FIGURE 2.

Pk1 of the E. coli tmRNA and its mutants. Pk1 is shown with abutting helix 2d. An open square and an open circle denote nucleotides C44 and C66, respectively. Open rectangles highlight mutations of G50C to C50G base pair. Open ovals mark the resume codon (GCA). Arrows indicate deletion sites of nucleotides 54–72 and 69–78 in the pk1L and Δh4/Δ69–78 mutants, respectively. Slanted lines mark deletions of a single base pair, 2 bp, and 3 bp in Δh4/Δ1p, Δh4/Δ2p, and Δh4/Δ3p, respectively. Numbering is according to E. coli tmRNA.