Also known as MNMG_ACTP2, mnmG, gidA. NAD-binding protein involved in the addition of a carboxymethylaminomethyl (cmnm) group at the wobble position (U34) of certain tRNAs, forming tRNA-cmnm(5)s(2)U34. Homodimer. Heterotetramer of two MnmE and two MnmG subunits.