FIG. 2.

Products of cell-free translation reactions programmed with synthetic dicistronic RNA transcripts containing the poliovirus 5′NTR within the intercistronic space (Fig. 1A). Reaction mixes (25 μl) were programmed with 1 μg of the indicated T7 transcripts (lanes 2 to 5) or no RNA (lane 1). Intact PTB appears as a doublet band with an apparent molecular mass of ∼57 kDa (lane 2), while mutant PTBs appear as more rapidly migrating doublet bands (lanes 3 and 5). No PTB product is evident from translation of the null mutant, pΔ87-531/SC (lane 4), consistent with the small predicted size of this product (∼10.7 kDa). CAT is produced from all four transcripts and migrates with an apparent molecular mass of ∼24 kDa (lanes 2 to 5).