Figure 5.

REF2-II stimulates mRNA export directly. (A and B) Xenopus oocyte nuclei were injected with mixtures of ³²P-labeled RNAs and purified recombinant proteins as indicated. RNA samples from total oocytes (T) and nuclear (N) and cytoplasmic (C) fractions were collected immediately after injection (t₀, lanes 1–3) or 90 min after injection and analyzed as in Fig. 3. The concentration of recombinant proteins in the injected was 14 μM. On the left of B, the numbers in brackets indicate the size of the transcripts. The stimulation of Ad-mRNA export obtained in three separate experiments was quantitated and expressed as fractional stimulation relative to the export activity in the absence of recombinant REF2-II. The mean value was (3.6 ± 0.4)-fold stimulation of export.