Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
Fast, triangular voltage clamp for recording and kinetic analysis of an ion transporter expressed in Xenopus oocytes.
Gradmann D
,
Boyd CM
.
???displayArticle.abstract???
We present a procedure for determination of 11 system parameters of an ion transporter expressed in Xenopus oocytes. The experiments consist of fast triangular voltage-clamp experiments in the presence and absence of external substrate. A four-state enzymatic cycle operating between an external and an internal section of electrodiffusion is used for analysis. The explicit example treats experiments with the fungal 2H+-NO3- symporter EnNRT, a member of the major superfamily transporters. The results comprise a density of approximately 150 fmol functional transporter molecules per oocyte, a gross charge number z(E) approximately -0.3 of the empty binding site of the enzyme, individual rate constants for reorientation of the empty and occupied binding site in the range of 5-500 s(-1), electrical access sections between bulk solutions and reaction cycle of approximately 3% inside and 15% outside, an increase of internal NO3- at the plasma membrane from approximately 0.5 to approximately 2 mM during exposure to external NO3-, and K(D) approximately 0.3 microM3 inside and K(D) approximately 3 microM3 outside in binding the triplicate substrate (2H+ +NO3-). The results compare well with the known structure of the lactose permease, another major superfamily transporter.
Abramson,
Structure and mechanism of the lactose permease of Escherichia coli.
2003, Pubmed
Abramson,
Structure and mechanism of the lactose permease of Escherichia coli.
2003,
Pubmed
Bernèche,
Energetics of ion conduction through the K+ channel.
2001,
Pubmed
Boyd,
Transinhibition and voltage-gating in a fungal nitrate transporter.
2003,
Pubmed
,
Xenbase
De Weer,
Voltage dependence of the apparent affinity for external Na(+) of the backward-running sodium pump.
2001,
Pubmed
Fohlmeister,
Gating current harmonics. IV. Dynamic properties of secondary activation kinetics in sodium channel gating.
1987,
Pubmed
Gradmann,
Electrophysiology of the marine diatom Coscinodiscus wailesii IV: types of non-linear current-voltage-time relationships recorded with single saw-tooth voltage-clamp experiments.
1999,
Pubmed
Gradmann,
Apparent charge of binding site in ion-translocating enzymes: kinetic impact.
2005,
Pubmed
Gradmann,
Three types of membrane excitations in the marine diatom Coscinodiscus wailesii.
2000,
Pubmed
Gradmann,
Current-voltage-time records of ion translocating enzymes.
2004,
Pubmed
Hansen,
Interpretation of current-voltage relationships for "active" ion transport systems: II. Nonsteady-state reaction kinetic analysis of class-I mechanisms with one slow time-constant.
1983,
Pubmed
Hansen,
Interpretation of current-voltage relationships for "active" ion transport systems: I. Steady-state reaction-kinetic analysis of class-I mechanisms.
1981,
Pubmed
Huang,
Structure and mechanism of the glycerol-3-phosphate transporter from Escherichia coli.
2003,
Pubmed
Kocic,
The effects of K+ channels modulators terikalant and glibenclamide on membrane potential changes induced by hypotonic challenge of guinea pig ventricular myocytes.
2004,
Pubmed
Lanyi,
Mechanism of proton transport in bacteriorhodopsin from crystallographic structures of the K, L, M1, M2, and M2' intermediates of the photocycle.
2003,
Pubmed
Läuger,
Kinetic properties of ion carriers and channels.
1980,
Pubmed
Morais-Cabral,
Energetic optimization of ion conduction rate by the K+ selectivity filter.
2001,
Pubmed
Neher,
Conductance fluctuations and ionic pores in membranes.
1977,
Pubmed
Rakowski,
Voltage dependence of Na/K pump current in Xenopus oocytes.
1988,
Pubmed
,
Xenbase
Rakowski,
Charge movement by the Na/K pump in Xenopus oocytes.
1993,
Pubmed
,
Xenbase
Sagar,
Access channel model for the voltage dependence of the forward-running Na+/K+ pump.
1994,
Pubmed
,
Xenbase
Schmitt,
An improved method for real-time monitoring of membrane capacitance in Xenopus laevis oocytes.
2002,
Pubmed
,
Xenbase
Solsona,
Regulation of exocytotic fusion by cell inflation.
1998,
Pubmed
Stühmer,
Electrophysiological recording from Xenopus oocytes.
1992,
Pubmed
,
Xenbase
Tittor,
Impedance of the electrogenic Cl(-) pump inAcetabularia: Electrical frequency entrainements, voltage-sensitivity, and reaction kinetic interpretation.
1983,
Pubmed
Unkles,
crnA encodes a nitrate transporter in Aspergillus nidulans.
1991,
Pubmed
Zagotta,
Shaker potassium channel gating. III: Evaluation of kinetic models for activation.
1994,
Pubmed
,
Xenbase
Zampighi,
A method for determining the unitary functional capacity of cloned channels and transporters expressed in Xenopus laevis oocytes.
1995,
Pubmed
,
Xenbase
Zei,
Voltage-dependent gating of single wild-type and S4 mutant KAT1 inward rectifier potassium channels.
1998,
Pubmed
,
Xenbase
Zhou,
A high affinity fungal nitrate carrier with two transport mechanisms.
2000,
Pubmed
,
Xenbase