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