Fig. 4. Ligand-gated ion transportation of membrane-embedded multiblock amphiphile.

a Changes in the 510-nm fluorescence intensity of HPTS encapsulated in DOPC•2mer^post LUVs in HEPES buffer containing PA at 20 °C as a function of time after the addition of (red) LiOH, (orange) NaOH and (blue) KOH at 0 sec followed by addition of 1.0 wt% Triton X-100 at 100 sec ([DOPC] = 400 μM, [2mer] = 0.75 μM, [PA] = 10 mM, [HPTS] = 30 μM, 20 mM HEPES, 50 mM KCl, pH 7.1, excitation at λ = 460 nm, emission at λ = 510 nm). The black broken and solid lines show changes in the fluorescence intensities of HPTS encapsulated in (broken) DOPC•2mer^post LUVs and (solid) DOPC•2mer^post LUVs containing PA in the intravesicular medium in HEPES buffer in the absence of PA in the extravesicular medium upon addition of LiOH. ΔpH = 0.8 (7.1–7.9). b Plots of relative 510-nm fluorescence intensities of HPTS encapsulated in DOPC•2mer^post LUVs at 20 s after the addition of KOH in 20 mM HEPES buffer containing 50 mM KCl at 20 °C as a function of the concentration of 2mer ([DOPC] = 400 μM, [PA] = 10 mM, [HPTS] = 30 μM). Curve-fitting analyses were carried out by the Hill equation. c, d Current traces at the applied voltage of 100 mV of a DOPC•2mer^post BLM ([DOPC]/[2mer] = 60,000/1) in HEPES buffer (20 mM HEPES, 50 mM KCl, 2.0 mM MgCl₂, pH 7.5) c before and d after addition of PA (200 nM) at 20 °C.