N(2)-dimethylguanosine(10) in tRNA + S-adenosyl-L-homocysteine + H(+) => N(2)-methylguanosine(10) in tRNA + S-adenosyl-L-methionine
n(2)-dimethylguanosine(10) in trna + s-adenosyl-l-homocysteine + h(+) => n(2)-methylguanosine(10) in trna + s-adenosyl-l-methionine