scholarly journals Function of Shaker potassium channels produced by cell-free translation upon injection into Xenopus oocytes

2013 ◽  
Vol 3 (1) ◽  
Author(s):  
Brian W. Jarecki ◽  
Shin-ichi Makino ◽  
Emily T. Beebe ◽  
Brian G. Fox ◽  
Baron Chanda
Keyword(s):  
Potassium Channels ◽  
Xenopus Oocytes ◽  
Free Translation ◽  
Shaker Potassium Channels

scholarly journals Function of Shaker Potassium Channels Produced by Cell-Free Translation Upon Injection into Xenopus Oocytes

2013 ◽  
Vol 104 (2) ◽  
pp. 197a
Author(s):  
Brian W. Jarecki ◽  
Shin-ichi Makino ◽  
Emily T. Beebe ◽  
Brian G. Fox ◽  
Baron Chanda
Keyword(s):  
Potassium Channels ◽  
Xenopus Oocytes ◽  
Free Translation ◽  
Shaker Potassium Channels

scholarly journals How Does the W434F Mutation Block Current in Shaker Potassium Channels?

1997 ◽  
Vol 109 (6) ◽  
pp. 779-789 ◽  
Author(s):  
Youshan Yang ◽  
Yangyang Yan ◽  
Fred J. Sigworth
Keyword(s):  
Potassium Channels ◽  
Potassium Current ◽  
Xenopus Oocytes ◽  
Single Channel ◽  
Ion Selectivity ◽  
Independent Component ◽  
Single Channel Recordings ◽  
Shaker Channels ◽  
Rapid Inactivation ◽  
Shaker Potassium Channels

The mutation W434F produces an apparently complete block of potassium current in Shaker channels expressed in Xenopus oocytes. Tandem tetrameric constructs containing one or two subunits with this mutation showed rapid inactivation, although the NH2-terminal inactivation domain was absent from these constructs. The inactivation showed a selective dependence on external cations and was slowed by external TEA; these properties are characteristic of C-type inactivation. Inactivation was, however, incompletely relieved by hyperpolarization, suggesting the presence of a voltage-independent component. The hybrid channels had near-normal conductance and ion selectivity. Single-channel recordings from patches containing many W434F channels showed occasional channel openings, consistent with open probabilities of 10−5 or less. We conclude that the W434F mutation produces a channel that is predominantly found in an inactivated state.

scholarly journals Ion Conduction through C-Type Inactivated Shaker Channels

1997 ◽  
Vol 110 (5) ◽  
pp. 539-550 ◽  
Author(s):  
John G. Starkus ◽  
Lioba Kuschel ◽  
Martin D. Rayner ◽  
Stefan H. Heinemann
Keyword(s):  
Potassium Channels ◽  
Xenopus Oocytes ◽  
Ion Selectivity ◽  
Complete Removal ◽  
Ion Conduction ◽  
Internal Solution ◽  
Shaker Channels ◽  
Na Ions ◽  
Shaker Potassium Channels ◽  
Inside Out

C-type inactivation of Shaker potassium channels involves entry into a state (or states) in which the inactivated channels appear nonconducting in physiological solutions. However, when Shaker channels, from which fast N-type inactivation has been removed by NH2-terminal deletions, are expressed in Xenopus oocytes and evaluated in inside-out patches, complete removal of K+ ions from the internal solution exposes conduction of Na+ and Li+ in C-type inactivated conformational states. The present paper uses this observation to investigate the properties of ion conduction through C-type inactivated channel states, and demonstrates that both activation and deactivation can occur in C-type states, although with slower than normal kinetics. Channels in the C-type states appear “inactivated” (i.e., nonconducting) in physiological solutions due to the summation of two separate effects: first, internal K+ ions prevent Na+ ions from permeating through the channel; second, C-type inactivation greatly reduces the permeability of K+ relative to the permeability of Na+, thus altering the ion selectivity of the channel.

scholarly journals Probing the Cavity of the Slow Inactivated Conformation of Shaker Potassium Channels

2007 ◽  
Vol 129 (5) ◽  
pp. 403-418 ◽  
Author(s):  
Gyorgy Panyi ◽  
Carol Deutsch
Keyword(s):  
Potassium Channels ◽  
Binding Site ◽  
Conformational Change ◽  
Marked Decrease ◽  
Selectivity Filter ◽  
Slow Inactivation ◽  
Voltage Gated ◽  
Activation Gate ◽  
Shaker Potassium Channels

Slow inactivation involves a local rearrangement of the outer mouth of voltage-gated potassium channels, but nothing is known regarding rearrangements in the cavity between the activation gate and the selectivity filter. We now report that the cavity undergoes a conformational change in the slow-inactivated state. This change is manifest as altered accessibility of residues facing the aqueous cavity and as a marked decrease in the affinity of tetraethylammonium for its internal binding site. These findings have implications for global alterations of the channel during slow inactivation and putative coupling between activation and slow-inactivation gates.

Effects of antiarrhythmic drugs on cloned cardiac voltage-gated potassium channels expressed in Xenopus oocytes

2000 ◽  
Vol 362 (1) ◽  
pp. 22-31 ◽  
Author(s):  
Sascha Rolf ◽  
Wilhelm Haverkamp ◽  
Martin Borggrefe ◽  
Ulrich Mußhoff ◽  
Lars Eckardt ◽  
...  
Keyword(s):  
Potassium Channels ◽  
Xenopus Oocytes ◽  
Antiarrhythmic Drugs ◽  
Voltage Gated

Mechanisms of the inhibition of Shaker potassium channels by protons

2003 ◽  
Vol 447 (1) ◽  
pp. 44-54 ◽  
Author(s):  
John G. Starkus ◽  
Zoltan Varga ◽  
Roland Sch�nherr ◽  
Stefan H. Heinemann
Keyword(s):  
Potassium Channels ◽  
Shaker Potassium Channels
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