Figure 4.

Time course of ΔpH-dependent 10-μm ⁴⁵Ca²⁺ transport into endomembrane-enriched vesicles prepared from K667 mutant yeast expressing either A, sCAX1; B, lCAX1; or C, vector alone. Ca²⁺ transport was determined in the absence (▴) or presence (●) of 5 μm gramicidin. Ca²⁺ transport in the presence of gramicidin was not determined for the first two time points. All time course experiments were performed in the presence of 0.1 mm NaN₃, 0.2 mm Na orthovanadate, and 1 mm ATP. The Ca²⁺ ionophore A23187 (5 μm) was added at the times indicated (arrow). Results are the average (±se) of three independent experiments.