or lysine residues, primarily in the N-terminal tails of histones H3 and H4. SET7/9 utilizes S-adenosylmethionine to methylate histone H3 at lysine 4. Human SET7/9 is a 366 amino acid protein with observed migration on SDS-PAGE at 49 kDa.
