TRNA (adenine<sup>9</sup>-N<sup>1</sup>)-methyltransferase (, Trm10p, tRNA(m1G9/m1A9)-methyltransferase, tRNA(m1G9/m1A9)MTase, TK0422p (gene), tRNA m1A9-methyltransferase, tRNA m1A9 Mtase) is an enzyme with systematic name S-adenosyl-L-methionine:tRNA (adenine<sup>9</sup>-N<sup>1</sup>)-methyltransferase. This enzyme catalyses the following chemical reaction
The enzyme from Sulfolobus acidocaldarius specifically methylates adenine<sup>9</sup> in tRNA.