The ligand-sensitive gate of a potassium channel lies close to the selectivity filter.

Journal article

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.

Authors: Proks, P; Antcliff, J; Ashcroft, F

• Journal: EMBO reports
• Volume: 4
• Issue: 1
• Pages: 70-75
• Publication date: 2003-01-01
• DOI: 10.1038/sj.embor.embor708
• EISSN: 1469-3178
• ISSN: 1469-221X
• Language: English
• Keywords: Protein Conformation; Adenosine Triphosphate; Binding Sites; Oocytes; Cations, Divalent; Recombinant Proteins; Mice; Potassium; Protein Structure, Tertiary; Mutation, Missense; Models, Biological; Cadmium; Ion Channel Gating; Barium; Molecular Weight; Female; Xenopus laevis; Point Mutation; Animals; Ion Transport; Potassium Channels, Inwardly Rectifying; Ligands; Silver; Amino Acid Substitution