2.6.1.13 additional information sequence contains a putative N-terminal signal peptide for mitochondrial targeting 689633 2.6.1.13 additional information sequence contains no mitochondrial targeting motif 689114 2.6.1.13 proteolytic modification the human enzyme is synthesized on cytoplasmic free ribosomes as a 45 kDa precursor and is processed into a mature protein after mitochondrial entry 759181