Fig. 6. (A) Phenyl-mercuric gel electrophoresis of mt tRNAs^Lys with and without the 2-thio group. Lane 1, bovine mt tRNA^Lys with τm⁵s²U (wild type); lane 2, bovine mt tRNA^Lys with τm⁵U (modification intermediate); lane 3, transcript of bovine mt tRNA^Lys. 5′-³²P-labeled tRNAs (0.125 pmol) were loaded onto the gel and visualized by an image analyzer (Fuji Photo Film). The different intensity of each band is due to the labeling efficiency. (B) Binding affinity of bovine mt tRNAs^Lys with and without the 2-thio group for the AAA codon- programmed ribosomal small subunit. The average values for three independent experiments are plotted; bars indicate the SD.