Figure 1.

Inhibition of mRNA and snRNA export by the PKI NES conjugate. The PKI and REV NES conjugates differ in their abilities to inhibit RNA export. One to three femtomoles of each ³²P-labeled DHFR mRNA, AdML pre-mRNA, U3 snRNA, U1_Sm− snRNA, and tRNA_i^Met were coinjected into oocyte nuclei together with ≈20 ng per nucleus of the PKI NES (lanes 2–7), MIX (lanes 8–13), REV NES (lanes 14–19), or M10 (lanes 20–25) peptide conjugates (see Table 1). The oocytes were dissected 1, 4, and 20 hr after injection, and RNA was extracted from the nuclear (N) and cytoplasmic (C) fractions; 0.5 oocyte equivalent of RNA was resolved on denaturing 8% polyacrylamide gels and visualized by autoradiography. The AdML mRNA and tRNA_i^Met panels were exposed twice as long as the upper panels, to allow for detection of AdML mRNA export. The triangles at the top of the lanes indicate increasing times since injection. U3 snRNA, which normally is not exported from the nucleus (24), served as a marker for the accuracy of nuclear injections and oocyte dissections. The RNA injection mixture (I) is shown in lane 1. Pre-AdML RNA is the injected form of the intron-containing pre-mRNA; the lariat symbol represents the excised AdML intron, and AdML represents the spliced mRNA, which normally is exported from the nucleus.