| Автор | Beckstein, Oliver |
| Автор | Sansom, Mark S P |
| Дата выпуска | 2006-06-01 |
| dc.description | The nicotinic acetylcholine receptor (nAChR) is the prototypic member of the ‘Cys-loop’ superfamily of ligand-gated ion channels which mediate synaptic neurotransmission, and whose other members include receptors for glycine, γ-aminobutyric acid and serotonin. Cryo-electron microscopy has yielded a three-dimensional structure of the nAChR in its closed state. However, the exact nature and location of the channel gate remains uncertain. Although the transmembrane pore is constricted close to its center, it is not completely occluded. Rather, the pore has a central hydrophobic zone of radius about 3 Å. Model calculations suggest that such a constriction may form a hydrophobic gate, preventing movement of ions through a channel. We present a detailed and quantitative simulation study of the hydrophobic gating model of the nicotinic receptor, in order to fully evaluate this hypothesis. We demonstrate that the hydrophobic constriction of the nAChR pore indeed forms a closed gate. Potential of mean force (PMF) calculations reveal that the constriction presents a barrier of height about 10 kT to the permeation of sodium ions, placing an upper bound on the closed channel conductance of 0.3 pS. Thus, a 3 Å radius hydrophobic pore can form a functional barrier to the permeation of a 1 Å radius Na<sup>+</sup> ion. Using a united-atom force field for the protein instead of an all-atom one retains the qualitative features but results in differing conductances, showing that the PMF is sensitive to the detailed molecular interactions. |
| Формат | application.pdf |
| Издатель | Institute of Physics Publishing |
| Копирайт | 2006 IOP Publishing Ltd |
| Название | A hydrophobic gate in an ion channel: the closed state of the nicotinic acetylcholine receptor |
| Тип | paper |
| DOI | 10.1088/1478-3975/3/2/007 |
| Electronic ISSN | 1478-3975 |
| Print ISSN | 1478-3967 |
| Журнал | Physical Biology |
| Том | 3 |
| Первая страница | 147 |
| Последняя страница | 159 |
| Аффилиация | Beckstein, Oliver; The Johns Hopkins University, School of Medicine, Department of Physiology, Biophysics 206, 725 N Wolfe St, Baltimore, MD 21205, USA; Structural Bioinformatics and Computational Biochemistry Unit, Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK |
| Аффилиация | Sansom, Mark S P; Structural Bioinformatics and Computational Biochemistry Unit, Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK |
| Выпуск | 2 |
