This is a family of tRNA (Guanine-1)-methyltransferases EC:2.1.1.31. In E.coli K12 this enzyme catalyses the conversion of a guanosine residue to N1-methylguanine in position 37, next to the anticodon, in tRNA [1].

1: Purification and characterization of transfer RNA (guanine- 1)methyltransferase from Escherichia coli. Hjalmarsson KJ, Bystrom AS, Bjork GR; J Biol Chem 1983;258:1343-1351. PMID:6337136