FIG. 4.

Effect of dr1 mutations on cytoplasmic accumulation of unspliced viral RNA. QT6 cells were transfected with 10 μg of the mutant DNAs in a subgroup B background to prevent reinfection. A total of 10 μg of plasmid pMyc23 was included as a transfection control. RNase protection assays were performed by using total, nuclear, and cytoplasmic RNA preparations isolated 40 h after transfection with the radiolabeled riboprobe shown in Fig. 1, as well as a riboprobe specific for myc. (A) Schematic diagram of riboprobe and protected RNA species. The thin dashed line indicates vector sequences. The sizes of the riboprobe and the protected fragments are indicated. (B) RNase protection of fractionated cellular RNA. The asterisks indicate bands that arise from protection of the probe by both ends of the same RNA molecule or by two ends from two different RNA molecules.