A, Misreading (A) were measured by dual luciferase gain-of-function assays using wild-type mitohybrid ribosomes (n=8 misreading, mutant A1555G mitohybrid ribosomes (n=8 misreading, E. coli wild-type ribosomes (n=9), E.coli mutant A127Y ribosomes (n=9), M. smegmatis merodiploid wild-type ribosomes (n=9), and M. smegmatis merodiploid mutant S152Y ribosomes (n=9). Mistranslation was determined by assessing the misreading at His245 (CAC codon) of the F-luc gene that was replaced by the near-cognate codon CGC or the non-cognate codon AGA, both encoding for Arg. Results are derived by calculating mutant hFluc/hRluc activity related to wild-type hFluc/hRluc activity. 