label: cytidine(50) in tRNA + S-adenosyl-L-methionine <=> 5-methylcytidine(50) in tRNA + S-adenosyl-L-homocysteine + H(+)
label_lc: cytidine(50) in trna + s-adenosyl-l-methionine <=> 5-methylcytidine(50) in trna + s-adenosyl-l-homocysteine + h(+)