E Quantification of MT-CO1 proteins in HEK293 MRPS5 wild-type cells and HEK293 MRPS5 mutant V336Y cells. In-organello mitochondrial translation in the presence of 35S-Met and 750 µM tobramycin. Proteins were loaded either directly on SDS-PAGE (total) or following poly-lysine immunoprecipitation and analyzed by autoradiography. For total protein samples the MT-CO1 band was quantified, for poly-lysine immunoprecipitated samples the extended MT-CO1 band was quantified and the ratio of extended MT-CO1/total MT-CO1 calculated. The ratio of MRPS5 wild-type was set as 1 (MRPS5 wild-type, n=5 clones, MRPS5 V336Y, n=7 clones), error bars indicate SD; ***p<0.0001 (Student's t-test). 