FIGURE 1.

(A) The genetic code. The eight codon boxes with shaded background are the family codon boxes, containing four codons representing one amino acid (fourfold degenerate). The five family codon boxes in lighter shade contain tRNA having cmo⁵U as a wobble nucleoside. The codon boxes with white background are the mixed codon boxes. (B) The proline family codon box (CCN). proK, L, and M denote the genes encoding tRNA^Pro_CGG, tRNA^Pro_GGG and tRNA^Pro_cmo5UGG, respectively, and the wobble nucleosides, which are present in position 34, are indicated. A circle corresponds to a codon read by a tRNA and a line connecting two or more circles indicates that the same tRNA is able to read those codons (e.g., the proL tRNA contains G34 and reads the CCU and CCC codons). The gray circle for tRNA^Pro_cmo5UGG (codon CCC) indicates that this tRNA reads the CCC codon (results presented in this article), and the black circles show the codon reading abilities predicted by the wobble hypothesis and the revised wobble rules.