Amber, opal, and frameshift suppressor tRNAs tested at β9′. All tRNA 74 mer or -dCA (7.5 ng per oocyte) average currents were normalized to THG73 74 mer or -dCA average currents, respectively. Black bars are tRNA 74 mer+β9′(UAG, UGA, CGGG, or GGGU) and gray bars are tRNA-dCA (76 mer)+β9′(UAG, UGA, CGGG, or GGGU) in Xenopus Express oocytes. White and hatched bars are tRNA 74 mer and 76 mer, respectively, in Nasco oocytes. Total of tested oocytes is 276, where 17>n>5. TQAS′ and TQAS show significantly reduced aminoacylation in Xenopus Express and Nasco oocytes, respectively, when compared to THG73. Both opal suppressor tRNAs (TQOpS′ and TQOpS) show less aminoacylation than THG73. Overall, the frameshift suppressor YFaFSACCC is the most orthogonal tRNA in both Xenopus Express and Nasco oocytes.