Mitochondrial DNA is multicopy and maternally inherited. mtDNA has 16,500 basepairs and codes for 37 genes; 13 polypeptides, 22 transfer RNA (tRNA) and two ribosomal RNA (rRNA). Transfer RNAs (tRNAs) are key molecules in protein biosynthesis in all living organisms. They have specific structural properties allowing interactions with several partners such as their cognate aminoacyl-tRNA synthetases (aaRSs), elongation factor, mRNA or ribosome. MT-TS1 is a small 69 nucleotide RNA that transfers the amino acid serine into the growing polypeptide chain at the ribosome site of protein synthesis during translation.