Figure 4.

The 16-nt G-tract element ‘TGGGGTAAACTGGGGT’ is essential for Bcl-xL and sufficient for a heterologous exon to be repressed by Ro. Shown are agrose gels of RT-PCR products of HEK293T cells transfected with splicing reporter minigenes with the element sequences and splicing patterns indicated above the gels. Bar graphs of the average percent (± SD, n = 3) exon exclusion for each sample are below the gels. The dotted horizontal lines mark the exon exclusion levels of the vectors. Cells were treated with 2 µg/ml Ro or nontreated (NT) for overnight. *A cryptic 5′ splice product with 38-nt deletion at the 3′ end of the middle exon (as indicated by the dotted line in the diagram above the gel); **likely heteroduplex formed between the two splice variant products; open triangle, same as in Figure 2.