FIG. 4.

Efficient polyadenylation of P41-driven transcripts at (pA)p requires a downstream element that overlaps with the A2 3′ splice acceptor site and competes with the splicing process. 293 cells were transfected with the P41Cap (diagrammed on the right) and the P41CapA2CAA-based plasmids, which contain various mutations (diagrammed in Fig. 3) of the A2 3′ splice acceptor site. Total RNA was protected by homologous DH probes, and a representative experiment is shown with the identities of the protected bands on the right. Quanitification of the ratios of RNAs polyadenylated at (pA)p relative to the total protected RNAs are shown as averages with the standard deviations and are results of at least three individual experiments. RNA from uninfected cells generated no protection products.