Figure 1

Secondary structure of E. coli tmRNA. Phylogenetically-supported helices are highlighted in gray and numbered from 1 to 12. The 5' and 3' ends are indicated. Arrows represent connections from 5' to 3'. Residues are numbered in increments of ten. Weakly supported regions and basepairs are shown in boxes. The disproved potential pairing of C109 with G136 is labeled with an open arrowhead. The star labels the first nucleotide of the resume codon. The tag peptide sequence is shown below the mRNA-like region. The stop codons are indicated with solid arrowheads. Three domains are distinguished: the tRNA-like domain (TLD), the mRNA-like domain (MLD), and the pseudoknot domain (PKD).