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Biophys J. 1993 Nov;65(5):2089-96.

Conduction properties of the cloned Shaker K+ channel.

Author information

1
Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115.

Abstract

The conduction properties of the cloned Shaker K+ channel were studied using electrophysiological techniques. Single channel conductance increases in a sublinear manner with symmetric increases in K+ activity, reaching saturation by 0.6 M K+. The Shaker K+ channel is highly selective among monovalent cations; under bi-ionic conditions, its selectivity sequence is K+ > Rb+ > NH+4 > Cs+ > Na+, whereas, by relative conductance in symmetric solutions, it is K+ > NH+4 > Rb+ > Cs+. In Cs+ solutions, single channel currents were too small to be measured directly, so nonstationary fluctuation analysis was used to determine the unitary Cs+ conductance. The single channel conductance displays an anomalous molefraction effect in symmetric mixtures of K+ and NH+4, suggesting that the conducting pore is occupied by multiple ions simultaneously.

PMID:
8298038
PMCID:
PMC1225944
DOI:
10.1016/S0006-3495(93)81244-X
[Indexed for MEDLINE]
Free PMC Article

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