Evaluation and Comparison of Ion Permeation and Agonist Selectivities for N-Methyl--Aspartate Receptor Channels with Different Subunit Compositions in Bilayer Lipid Membranes Based on Integrated Single-Channel Currents

2000 ◽  
Vol 283 (2) ◽  
pp. 258-265 ◽  
Author(s):  
Ayumi Hirano ◽  
Masaki Wakabayashi ◽  
Masao Sugawara ◽  
Shigeo Uchino ◽  
Sadayo Nakajima-Iijima
Keyword(s):  
Lipid Membranes ◽  
Single Channel ◽  
Bilayer Lipid Membranes ◽  
Ion Permeation ◽  
Bilayer Lipid ◽  
Aspartate Receptor ◽  
Methyl Aspartate ◽  
Single Channel Currents ◽  
Channel Currents

scholarly journals Desensitization of Mouse Nicotinic Acetylcholine Receptor Channels

1998 ◽  
Vol 112 (2) ◽  
pp. 181-197 ◽  
Author(s):  
Anthony Auerbach ◽  
Gustav Akk
Keyword(s):  
Acetylcholine Receptor ◽  
Rate Constant ◽  
Binding Sites ◽  
Single Channel ◽  
Ion Permeation ◽  
Activation Gate ◽  
The Status ◽  
Single Channel Currents ◽  
Cyclic Models ◽  
Channel Currents

The rate constants of acetylcholine receptor channels (AChR) desensitization and recovery were estimated from the durations and frequencies of clusters of single-channel currents. Diliganded-open AChR desensitize much faster than either unliganded- or diliganded-closed AChR, which indicates that the desensitization rate constant depends on the status of the activation gate rather than the occupancy of the transmitter binding sites. The desensitization rate constant does not change with the nature of the agonist, the membrane potential, the species of permeant cation, channel block by ACh, the subunit composition (ε or γ), or several mutations that are near the transmitter binding sites. The results are discussed in terms of cyclic models of AChR activation, desensitization, and recovery. In particular, a mechanism by which activation and desensitization are mediated by two distinct, but interrelated, gates in the ion permeation pathway is proposed.

scholarly journals Stoichiometry of Recombinant N-Methyl-d-Aspartate Receptor Channels Inferred from Single-channel Current Patterns

1997 ◽  
Vol 110 (5) ◽  
pp. 485-502 ◽  
Author(s):  
Louis S. Premkumar ◽  
Anthony Auerbach
Keyword(s):  
Single Channel ◽  
Wild Type ◽  
Current Pattern ◽  
Channel Current ◽  
Single Channel Current ◽  
Aspartate Receptor ◽  
Single Channel Currents ◽  
Nr2 Subunits ◽  
Channel Currents ◽  
Straightforward Interpretation

Single-channel currents were recorded from mouse NR1-NR2B (ζ-ε2) receptors containing mixtures of wild-type and mutant subunits expressed in Xenopus oocytes. Mutant subunits had an asparagine-to-glutamine (N-to-Q) mutation at the N0 site of the M2 segment (NR1:598, NR2B:589). Receptors with pure N or Q NR1 and NR2 subunits generated single-channel currents with distinctive current patterns. Based on main and sublevel amplitudes, occupancy probabilities, and lifetimes, four patterns of current were identified, corresponding to receptors with the following subunit compositions (NR1/NR2): N/N, N/Q, Q/N, and Q/Q. Only one current pattern was apparent for each composition. When a mixture of N and Q NR2 subunits was coexpressed with pure mutant NR1 subunits, three single-channel current patterns were apparent. One pattern was the same as Q/Q receptors and another was the same as Q/N receptors. The third, novel pattern presumably arose from hybrid receptors having both N and Q NR2 subunits. When a mixture of N and Q NR1 subunits was coexpressed with pure mutant NR2 subunits, six single-channel current patterns were apparent. One pattern was the same as Q/Q receptors and another was the same as N/Q receptors. The four novel patterns presumably arose from hybrid receptors having both N and Q NR1 subunits. The relative frequency of NR1 hybrid receptor current patterns depended on the relative amounts of Q and N subunits that were injected into the oocytes. The number of hybrid receptor patterns suggests that there are two NR2 subunits per receptor and is consistent with either three or five NR1 subunits per receptor, depending on whether or not the order of mutant and wild-type subunits influences the current pattern. When considered in relation to other studies, the most straightforward interpretation of the results is that N-methyl-d-aspartate receptors are pentamers composed of three NR1 and two NR2 subunits.

Modeling Ion Transport in Tethered Bilayer Lipid Membranes. 1. Passive Ion Permeation

2008 ◽  
Vol 112 (34) ◽  
pp. 10475-10482 ◽  
Author(s):  
Joseph W. F. Robertson ◽  
Marcel G. Friedrich ◽  
Asmorom Kibrom ◽  
Wolfgang Knoll ◽  
Renate L. C. Naumann ◽  
...  
Keyword(s):  
Ion Transport ◽  
Lipid Membranes ◽  
Bilayer Lipid Membranes ◽  
Ion Permeation ◽  
Bilayer Lipid

Analysis of Single Channel Currents with a Microprocessor Based Device

1987 ◽  
Vol 42 (3) ◽  
pp. 173-177
Author(s):  
W. Schreibmayer ◽  
E. Hofer ◽  
P. Wolf ◽  
A. Lueger ◽  
H. A. Tritthart
Keyword(s):  
Lipid Membranes ◽  
Single Channel ◽  
Histogram Analysis ◽  
Mass Storage ◽  
Constant Frequency ◽  
Storage Oscilloscope ◽  
Black Lipid Membranes ◽  
Amplitude Histogram ◽  
Single Channel Currents ◽  
Channel Currents

Data evaluation of single channel currents obtained from artificial black lipid membranes and with the patch clamp method is an important part of every single channel study, but it is a time consuming part often exceeding the time for experimentation and recording by far. We describe here a microprocessor based device, which allows the experimentator to analyse in a simple way the distribution of current levels in a single channel trace (amplitude-histogram analysis of single channel currents) either online, or offline. Current levels are sampled at a constant frequency of 6 kHz and the relative frequencies of occurrence of these current levels are displayed as a histogram on the screen of an analog or digital storage oscilloscope. The data reducing algorithm of this analyser eliminates the requirement of large amounts of mass storage that normally is needed for digital amplitude-histogram analysis of single channel recordings. Examples of evaluation for both a voltage operated cation-channel and a blockage of a potas­sium channel by tetraethylammoniumchloride (TEA) are given.

scholarly journals Analysis of Ion Transport through a Single Channel of Gramicidin A in Bilayer Lipid Membranes

2016 ◽  
Vol 32 (2) ◽  
pp. 189-192 ◽  
Author(s):  
Shintaro KUBOTA ◽  
Osamu SHIRAI ◽  
Yuki KITAZUMI ◽  
Kenji KANO
Keyword(s):  
Ion Transport ◽  
Lipid Membranes ◽  
Single Channel ◽  
Gramicidin A ◽  
Bilayer Lipid Membranes ◽  
Bilayer Lipid
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