FIGURE 4.
Binding of lysenin to SM was dependent upon the local density of SM at the air-water interface. (A) Δπ values reached after injection of lysenin under egg SM/diC18:1 PC (closed circle), egg SM/diC16:0 PC (closed square), or egg SM/GalCer (closed triangle) mixed monolayers with various concentrations of SM at a πi of 21.5 ± 2.0 mN/m. (B) Δπ values reached after injection of lysenin under egg SM/diC18:1 PC (molar ratio1:9), egg SM/diC16:0 PC (1:9), or egg SM/GalCer (1:9) in the absence (solid column) or presence (hatched column) of equimolar cholesterol to SM at πi of 20.9 ± 1 mN/m. Results are the mean of duplicate or triplicate experiments ± difference. (C–F) His-Venus-lysenin was injected into the subphase beneath egg SM/diC18:1 PC (1:9) (C), egg SM/diC16:0 (1:9) (D), egg SM/diC18:1 PC/cholesterol (1:9:1) (E), or egg SM/diC16:0/cholesterol (1:9:1) (F). Fluorescence image was recorded as described in Experimental Procedures. Bar, 20 μm.