Figure 1.

Comparison of the structures of (a) tRNA, (b) mRNA and (c) tmRNA. (a, c) The 3' and 5' termini, the amino acid acceptor stem (AC) and the anticodon (A), D and T arms are indicated. (b, c) The Shine-Dalgarno sequence (SD), the start codon (s) and the stop codon (octagon), the locations of the tRNA-like (TLD) and mRNA-like domains (MLD) as well as pseudoknots (pk) 1 to 4, helix 5 (h5), and the +1 resume codon (r) are indicated. The thin arrows depict the pseudoknot connections.