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Palma A
,
Li L
,
Chen XJ
,
Pappone P
,
McNamee M
.
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We have examined the effects of changing extracellular pH on the function of nicotinic acetylcholine receptors from Torpedo californica using ion flux and electrophysiological methods. Agonist-induced cation efflux from vesicles containing purified, reconstituted receptors showed a monotonic dependence on external hydrogen ion concentration with maximal fluxes at alkaline pH and no agonist-induced efflux at pH's less than approximately 5. A similar pH dependence was measured for the peak agonist-activated membrane currents measured in microelectrode voltage-clamped Xenopus oocytes induced to express Torpedo receptor through mRNA injection. Half-maximal inhibition occurred at a similar pH in both systems, in the range of pH 6.5-7.0. Single-channel currents from Torpedo ACh receptors measured in patch-clamp recordings were also reduced in amplitude at acid pH with an apparent pKa for block of less than 5. Measurements of channel kinetics had a more complicated dependence on pH. The mean channel open time determined from patch-clamp measurements was maximal at neutral pH and decreased at both acid and alkaline pH's. Thus, both channel permeability properties and channel gating properties are affected by the extracellular pH.
Adams,
The permeability of endplate channels to monovalent and divalent metal cations.
1980, Pubmed
Adams,
The permeability of endplate channels to monovalent and divalent metal cations.
1980,
Pubmed
Bezanilla,
A high capacity data recording device based on a digital audio processor and a video cassette recorder.
1985,
Pubmed
Bhushan,
Differential scanning calorimetry and Fourier transform infrared analysis of lipid-protein interactions involving the nicotinic acetylcholine receptor.
1990,
Pubmed
Dani,
Open channel structure and ion binding sites of the nicotinic acetylcholine receptor channel.
1989,
Pubmed
Dani,
Monovalent and divalent cation permeation in acetylcholine receptor channels. Ion transport related to structure.
1987,
Pubmed
Dwyer,
The permeability of the endplate channel to organic cations in frog muscle.
1980,
Pubmed
Fong,
Correlation between acetylcholine receptor function and structural properties of membranes.
1986,
Pubmed
Huang,
Selectivity of cations and nonelectrolytes for acetylcholine-activated channels in cultured muscle cells.
1978,
Pubmed
Imoto,
Location of a delta-subunit region determining ion transport through the acetylcholine receptor channel.
,
Pubmed
,
Xenbase
Imoto,
Rings of negatively charged amino acids determine the acetylcholine receptor channel conductance.
1988,
Pubmed
,
Xenbase
Landau,
pH dependence of the acetylcholine receptor channel: a species variation.
1981,
Pubmed
Lewis,
Ion-concentration dependence of the reversal potential and the single channel conductance of ion channels at the frog neuromuscular junction.
1979,
Pubmed
Methfessel,
Patch clamp measurements on Xenopus laevis oocytes: currents through endogenous channels and implanted acetylcholine receptor and sodium channels.
1986,
Pubmed
,
Xenbase
Pappone,
Modifications of single acetylcholine-activated channels in BC3H-1 cells. Effects of trimethyloxonium and pH.
1990,
Pubmed
Pradier,
Use of chemical modifications and site-directed mutagenesis to probe the functional role of thiol groups on the gamma subunit of Torpedo californica acetylcholine receptor.
1989,
Pubmed
,
Xenbase
Toyoshima,
Ion channel of acetylcholine receptor reconstructed from images of postsynaptic membranes.
1988,
Pubmed
