Figure 7.

Unimpaired import of snRNPs and small RNAs in the presence of anti-xNup98 antibodies. Oocytes that had been pre-injected with antibodies or WGA, as in Fig. 6, were injected in the cytoplasm with a mixture of ³²P-labeled U1_Sm−, U1_Δ, U5, and NL15 RNAs that were made by in vitro transcription. After 7 h of incubation, import of the RNAs was monitored by polyacrylamide gel analysis of 0.5 oocyte equivalents of nuclear RNAs isolated from pools of 3–5 oocyte nuclei. The mixture of injected RNAs (Inj.) is shown in lane 1; the slightly faster gel mobilities of U1_Δ (a mutant U1 RNA lacking the U1A protein binding site) and U5 RNAs in lanes 2–4 are due to 3′ end trimming which occurs upon nuclear import of snRNPs (Neuman de Vegvar and Dahlberg, 1990). U1_Sm− RNA lacks the Sm binding site required for import and serves as a control for cytoplasmic contamination of the nuclear samples. Cytoplasmic fractions are not shown, as RNA levels were in excess, and differences among them were not significant.