Figure 4.

gBP21 has a low affinity for dsRNA. Radiolabeled gRNA gA6-14 was bound to gBP21 and incubated with increasing amounts of a 55 bp dsRNA as a competitor RNA. The amount of bound gRNA was determined by filter binding and plotted as a function of the competitor concentration. The data were fitted as outlined in the Materials and Methods to derive a K_d value of 800 nM (filled triangles). Control competition experiments were performed with the homologous competitor gA6-14 (filled squares, K_d = 8 nM) and tRNA^Phe as a non-homologous RNA (open triangles, K_d = 100 nM).