Implication of segment S45 in the permeation pathway of voltage-dependent sodium channels.

摘要: A 34-mer peptide, encompassing the S4 and S45 segments of domain IV electric eel voltage-dependent sodium channel, was synthesized in order to test potential implication gating or permeation pathway. The secondary structure peptide S4–S45 assessed by circular dichroism found mainly helical, both organic solvents lipid vesicles, especially negatively-charged ones. macroscopic conductance properties neutral Montal-Mueller planar bilayers doped with were studied compared those S4. With regard voltage-dependence, most efficient system bilayers. Voltage thresholds for exponential development correlate background “leak” conductance. Assuming that latter reflects interfacial concentration, mean apparent number monomers per conducting aggregate could be estimated 3–5. In single-channel experiments, probable events had amplitudes 8 pS 5 respectively. Ionic selectivity under salt gradients conditions, at levels, favour ions (PNa/PK = 3). These compare favourably previous reports dealing modelling transmembrane ionic channels. Specifically, when alone, reduced unit increased support region inner lining open configuration