The open pore conformation of potassium channels.
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 K(+) channels, respectively, reveal how such gating transitions occur. Pore-lining 'inner' helices contain a 'gating hinge' that bends by approximately 30 degrees. 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 K(+) 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.
Jiang
Youxing
Y
Howard Hughes Medical Institute, Laboratory of Molecular Neurobiology and Biophysics, Rockefeller University, 1230 York Avenue, New York, New York 10021, USA.
Lee
Alice
A
Chen
Jiayun
J
Cadene
Martine
M
Chait
Brian T
BT
MacKinnon
Roderick
R
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D004553:Electric Conductivity; D015640:Ion Channel Gating; D008024:Ligands; D008564:Membrane Potentials; D017014:Methanobacterium / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015221:Potassium Channels / Q000737:chemistry* / Q000378:metabolism*; D024681:Potassium Channels, Calcium-Activated / Q000737:chemistry / Q000378:metabolism; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D021122:Protein Subunits; D016415:Sequence Alignment; D055672:Static Electricity; D013329:Structure-Activity Relationship
D001426:Bacterial Proteins; D008024:Ligands; D015221:Potassium Channels; D024681:Potassium Channels, Calcium-Activated; D021122:Protein Subunits; C107790:prokaryotic potassium channel