FIG. 5.

Temperature and cap dependence of nuclear export of U3 mutants. (A) ³²P-labeled U3ΔBD and control RNAs (U1sm− and U8) were injected into the nuclei of Xenopus oocytes. The oocytes were incubated for 8 h at 4 or 18°C. After incubation, the radiolabeled RNAs present in the nuclear (N) and cytoplasmic (C) fractions of the oocytes were isolated and analyzed. (B) ³²P-labeled U3ΔBD with either an m⁷G or ApppG cap structure and control RNAs (U1sm− and U8) were injected into the nucleus. After 8 h of incubation, the radiolabeled RNAs present in the nuclear and cytoplasmic fractions of the oocytes were isolated and analyzed. Marker lanes (M) show the RNAs prior to injection.