FIGURE 6.

(A) Primer extension assay of pre-mRNA stability following the inactivation of RNA polymerase II in isogenic strains containing UPF1 or upf1Δ. Bands corresponding to unspliced pre-mRNA from the splicing reporter were quantified and normalized to a polymerase III transcript, 7S RNA, and plotted as the percent RNA remaining from time zero in B from five separate experiments. (C) A plot for the decay of full-length AMA1 RNA after inactivation of RNA polymerase II in isogenic strains containing or lacking UPF1. The data are averages from two independent trials.