L-glutaminyl-[peptide chain release factor] + S-adenosyl-L-methionine => N(5)-methyl-L-glutaminyl-[peptide chain release factor] + S-adenosyl-L-homocysteine + H(+)
l-glutaminyl-[peptide chain release factor] + s-adenosyl-l-methionine => n(5)-methyl-l-glutaminyl-[peptide chain release factor] + s-adenosyl-l-homocysteine + h(+)