Figure 4.

ISE affects turnover of pre-mRNA splicing intermediates. (A) Schematic representation of the hybrid minigenes used to evaluate the splicing intermediates. α-globin and ATM exons are grey and white boxes, respectively, the black box is the 40 bp insertion and introns are lines. The cryptic 65 bp ATM exon (Δ) is indicated. The arrows indicate location of primers used in RT–PCR analysis. (B) Analysis of preS1 intermediate abundance. The indicated minigenes were transfected in HeLa cells (250 ng each) and preS1 intermediate amplified with the primers. In cotransfection experiments equal amount of plasmids (250 ng) were transfected. The splicing products are shown and their identity was verified by direct sequencing.