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  Dimensions of the narrow portion of a recombinant NMDA receptor channel

Villarroel, A., Burnashev, N., & Sakmann, B. (1995). Dimensions of the narrow portion of a recombinant NMDA receptor channel. Biophysical Journal, 68(3), 866-875. doi:10.1016/S0006-3495(95)80263-8.

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Item Permalink: http://hdl.handle.net/11858/00-001M-0000-002B-60D2-C Version Permalink: http://hdl.handle.net/11858/00-001M-0000-002B-60D3-A
Genre: Journal Article
Alternative Title : Dimensions of the narrow portion of a recombinant NMDA receptor channel

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BiophysJ_68_1995_866.pdf (Any fulltext), 9MB
 
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Villarroel, Alfredo1, Author              
Burnashev, Nail1, Author              
Sakmann, Bert1, Author              
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1Department of Cell Physiology, Max Planck Institute for Medical Research, Max Planck Society, ou_1497701              

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 Abstract: Glutamate-activated single-channel and ensemble currents were recorded from Xenopus laevis oocytes and HEK 293 cells expressing a recombinant NMDA receptor, assembled from NR1 and NR2A subunits. Cesium was the main charge carrier, and organic cations were used to determine the presence of vestibules of this channel and to estimate its pore diameter. The large organic cations tris-(hydroxymethyl)-aminomethane (Tris), N-methyl-glucamine (NMG), arginine (NMG), arginine (Arg), choline, and tetramethylammonium (TMA), when added in millimolar concentrations to the extracellular or cytoplasmic side, produced a voltage-dependent blockade of single-channel Cs+ currents. These molecules behaved as impermeant ions that only partially traverse the channel from either side. The smaller cations trimethylammonium (TriMA) and dimethylammonium (DMA) produced a small and nearly voltage-independent reduction in current amplitude, suggesting that they are permeant. In biionic experiments with Cs+ as the reference ion, the large blocking cations NMG, Arg, Tris, TMA, choline, hexamethonium (Hme), triethylammonium (TriEA), and tetraethylammonium (TEA) showed no measurable permeability. TriMA and smaller ammonium derivatives were permeant. Both the permeability and single-channel conductance of organic cations, relative to Cs+, decreased as the ion size increased. The results suggest that the NMDA receptor has extracellular and cytoplasmic mouths that can accommodate large cations up to 7.3 A in mean diameter. The narrow portion of the pore is estimated to have a mean diameter of 5.5 A.

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Language(s): eng - English
 Dates: 1994-12-131994-06-171994-12-131995-03-01
 Publication Status: Published in print
 Pages: 10
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 Table of Contents: -
 Rev. Type: Peer
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Title: Biophysical Journal
  Other : Biophys. J.
Source Genre: Journal
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Publ. Info: Cambridge, Mass. : Cell Press
Pages: - Volume / Issue: 68 (3) Sequence Number: - Start / End Page: 866 - 875 Identifier: Other: 0006-3495
CoNE: https://pure.mpg.de/cone/journals/resource/954925385117