Cation Selective Glass Electrodes and their Mode of Operation

Eisenman, George

doi:10.1016/s0006-3495(62)86959-8

Cited by 826 publications

(434 citation statements)

References 38 publications

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“…Eisenman and Sherry sequences allow to characterize ion binding sites within the TJ pore with respect to their electrostatic interaction, which can be interpreted as different degrees of hydration shell removal (Eisenman, 1962;Diamond and Wright, 1969). Bicellular overexpression of TRIC-a resulted in decreased permeabilities to all ions tested, but only minor shifts of Eisenman and Sherry sequences, indicating that TRIC-a does not substantially alter paracellular selectivity for ions.…”

Section: Tricellulin Reduces Btj Ion Permeability Without Change In Smentioning

confidence: 99%

Tricellulin Forms a Barrier to Macromolecules in Tricellular Tight Junctions without Affecting Ion Permeability

Krug

Amasheh

Richter

et al. 2009

MBoC

300

322

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Tricellulin is a tight junction protein localized in tricellular tight junctions (tTJs), the meeting points of three cells, but also in bicellular tight junctions (bTJs). To investigate its specific barrier functions in bTJs and tTJs, TRIC-a was expressed in low-level tricellulin-expressing cells, and MDCK II, either in all TJs or only in tTJs. When expressed in all TJs, tricellulin increased paracellular electrical resistance and decreased permeability to ions and larger solutes, which are associated with enhanced ultrastructural integrity of bTJs toward enhanced strand linearity. In tTJs in contrast, ultrastructure was unchanged and tricellulin minimized permeability to macromolecules but not to ions. This paradox is explained by properties of the tTJ central tube which is wide enough for passage of macromolecules, but too rare to contribute significantly to ion permeability. In conclusion, at low tricellulin expression the tTJ central tube forms a pathway for macromolecules. At higher expression, tricellulin forms a barrier in tTJs effective only for macromolecules and in bTJs for solutes of all sizes.

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Section: Tricellulin Reduces Btj Ion Permeability Without Change In Smentioning

confidence: 99%

Tricellulin Forms a Barrier to Macromolecules in Tricellular Tight Junctions without Affecting Ion Permeability

Krug

Amasheh

Richter

et al. 2009

MBoC

300

322

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“…In the confined microdroplet, both the favorable (negative) ion-ligand and unfavorable (positive) ligand-ligand interactions contribute and compete, in a nontrivial manner, to control selectivity (17). There are some similarities with Eisenman's classic concept of field-strength, in which structurally featureless binding sites are selective by virtue of the chemical type of ion-coordinating ligands (33). This view is also closely related to the model proposed to explain the selectivity of Ca 2þ channels in which the ion and the negatively charged carboxylate groups of the protein are allowed to dynamically fluctuate within a confined subvolume (34).…”

Section: Relative Freementioning

confidence: 99%

Two mechanisms of ion selectivity in protein binding sites

Noskov

Roux

2010

Proc. Natl. Acad. Sci. U.S.A.

165

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A theoretical framework is presented to clarify the molecular determinants of ion selectivity in protein binding sites. The relative free energy of a bound ion is expressed in terms of the main coordinating ligands coupled to an effective potential of mean force representing the influence of the rest of the protein. The latter is separated into two main contributions. The first includes all the forces keeping the ion and the coordinating ligands confined to a microscopic subvolume but does not prevent the ligands from adapting to a smaller or larger ion. The second regroups all the remaining forces that control the precise geometry of the coordinating ligands best adapted to a given ion. The theoretical framework makes it possible to delineate two important limiting cases. In the limit where the geometric forces are dominant (rigid binding site), ion selectivity is controlled by the ion-ligand interactions within the matching cavity size according to the familiar "snugfit" mechanism of host-guest chemistry. In the limit where the geometric forces are negligible, the ion and ligands behave as a "confined microdroplet" that is free to fluctuate and adapt to ions of different sizes. In this case, ion selectivity is set by the interplay between ion-ligand and ligand-ligand interactions and is controlled by the number and the chemical type of ion-coordinating ligands. The framework is illustrated by considering the ion-selective binding sites in the KcsA channel and the LeuT transporter.computations | free energy | ion coordination | KcsA | LeuT

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“…One approach to the problem has arisen from studies of the mechanism of ion selectivity in nonbiological systems, such as glasses of various composition (Eisenman, 1962(Eisenman, , 1967Eisenman and Conti, 1965). These systems have been well characterized since the nature of the moieties which mediate ion permeation is known.…”

Section: Introductionmentioning

confidence: 99%

Cation and anion sequences in dark-adapted Balanus photoreceptor.

Brown¹,

Saunders²

1977

The Journal of General Physiology

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A B S T R A C T Anionand cation permeabilities in dark-adapted Balanus photoreceptors were determined by comparing changes in the membrane potential in response to replacement of the dominant anion (Cl-) or cation (Na ÷) by test anions or cations in the superfusing solution. The anion permeability sequence obtained was PI > Pso~ > PBr > PCl > eisethionate > Pmethanesulfonate. Gluconate, glucuronate, and glutamate generally appeared more permeable and propionate less permeable than CI-. The alkali-metal cation permeability sequence obtained was PK > Pab > Pcs > PNa ~ PLi. This corresponds to Eisenman's sequence IV which is the same sequence that has been obtained for other classes of nerve cells in the resting state. The values obtained for the permeability ratios of the alkali-metal cations are considered to be minimal. The membrane conductance measured by passing inward current pulses in the different test cations followed the sequence, GK > GRb > Gcs > GNa > GIj. The conductance ratios obtained for a full substitution of the test cation agreed quite well with permeability ratios for all the alkali-metal cations except K + which was generally higher.

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Cation Selective Glass Electrodes and their Mode of Operation

Cited by 826 publications

References 38 publications

Tricellulin Forms a Barrier to Macromolecules in Tricellular Tight Junctions without Affecting Ion Permeability

Tricellulin Forms a Barrier to Macromolecules in Tricellular Tight Junctions without Affecting Ion Permeability

Two mechanisms of ion selectivity in protein binding sites

Cation and anion sequences in dark-adapted Balanus photoreceptor.

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