scholarly journals Ion Transport Through Excitability-Inducing Material (EIM) Channels in Lipid Bilayer Membranes

1972 ◽  
Vol 60 (1) ◽  
pp. 72-85 ◽  
Author(s):  
Ramon Latorre ◽  
Gerald Ehrenstein ◽  
Harold Lecar
Keyword(s):  
Aqueous Solution ◽  
Ion Transport ◽  
Lipid Bilayers ◽  
Voltage Dependence ◽  
The Other ◽  
Lipid Bilayer Membranes ◽  
Relative Permeabilities ◽  
Bilayer Membranes ◽  
Voltage Dependent ◽  
Ionic Mobilities

Two different methods were used to determine the relative permeability and the voltage-dependent conductance of several different cations in excitability-inducing material (EIM)-doped lipid bilayers. In one method, the conductances of individual channels were measured for Li, Na, K, Cs, NH4, and Ca, and in the other method biionic potentials of a membrane with many channels were measured for Li, Na, K, Cs, and Rb. The experimental results for the two methods are in agreement. The relative permeabilities are proportional to the ionic mobilities in free aqueous solution. The voltage dependence of the conductance is the same for all cations measured.

Carrier-mediated ion transport in lipid bilayer membranes

1984 ◽  
Vol 62 (8) ◽  
pp. 738-751 ◽  
Author(s):  
Raynald Laprade ◽  
François Grenier ◽  
Monique Pagé-Dansereau ◽  
Janine Dansereau
Keyword(s):  
Steady State ◽  
Ion Transport ◽  
Lipid Bilayers ◽  
Aqueous Phase ◽  
Rate Constants ◽  
The Other ◽  
Electrostatic Energy ◽  
Membrane Thickness ◽  
Lipid Bilayer Membranes ◽  
Electrical Measurements

The electrical properties predicted by a widely accepted model for carrier-mediated ion transport in lipid bilayers are described. The different steps leading to ion transport and their associated rate constants are reaction at the interface between an ion in the aqueous phase and a carrier in the membrane (kRi), followed by translocation of the ion–carrier complex across the membrane interior (kis) and its dissociation at the other interface (kDi) after which the free carrier crosses back the membrane interior (ks). Results on glyceryl monooleate (GMO) membranes for a family of homologue carriers, the macrotetralide actin antibiotics (nonactin, monactin, dinactin, trinactin, and tetranactin) and a variety of ions (Na+, Cs+, Rb+, K+, NH4+, and Tl+) are presented. Internally consistent data obtained from steady-state electrical measurements (zero-current potential and conductance, current-voltage relationship) allow us to obtain the equilibrium permeability ratios for the different ions and show that for a given carrier kRi is relatively invariant from one ion to the other, except for Tl+ (larger), which implies that the ionic selectivity is controlled by the dissociation of the complex. The values of the individual rate constants obtained from current relaxation experiments are also presented and confirm the findings from steady-state measurements, as well as the isostericity concept for complexes of different ions with the same carrier (kis invariant). These also allow us to determine the aqueous phase membrane and torus membrane partition coefficients. Finally, the observed increase in kis from nonactin to tetranactin and, for all homologues, from GMO–decane to solvent-free GMO membranes, together with the concomitant decrease in kDi, can be explained in terms of modifications of electrostatic energy profiles induced by variations in carrier size and membrane thickness.

Lysenin forms a voltage-dependent channel in artificial lipid bilayer membranes

2006 ◽  
Vol 346 (1) ◽  
pp. 288-292 ◽  
Author(s):  
Toru Ide ◽  
Takaaki Aoki ◽  
Yuko Takeuchi ◽  
Toshio Yanagida
Keyword(s):  
Lipid Bilayer ◽  
Lipid Bilayer Membranes ◽  
Bilayer Membranes ◽  
Voltage Dependent

Charge transport of ion pumps on lipid bilayer membranes

1993 ◽  
Vol 26 (1) ◽  
pp. 1-25 ◽  
Author(s):  
E. Bamberg ◽  
H.-J. Butt ◽  
A. Eisenrauch ◽  
K. Fendler
Keyword(s):  
Amino Acids ◽  
Ion Channels ◽  
Ion Transport ◽  
Charge Transport ◽  
Cell Types ◽  
Ion Pumps ◽  
Lipid Bilayer Membranes ◽  
Bilayer Membranes ◽  
Ion Gradients ◽  
Cotransport Systems

Ion pumps create ion gradients across cell membranes while consuming light energy or chemical energy. The ion gradients are used by the corresponding cell types for passive-ion transport via ion channels or carriers or for accumulation of nutrients like sugar or amino acids via cotransport systems or antiporters.

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