Fig. 1.

Transient currents obtained with wild-type LacY proteoliposomes after a 50 mM sugar concentration jump at t = 1.5 s. The traces in black, red, and green correspond to concentration jumps of lactose (50 mM; ΔLactose), lactulose (50 mM; ΔLactulose), melibiose (50 mM; ΔMelibiose), and sucrose (50 mM; ΔSucrose), respectively. The nonactivating solution (50 mM glucose) and all activating solutions were prepared in 100 mM potassium phosphate at pH 7.6 plus 1 mM DTT. All traces shown were recorded from 1 sensor.