BacteriorhodopsinsHalobacteriumCell MembraneSchiff BasesSodium-Potassium-Exchanging ATPaseRubidiumAmino Acid SequenceProtein Structure, SecondaryMolecular Sequence DataExtracellular SpaceModels, MolecularBinding SitesProtein ConformationKineticsMutagenesis, Site-DirectedMembrane ProteinsProtein Structure, TertiarySodiumIon ChannelsLigandsHydrogen-Ion ConcentrationMembrane PotentialsAdenosine TriphosphateElectrophysiology