FIGURE 3.

RIG-I enzymatic activity increases for longer dsRNA. A, purified recombinant RIG-I was incubated with increasing amounts of purified, differently long dsRNA (400 bp, diamonds; 200 bp, inverted triangles; 100 bp, triangles; 40 bp, circles), and generation of inorganic phosphate by ATP hydrolysis was assessed. Dose-response was standardized and fitted using Hill regression. B, RIG-I was incubated with 0.01 pmol of dsRNA of increasing length, and ATPase activity was measured as in A. The values were regressed using standard mass action kinetics, because a Hill model was not significantly more accurate.