FIG. 3.
Sequences upstream of AATAAA enhance processing efficiency at the RTBV site. (A) The RTBV sequence in RTPA-S up to the site of poly(A) addition is shown. Arrowheads mark the endpoints of the ExoIII deletion series, with the number of nucleotides remaining upstream of the cleavage site and the corresponding processing efficiency indicated. (B) Representative RNase T1 protection assay of the deletion series shown in panel A. Protected fragments corresponding to transcripts processed at the RTBV, cryptic nos, and nos sites are indicated, with the positions of size markers (pBR322/HpaII) shown on the right. Processing efficiencies at the RTBV site are shown in the chart underneath (error bars represent standard deviations). The gel shown is from analysis of RNA from N. plumbaginifolia protoplasts.