Molecular function

protein arginine omega-N monomethylase activity

Catalysis of the addition of a methyl group to either of the unmethylated terminal nitrogen atoms (also called omega nitrogen) in peptidyl-arginine to form an omega-N-G-monomethylated arginine residue. The reaction is S-adenosyl-L-methionine + [protein]-L-arginine = S-adenosyl-L-homocysteine + [protein]-Nomega-methyl-L-arginine.

S-adenosyl-L-methionine:[protein]-L-arginine N-methyltransferase ([protein]-Nomega-methyl-L-arginine-forming), type III protein arginine methyltransferase activity

Type III protein arginine methyltransferases catalyze the single methylation of one of the terminal nitrogen atoms of the guanidino group in an L-arginine residue within a protein. Unlike type I and type II protein arginine methyltransferases, which also catalyze this reaction, type III enzymes do not methylate the substrate any further.