Fig. 5: Ion transport measurements in large unilamellar vesicles.

The non-electrogenic Na⁺/K⁺ exchange model (a). Validation of the NMR measurements at different internal and external ²³Na⁺ concentrations. For ²³Na, 1 mM Dy(PPP)₂⁷⁻ chemical shift reagent was added (b). Initial exchange rates observed for AMPs in the Na⁺/K⁺ gradient model (c). The initial exchange rate is estimated by the slope of the linear regression to the first four data points. The error bars indicate the standard error of slope. Representative time-dependent exchange curve for PGLa in the Na⁺/K⁺ gradient model (d). The non-electrogenic Cl⁻/H₂PO₄⁻ exchange model (e). Validation of the NMR measurements at different internal and external ³¹P concentrations, no shift reagent was needed for ³¹P (f). Initial exchange rates observed for AMPs in the Cl⁻/H₂PO₄⁻ gradient model (g). The initial exchange rate is estimated by the slope of the linear regression to the first three data points. The error bars indicate the standard error of slope. Representative time-dependent exchange curve for BUF2 in the Cl⁻/H₂PO₄⁻ gradient model (h).