Functional reconstitution of the purified brain sodium channel in planar lipid bilayers.
- 1 January 1985
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 82 (1) , 240-244
- https://doi.org/10.1073/pnas.82.1.240
Abstract
The ion conduction and voltage dependence of sodium channels purified from rat brain were investigated in planar lipid bilayers in the presence of batrachotoxin. Single channel currents are clearly resolved. Channel opening is voltage dependent and favored by depolarization. The voltage at which the channel is open 50% of the time is -91 .+-. 17 mV (SD, n = 22) and the apparent gating charge is .apprxeq. 4. Tetrodotoxin reversibly blocks the ionic current through the sodium channels. The Ki for the tetrodotoxin blocks is 8.3 mM at -50 mV and is voltage dependent with the Ki increasing e-fold for depolarizations of 43 mV. The single channel conductance, .gamma., is ohmic. At 0.5 M salt concentrations .gamma. = 25 pS for Na+, 3.5 pS for K+ and 1.2 pS for Rb+. The purified brain sodium channel, which consists of 3 polypeptide subunits: .alpha. (MW .apprxeq. 260,000), .beta.1 (MW .apprxeq. 39,000) and .beta.2 (MW .apprxeq. 37,000), exhibits the same voltage dependence, neurotoxin sensitivity and ionic selectivity associated with native Na channels.This publication has 30 references indexed in Scilit:
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