Fig. 4: Membrane polarisation measurements in large unilamellar vesicles.

Scheme of the Na⁺/K⁺ gradient model with oxonol VI in the membrane (lilac circles) (a). Representative fluorescence change of oxonol VI upon adding PGLa (at t = 0) to the Na⁺/K⁺ gradient system. The negative change indicates a positive inside potential (b). AMP-induced fluorescence intensity decreases, implying the diffusion potential for the K⁺/Na⁺ gradient model (red), n = 40 (c). Schematic of the Cl⁻/H₂PO₄⁻ gradient model with oxonol VI in the membrane (lilac circles) (d). Representative fluorescence change of oxonol VI upon adding PGLa (at t = 0) to the Cl⁻/H₂PO₄⁻ gradient system (e). AMP-induced fluorescence intensity decreases, indicating the diffusion potential for the Cl⁻/H₂PO₄⁻ gradient model (blue), n = 40 (f).