scholarly journals Ion permeation in potassium ion channels

2020 ◽  
Vol 76 (4) ◽  
pp. 326-331 ◽  
Author(s):  
Leighton Coates

The study of ion channels dates back to the 1950s and the groundbreaking electrophysiology work of Hodgin and Huxley, who used giant squid axons to probe how action potentials in neurons were initiated and propagated. More recently, several experiments using different structural biology techniques and approaches have been conducted to try to understand how potassium ions permeate through the selectivity filter of potassium ion channels. Two mechanisms of permeation have been proposed, and each of the two mechanisms is supported by different experiments. The key structural biology experiments conducted so far to try to understand how ion permeation takes place in potassium ion channels are reviewed and discussed. Protein crystallography has made, and continues to make, key contributions in this field, often through the use of anomalous scattering. Other structural biology techniques used to study the contents of the selectivity filter include solid-state nuclear magnetic resonance and two-dimensional infrared spectroscopy, both of which make clever use of isotopic labeling techniques, while molecular-dynamics simulations of ion flow through the selectivity filter have been enabled by the growing number of potassium ion channel structures deposited in the Protein Data Bank.

2017 ◽  
Vol 129 (41) ◽  
pp. 12842-12845 ◽  
Author(s):  
Chao Lang ◽  
Xiaoli Deng ◽  
Feihu Yang ◽  
Bing Yang ◽  
Wei Wang ◽  
...  

1998 ◽  
Vol 26 (4) ◽  
pp. 188-199
Author(s):  
E Kyriacou

The study of molecular transport across gall-bladder epithelium may contribute to our understanding of the pathophysiology of gall-bladder disease. The aim of this study was to reconstitute and characterize single potassium ion channels in bovine gall-bladder epithelial mucosa – both apical and basolateral aspects. Standard subcellular fractionation techniques were used to form either apical or basolateral closed-membrane vesicles from the mucosal epithelium of fresh gall bladders from healthy young adult cattle. Vesicular ion channels were incorporated into voltage-clamped planar lipid bilayers under known ionic conditions and their conductances, reversal potentials, and voltages were characterized. Low-conductance voltage-insensitive apical membrane vesicle channels of at least four conductance levels were found (mean ± SD): 12 ± 4 pS, n = 10; 40 ± 12 pS, n = 4; 273 ± 31 pS, n = 3; and 151 ± 24 pS, n = 5. Conductances of potassium ion channels in basolateral membrane vesicles were in the range 9–450 pS, and these channels included high-conductance calcium-activated potassium-ion channels ‘K(Ca)’ which were voltage- and calcium-dependent.


Author(s):  
M. Kocmalova ◽  
M. Oravec ◽  
M. Adamkov ◽  
V. Sadlonova ◽  
I. Kazimierova ◽  
...  

2021 ◽  
pp. 507-545
Author(s):  
Janna Bednenko ◽  
Paul Colussi ◽  
Sunyia Hussain ◽  
Yihui Zhang ◽  
Theodore Clark

Author(s):  
Patricia S. Langan ◽  
Venu Gopal Vandavasi ◽  
Brendan Sullivan ◽  
Joel Harp ◽  
Kevin Weiss ◽  
...  

The mechanism by which potassium ions are transported through ion channels is currently being investigated by several groups using many different techniques. Clarification of the location of water molecules during transport is central to understanding how these integral membrane proteins function. Neutrons have a unique sensitivity to both hydrogen and potassium, rendering neutron crystallography capable of distinguishing waters from K+ ions. Here, the collection of a complete neutron data set from a potassium ion channel to a resolution of 3.55 Å using the Macromolecular Neutron Diffractometer (MaNDi) is reported. A room-temperature X-ray data set was also collected from the same crystal to a resolution of 2.50 Å. Upon further refinement, these results will help to further clarify the ion/water population within the selectivity filter of potassium ion channels.


1990 ◽  
Vol 79 (4) ◽  
pp. 705-711 ◽  
Author(s):  
Friedrich-Wilhelm Bentrup

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