FIG. 5.

Competitive binding assay between Cry1Aa and its inactive mutants. Permeability of the vesicles to KCl was assayed as described in the legend to Fig. 4, except that the toxins were not preincubated with the vesicles but were mixed with the KCl solution prior to the osmotic shock. The concentrations (Cry1Aa-to-mutant ratios) are in pmol of toxin/mg of membrane protein. The percent volume recovery was calculated for every experimental point, and values obtained for control vesicles, assayed without added toxin, were subtracted from those obtained in the presence of toxin. For clarity, error bars are shown for every 50th experimental point.