FIG. 2.

Putative frameshift region in the ISRgn1 RNA, including a predicted stem-loop structure with a ΔG of −12.9 kcal/mol (19). Only one of several possible secondary structures is shown for simplicity. The putative RBS of OrfB is underlined twice, and the proposed frameshift heptanucleotide is in bold. Codons indicated above the RNA sequence correspond to the product of direct translational readout from the ORFA start codon. Those below correspond to the product of a −1 translational frameshift. The ORFA stop codon is circled.