Methyltransferase involved in methanogenesis from methylamines methanol pathway. Catalyzes the transfer of the methyl group from the methylated corrinoid protein MtmC (MtmC1 or MtmC2) or MtbC to coenzyme M, forming the substrate for coenzyme-B sulfoethylthiotransferase. coenzyme M + methyl-Co(III)-[methylamine-specific corrinoid protein] = Co(I)-[methylamine-specific corrinoid protein] + H(+) + methyl-coenzyme M Inhibited by EDTA and EGTA. One-carbon metabolism; methanogenesis from methylated amine. Copurifies with MtbC. Belongs to the uroporphyrinogen decarboxylase family. MtbA/MtaA subfamily.