Two Stable, Conducting Conformations of the Selectivity Filter in Shaker K+ Channels
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چکیده
منابع مشابه
Two Stable, Conducting Conformations of the Selectivity Filter in Shaker K+ Channels
We have examined the voltage dependence of external TEA block of Shaker K(+) channels over a range of internal K(+) concentrations from 2 to 135 mM. We found that the concentration dependence of external TEA block in low internal K(+) solutions could not be described by a single TEA binding affinity. The deviation from a single TEA binding isotherm was increased at more depolarized membrane vol...
متن کاملExternal TEA Block of Shaker K+ Channels Is Coupled to the Movement of K+ Ions within the Selectivity Filter
Recent molecular dynamic simulations and electrostatic calculations suggested that the external TEA binding site in K+ channels is outside the membrane electric field. However, it has been known for some time that external TEA block of Shaker K+ channels is voltage dependent. To reconcile these two results, we reexamined the voltage dependence of block of Shaker K+ channels by external TEA. We ...
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Membrane voltage controls the passage of ions through voltage-gated K (K(v)) channels, and many studies have demonstrated that this is accomplished by a physical gate located at the cytoplasmic end of the pore. Critical to this determination were the findings that quaternary ammonium ions and certain peptides have access to their internal pore-blocking sites only when the channel gates are open...
متن کاملBinding Site in Shaker K Channels
We have examined the interaction between TEA and K 1 ions in the pore of Shaker potassium channels. We found that the ability of external TEA to antagonize block of Shaker channels by internal TEA depended on internal K 1 ions. In contrast, this antagonism was independent of external K 1 concentrations between 0.2 and 40 mM. The external TEA antagonism of internal TEA block increased linearly w...
متن کاملPreferential binding of K+ ions in the selectivity filter at equilibrium explains high selectivity of K+ channels
K(+) channels exhibit strong selectivity for K(+) ions over Na(+) ions based on electrophysiology experiments that measure ions competing for passage through the channel. During this conduction process, multiple ions interact within the region of the channel called the selectivity filter. Ion selectivity may arise from an equilibrium preference for K(+) ions within the selectivity filter or fro...
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ژورنال
عنوان ژورنال: Journal of General Physiology
سال: 2005
ISSN: 1540-7748,0022-1295
DOI: 10.1085/jgp.200509251