FIG. 2.

Inhibition of Ca.LSU intron splicing by pentamidine analogs. Reactions were run under standard conditions as indicated in Materials and Methods. The first lane (T) shows precursor RNA only, the second lane (+) shows the complete reaction without drugs, and the third lane (−) shows the reaction in the absence of magnesium and GTP. The experimental compounds are present in a complete splicing reaction at the following concentrations (from left to right): 0.125, 0.25, 0.5, or 0.75 μM BBE; 5, 10, 20, 40, or 60 μM DIMP; 5, 10, 30, or 60 μM tetracycline; 0.5, 0.75, 1.0, or 1.25 μM propamidine; and 100, 150, 200, or 250 μM pentamidine. The bands are labeled as follows: P, precursor RNA; I-E2, G intron-3′ exon intermediate; I, excised linear G intron; E1-E2, reaction product consisting of ligated exon fragments; E1, 5′ exon fragment intermediate.