This SAM-dependent C-methyltransferase performs the middle step of a three step conversion from arginine to beta-methylarginine. It performs a C-methylation at position 3 of 5-guanidino-2-oxopentanoic acid (keto-arginine). An aminotransferase converts arginine to 5-guanidino-2-oxopentanoic acid, and later converts 5-guanidino-3-methyl-2-oxopentanoic acid to beta-methylarginine.
Jiyao W et al.(2023). "The conserved domain database in 2023.",