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The open pore conformation of potassium channels
 

Summary: The open pore conformation of
potassium channels
Youxing Jiang, Alice Lee, Jiayun Chen, Martine Cadene, Brian T. Chait & Roderick MacKinnon
Howard Hughes Medical Institute, Laboratory of Molecular Neurobiology and Biophysics and Laboratory of Mass Spectrometry and Gaseous Ion Chemistry,
Rockefeller University, 1230 York Avenue, New York, New York 10021, USA
...........................................................................................................................................................................................................................
Living cells regulate the activity of their ion channels through a process known as gating. To open the pore, protein conformational
changes must occur within a channel's membrane-spanning ion pathway. KcsA and MthK, closed and opened K1
channels,
respectively, reveal how such gating transitions occur. Pore-lining `inner' helices contain a `gating hinge' that bends by
approximately 308. In a straight conformation four inner helices form a bundle, closing the pore near its intracellular surface. In a
bent configuration the inner helices splay open creating a wide (12 A ) entryway. Amino-acid sequence conservation suggests a
common structural basis for gating in a wide range of K1
channels, both ligand- and voltage-gated. The open conformation favours
high conduction by compressing the membrane field to the selectivity filter, and also permits large organic cations and inactivation
peptides to enter the pore from the intracellular solution.
Potassium and other ion channels are allosteric proteins that switch
between closed and opened conformations in response to an
external stimulus in a process known as gating. Depending on the
channel type, the gating stimulus can be the binding of a ligand, the

  

Source: Akabas, Myles - Department of Physiology and Biophysics, Albert Einstein College of Medicine, Yeshiva University
Chait, Brian T. - Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, Rockefeller University
Huettner, James E. - Department of Cell Biology and Physiology, Washington University in St. Louis

 

Collections: Biology and Medicine