FIGURE 4.

(A) The image plot of [Ca] in the plane y = 0 (x,z cross section of Fig. 1 A) after a sustained opening of the channel for 0.3 ms in the presence of the vesicle. (B) The image plot of [Ca] in the plane z = 0 (x,y cross section of Fig. 1 A) after a sustained opening of the channel for 0.3 ms in the presence of the vesicle. (C) [Ca] in the presence of the vesicle A minus [Ca] in the absence of the vesicle. (D) [Ca] in the presence of vesicle B minus [Ca] in the absence of the vesicle. The black circles in B and D are the projection of the vesicle on the membrane, whereas the red circles correspond to possible positions for the Ca²⁺-sensor.