cytidine(34) in tRNA precursor + S-adenosyl-L-methionine => 5-methylcytidine(34) in tRNA precursor + S-adenosyl-L-homocysteine + H(+)
cytidine(34) in trna precursor + s-adenosyl-l-methionine => 5-methylcytidine(34) in trna precursor + s-adenosyl-l-homocysteine + h(+)