This family contains a SAM (S-adenosyl methyltransferase) domain, with a central beta sheet with 3 alpha-helices on both sides. Crystal packing analysis of the structure PDB:3giw from Swiss:Q82L35 suggests that a monomer is the solution state oligomeric form. An unidentified ligand (UNL, cyan) was found at the putative active site surrounded by the residues His57, His170, Phe171, Tyr216 and Met22 . The UNL is likely to be a phenylalanine or phenylalanine-like molecule. (details derived from TOPSAN).

1: The histamine N-methyltransferase T105I polymorphism affects active site structure and dynamics. Rutherford K, Parson WW, Daggett V; Biochemistry. 2008;47:893-901. PMID:18154359