Fig. 1.
Effect of ESEs on U1 RNA export. (A) Schematic representation of U1-ESE derivatives used for the export analysis. One or multiple copies of purine-rich ESE sequences from various genes were inserted into U1ΔSm RNA. (B) A mixture of in vitro-transcribed 32P-labeled RNAs containing U1-ESE, U1ΔSm, and U6Δss RNAs was injected into the nucleus of Xenopus oocytes. U6Δss RNA was uncapped, and all of the other RNAs were m7G-capped. RNA was extracted from nuclear (N) and cytoplasmic (C) fractions immediately (0 h; lanes 1, 2, 5, 6, 9, 10, 13, and 14) or 1 h (1 h; lanes 3, 4, 7, 8, 11, 12, 15, and 16) after injection and analyzed by 8% denaturing PAGE. (C) Quantitation of RNA export from three independent experiments as in B. Averages and standard deviations are shown. (D) The same as in B except that one to three copies of ASLV ESE were used. (E) Quantitation of D.