In enzymology, a methylamine-glutamate N-methyltransferase (EC 2.1.1.21) is an enzyme that catalyzes the chemical reaction

methylamine + l-glutamate ${\displaystyle \rightleftharpoons }$ NH₃ + N-methyl-l-glutamate

Thus, the two substrates of this enzyme are methylamine and l-glutamate, whereas its two products are NH₃ and N-methyl-l-glutamate.

This enzyme belongs to the family of transferases, specifically those transferring one-carbon group methyltransferases. The systematic name of this enzyme class is methylamine:l-glutamate N-methyltransferase. Other names in common use include N-methylglutamate synthase, and methylamine-glutamate methyltransferase. This enzyme participates in methane metabolism.

• Shaw WV, Tsai L, Stadtman ER (1966). "The enzymatic synthesis of N-methylglutamic acid". J. Biol. Chem. 241 (4): 935–45. PMID 5905132.