FIGURE 4.

Comparison of translation from defective PTV IRES elements in mono- and dicistronic plasmids. The indicated monocistronic (Rluc alone) and dicistronic plasmids (Fluc/Rluc) containing the wild-type (A) or mutant (B) forms of the PTV IRES were assayed in parallel alone (−) or with (+) pGEM3Z/J1 (as for Fig. 1B). Cell extracts were prepared and analyzed for Fluc and Rluc expression as shown. Results are from one experiment but very similar results were observed in a second assay of the same set of plasmids.