Figure 5. MSCRs derived from 5UI⁻ genes promote mRNA nuclear export.

Transcripts encoding various versions of ftz (see Figure S4 for all modified ftz sequences) were microinjected along with fluorescent 70 kD dextran as in Figure 3. Panels A and B are as described for Figure 3. (C) DNA plasmids containing the indicated ftz genes and fluorescent 70 kD dextran were microinjected alone, or with the CTE viral RNA, into the nuclei of NIH 3T3 fibroblasts. Cells were allowed to express the ftz RNAs for 20 min then further transcription was inhibited by α-amanitin treatment. After allowing the mRNA to be exported for 2 hours, the cells were fixed and ftz mRNA was detected by fluorescence in situ hybridization. The distribution of ftz mRNA was quantified as described in Figure 3B.