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The ligand‐sensitive gate of a potassium channel lies close to the selectivity filter
Author(s) -
Proks Peter,
Antcliff Jennifer F,
Ashcroft Frances M
Publication year - 2003
Publication title -
embo reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.584
H-Index - 184
eISSN - 1469-3178
pISSN - 1469-221X
DOI - 10.1038/sj.embor.embor708
Subject(s) - selectivity , potassium channel , ligand (biochemistry) , chemistry , biophysics , potassium , membrane , filter (signal processing) , ligand gated ion channel , ion channel , biology , receptor , biochemistry , electrical engineering , organic chemistry , catalysis , engineering
Potassium channels selectively conduct K + ions across cell membranes and have key roles in cell excitability. Their opening and closing can be spontaneous or controlled by membrane voltage or ligand binding. We used Ba 2+ as a probe to determine the location of the ligand‐sensitive gate in an inwardly rectifying K + channel (Kir6.2). To a K + channel, Ba 2+ and K + are of similar sizes, but Ba 2+ blocks the pore by binding within the selectivity filter. We found that internal Ba 2+ could still access its binding site when the channel was shut, which indicates that the ligand‐sensitive gate lies above the Ba 2+ ‐block site, and thus within or above the selectivity filter. This is in marked contrast to the voltage‐dependent gate of K V channels, which is located at the intracellular mouth of the pore.