FIG. 5.

Effect of high ionic strength on VSV G protein conformational changes during interaction with liposomes. (A) Intrinsic fluorescence of VSV was recorded after virus incubation with vesicles composed of PC-PS (1:3) in the absence (•) and in the presence (○) of 250 mM KCl. The vesicles were prepared in 20 mM MES-30 mM Tris buffer, pH 6.0, in a final phospholipid concentration of 0.1 mM. The excitation wavelength was 280 nm, and the emission was collected at 334 nm. The final protein concentration was 70 μg/ml. (B) VSV-induced membrane fusion measured as in Fig. 4 after virus incubation with vesicles composed of PC-PS (1:3) in the absence (•) and in the presence (○) of 250 mM KCl. Experimental conditions were the same as described in the legend to panel A.