FIGURE 6.

Processing of expanded introns. (A) Transcription–splicing reactions were carried out for 2 h on the β-globin templates encoding RNAs with varying length of the intron (indicated on top of the panel). Where indicated, transcription was allowed to proceed for 15 min, at which point the incubations were interrupted and α-amanitin was added to a final concentration of 1 ng/μL. The samples were incubated further for a total of 2 h. The precursors and products of the splicing reactions are indicated to the left of the panel. (B) The corresponding splicing assay using substrates with varying length of the intron (indicated on top of the panel). Samples were incubated for 2 h. The precursors and products of the splicing reactions are indicated on the left of the panel, except in the case of ßglobin-ΔInt construct (849-nt intron), where precursors and intermediates are indicated on the right.