For frameshifting sites, the slippery sequence is underlined. In-frame control sequences corresponding to each target sequence are indicated by ‘_if’. For −1 frameshifting, a C was added within the slippery sequence; for +1 frameshifting, the T of the TGA stop codon was removed; and for stop codon readthrough, the stop codon was replaced by AAG. The dnaX and prfB frameshifting sites were also obtained with a specific CACCAC oRibo-T SD sequence (called oSD) upstream from the slippery sequence (dnaXoSD and prfBoSD, respectively). The SmaI site used for stem-loop (SL) cloning is indicated in bold typeface. To allow translation of the F-luc gene after frameshifting, the UGA stop codon in the −1 frame of the dnaX frameshifting site was changed to an UGU codon.