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The conduction pore of a cardiac potassium channel

The conduction pore of a cardiac potassium channel Ion channels form transmembrane water-filled pores that allow ions to cross membranes in a rapid and selective fashion. The amino acid residues that line these pores have been sought to reveal the mechanisms of ion conduction and selectivity 1,2,3,4,5,6,7 . The pore (P) loop 8 is a stretch of residues that influences single-channel-current amplitude, selectivity among ions and open-channel blockade 2 , 3 , 5 and is conserved in potassium-channel subunits previously recognized to contribute to pore formation 5 , 9 . To date, potassium-channel pores have been shown to form by symmetrical alignment of four P loops around a central conduction pathway 10,11,12 . Here we show that the selectivity-determining pore region of the voltage-gated potassium channel of human heart through which the I Ks current passes includes the transmembrane segment of the non-P-loop protein minK. Two adjacent residues in this segment of minK are exposed in the pore on either side of a short barrier that restricts the movement of sodium, cadmium and zinc ions across the membrane. Thus, potassium-selective pores are not restricted to P loops or a strict P-loop geometry. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Nature Springer Journals

The conduction pore of a cardiac potassium channel

Tai, Kwok-Keung; Goldstein, Steve A. N.
Nature , Volume 391 (6667) – Feb 5, 1998
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References (31)

Publisher
Springer Journals
Copyright
Copyright © 1998 by Macmillan Magazines Ltd.
Subject
Science, Humanities and Social Sciences, multidisciplinary; Science, Humanities and Social Sciences, multidisciplinary; Science, multidisciplinary
ISSN
0028-0836
eISSN
1476-4687
DOI
10.1038/35416
Publisher site
See Article on Publisher Site

Abstract

Ion channels form transmembrane water-filled pores that allow ions to cross membranes in a rapid and selective fashion. The amino acid residues that line these pores have been sought to reveal the mechanisms of ion conduction and selectivity 1,2,3,4,5,6,7 . The pore (P) loop 8 is a stretch of residues that influences single-channel-current amplitude, selectivity among ions and open-channel blockade 2 , 3 , 5 and is conserved in potassium-channel subunits previously recognized to contribute to pore formation 5 , 9 . To date, potassium-channel pores have been shown to form by symmetrical alignment of four P loops around a central conduction pathway 10,11,12 . Here we show that the selectivity-determining pore region of the voltage-gated potassium channel of human heart through which the I Ks current passes includes the transmembrane segment of the non-P-loop protein minK. Two adjacent residues in this segment of minK are exposed in the pore on either side of a short barrier that restricts the movement of sodium, cadmium and zinc ions across the membrane. Thus, potassium-selective pores are not restricted to P loops or a strict P-loop geometry.

Journal

Nature – Springer Journals

Published: Feb 5, 1998

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