ATR-FTIR Spectroscopy Revealing the Different Vibrational Modes of the Selectivity Filter Interacting with K+ and Na+ in the Open and Collapsed Conformations of the KcsA Potassium Channel

2012 ◽  
Vol 3 (24) ◽  
pp. 3806-3810 ◽  
Author(s):  
Yuji Furutani ◽  
Hirofumi Shimizu ◽  
Yusuke Asai ◽  
Tetsuya Fukuda ◽  
Shigetoshi Oiki ◽  
...  
Keyword(s):  
Potassium Channel ◽  
Ftir Spectroscopy ◽  
Selectivity Filter ◽  
Vibrational Modes ◽  
Kcsa Potassium Channel

Probing Ion Binding in the Selectivity Filter of the KcsA Potassium Channel

2019 ◽  
Vol 141 (18) ◽  
pp. 7391-7398 ◽  
Author(s):  
Cédric Eichmann ◽  
Lukas Frey ◽  
Innokentiy Maslennikov ◽  
Roland Riek
Keyword(s):  
Potassium Channel ◽  
Selectivity Filter ◽  
Ion Binding ◽  
Kcsa Potassium Channel

scholarly journals Conductance selectivity of Na+ across the K+ channel via Na+ trapped in a tortuous trajectory

2021 ◽  
Vol 118 (12) ◽  
pp. e2017168118
Author(s):  
Kenichiro Mita ◽  
Takashi Sumikama ◽  
Masayuki Iwamoto ◽  
Yuka Matsuki ◽  
Kenji Shigemi ◽  
...  
Keyword(s):  
Potassium Channel ◽  
Single Channel ◽  
Ion Selectivity ◽  
Carbonyl Oxygen ◽  
Selectivity Filter ◽  
K Channel ◽  
Selectivity Ratio ◽  
Channel Current ◽  
Dynamics Simulations ◽  
Kcsa Potassium Channel

Ion selectivity of the potassium channel is crucial for regulating electrical activity in living cells; however, the mechanism underlying the potassium channel selectivity that favors large K+ over small Na+ remains unclear. Generally, Na+ is not completely excluded from permeation through potassium channels. Herein, the distinct nature of Na+ conduction through the prototypical KcsA potassium channel was examined. Single-channel current recordings revealed that, at a high Na+ concentration (200 mM), the channel was blocked by Na+, and this blocking was relieved at high membrane potentials, suggesting the passage of Na+ across the channel. At a 2,000 mM Na+ concentration, single-channel Na+ conductance was measured as one-eightieth of the K+ conductance, indicating that the selectivity filter allows substantial conduit of Na+. Molecular dynamics simulations revealed unprecedented atomic trajectories of Na+ permeation. In the selectivity filter having a series of carbonyl oxygen rings, a smaller Na+ was distributed off-center in eight carbonyl oxygen-coordinated sites as well as on-center in four carbonyl oxygen-coordinated sites. This amphipathic nature of Na+ coordination yielded a continuous but tortuous path along the filter. Trapping of Na+ in many deep free energy wells in the filter caused slow elution. Conversely, K+ is conducted via a straight path, and as the number of occupied K+ ions increased to three, the concerted conduction was accelerated dramatically, generating the conductance selectivity ratio of up to 80. The selectivity filter allows accommodation of different ion species, but the ion coordination and interactions between ions render contrast conduction rates, constituting the potassium channel conductance selectivity.

Sodium ions do not stabilize the selectivity filter of a potassium channel

2021 ◽  
pp. 167091
Author(s):  
Kitty Hendriks ◽  
Carl Öster ◽  
Chaowei Shi ◽  
Han Sun ◽  
Adam Lange
Keyword(s):  
Potassium Channel ◽  
Selectivity Filter ◽  
Sodium Ions

scholarly journals Structural and Functional Consequences of an Amide-to-Ester Substitution in the Selectivity Filter of a Potassium Channel

2006 ◽  
Vol 128 (35) ◽  
pp. 11591-11599 ◽  
Author(s):  
Francis I. Valiyaveetil ◽  
Matthew Sekedat ◽  
Roderick MacKinnon ◽  
Tom W. Muir
Keyword(s):  
Potassium Channel ◽  
Selectivity Filter ◽  
Functional Consequences
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