Putative resolution of the EEEE selectivity paradox in L-type Ca2+ and bacterial Na+ biological ion channels

Kaufman, Igor Kh and Luchinsky, Dmitrii Georgievich and Gibby, William A. T. and McClintock, Peter Vaughan Elsmere and Eisenberg, R. S. (2016) Putative resolution of the EEEE selectivity paradox in L-type Ca2+ and bacterial Na+ biological ion channels. Journal of Statistical Mechanics: Theory and Experiment, 2016: 054027. ISSN 1742-5468

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The highly selective permeation of ions through biological ion channels can be described and explained in terms of fluctuational dynamics under the influence of powerful electrostatic forces. Hence valence selectivity, e.g. between Ca2+ and Na+ in calcium and sodium channels, can be described in terms of ionic Coulomb blockade, which gives rise to distinct conduction bands and stop-bands as the fixed negative charge Qf at the selectivity filter of the channel is varied. This picture accounts successfully for a wide range of conduction phenomena in a diversity of ion channels. A disturbing anomaly, however, is that what appears to be the same electrostatic charge and structure (the so-called EEEE motif) seems to select Na+ conduction in bacterial channels but Ca2+ conduction in mammalian channels. As a possible resolution of this paradox it is hypothesised that an additional charged protein residue on the permeation path of the mammalian channel increases |Qf | by e, thereby altering the selectivity from Na+ to Ca2+. Experiments are proposed that will enable the hypothesis to be tested.

Item Type:
Journal Article
Journal or Publication Title:
Journal of Statistical Mechanics: Theory and Experiment
Uncontrolled Keywords:
?? biological ion channelscoulomb blockadestochastic dynamicseeee paradoxbrownian motionstochastic processes (theory)dynamics (theory)diffusionstatistical and nonlinear physicsstatistics and probabilitystatistics, probability and uncertainty ??
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Deposited On:
10 Nov 2015 16:24
Last Modified:
16 Jul 2024 23:46