Fig. 2.
Transient currents obtained at 2 different LPR (10 and 5). The solution exchange protocol and the nonactivating solution were as described in Fig. 1, but the activating solution contained 40 mM glucose plus 10 mM lactose. Therefore, the difference between the test and nonactivating solutions represents a 10 mM lactose concentration jump (10 mM ΔLactose). Wild-type LacY proteoliposomes reconstituted at a LPR of 10 (≈1,000 particles per μm2; Fig. S2A) or at a LPR of 5 (≈4,500 particles per μm2; Fig. S2B) were activated with a 10 mM lactose concentration jump. The decay phase of the transient currents is decreased almost 5-fold from a τ1/2 = 53 ± 2 ms at an LPR of 5 (black trace) to a τ1/2 = 260 ± 2 ms at an LPR of 10 (gray trace).