FIGURE 5.

Cap-dependent translation of monocistronic mRNAs containing defective AEV IRES elements. (A) Plasmids encoding monocistronic mRNAs containing the wild-type or mutant forms of the AEV IRES were transfected alone (−) or with (+) pGEM3Z/J1 into vTF7-3 infected BHK cells (as for Fig. 1B). Cell extracts were analyzed for Rluc expression by immunoblotting and by enzyme assay (results are the mean +S.D. for three or four independent transfections). (B) The indicated cell extracts were reanalyzed to facilitate comparison of the Rluc products expressed from plasmids containing the wild-type or mutant AEV IRES in the sense or antisense (AS) orientation. The Rluc and a nonspecific background band (NSB) are indicated on the blots.