Figure 3

A. Representative gel mobility shift analysis of U1A protein binding to WT, A1-2AP, C10A, and A1G-C10A SL2 RNAs. The highest protein concentration used for the assays was 7 μM, and a 1:3 serial dilution was performed. B.-D. Plots illustrating the fraction RNA bound as a function of U1A concentration. B. Binding experiments performed with SL2 RNAs in which A1 was substituted with P, I, DAP, 2AP, and G. Binding curves for C10A and A1G-C10A are also included in this plot. C. Binding experiments performed with SL2 RNAs in which G4 was substituted with I, c7dG, DAP, 2AP, and A. D. Binding experiments performed with SL2 RNAs in which A6 was substituted with DAP, 2AP, and I.