ArticleThe Journal of general physiology1999
Localization of the K+ lock-In and the Ba2+ binding sites in a voltage-gated calcium-modulated channel. Implications for survival of K+ permeability.
Article in The Journal of general physiology, 1999. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 32 papers.
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Who cites it
32 citing papers in PubMed, 56 citations in OpenAlex.
- Mutation in pore-helix modulates interplay between filter gate and Ba2+ block in a Kcv channel pore.The Journal of general physiology · 2024Article
- Gating kinetics and pharmacological properties of small-conductance CaBiophysical journal · 2023Article
- Closed state-coupled C-type inactivation in BK channels.Proceedings of the National Academy of Sciences of the United States of America · 2016Article
- The conserved potassium channel filter can have distinct ion binding profiles: structural analysis of rubidium, cesium, and barium binding in NaK2K.The Journal of general physiology · 2014Article
- A computational study of barium blockades in the KcsA potassium channel based on multi-ion potential of mean force calculations and free energy perturbation.The Journal of general physiology · 2013Article
- External Ba2+ block of the two-pore domain potassium channel TREK-1 defines conformational transition in its selectivity filter.The Journal of biological chemistry · 2011Article
- Potassium-selective block of barium permeation through single KcsA channels.The Journal of general physiology · 2011Article
- Metal-driven operation of the human large-conductance voltage- and Ca2+-dependent potassium channel (BK) gating ring apparatus.The Journal of biological chemistry · 2011Article
- The relationship between duration of initial alcohol exposure and persistence of molecular tolerance is markedly nonlinear.The Journal of neuroscience : the official journal of the Society for Neuroscience · 2011Article
- Two mechanisms of ion selectivity in protein binding sites.Proceedings of the National Academy of Sciences of the United States of America · 2010Article
- Quinidine interaction with Shab K+ channels: pore block and irreversible collapse of the K+ conductance.The Journal of physiology · 2010Article
- Hydration number, topological control, and ion selectivity.The journal of physical chemistry. B · 2009Article
- Stability of the Shab K+ channel conductance in 0 K+ solutions: the role of the membrane potential.Biophysical journal · 2007Article
- Evidence for a deep pore activation gate in small conductance Ca2+-activated K+ channels.The Journal of general physiology · 2007Article
- Article
- Functional role and affinity of inorganic cations in stabilizing the tetrameric structure of the KcsA K+ channel.The Journal of general physiology · 2005Article
- K+-dependent stability and ion conduction of Shab K+ channels: a comparison with Shaker channels.Pflugers Archiv : European journal of physiology · 2005Article
- Regulation by external K+ in a maize inward shaker channel targets transport activity in the high concentration range.The Plant cell · 2005Article
- Selectivity and interactions of Ba2+ and Cs+ with wild-type and mutant TASK1 K+ channels expressed in Xenopus oocytes.The Journal of physiology · 2005Article
- Regulation of K+ flow by a ring of negative charges in the outer pore of BKCa channels. Part II: Neutralization of aspartate 292 reduces long channel openings and gating current slow component.The Journal of general physiology · 2004Article
Corrections and comments
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Authors and funding
3 authors at 2 institutions in 2 countries.
Funding
No grant is acknowledged in the PubMed record.
Abstract
Using Ba2+ as a probe, we performed a detailed characterization of an external K+ binding site located in the pore of a large conductance Ca2+-activated K+ (BKCa) channel from skeletal muscle incorporated into planar lipid bilayers. Internal Ba2+ blocks BKCa channels and decreasing external K+ using a K+ chelator, (+)-18-Crown-6-tetracarboxylic acid, dramatically reduces the duration of the Ba2+-blocked events. Average Ba2+ dwell time changes from 10 s at 10 mM external K+ to 100 ms in the limit of very low [K+]. Using a model where external K+ binds to a site hindering the exit of Ba2+ toward the external side (Neyton, J., and C. Miller. 1988. J. Gen. Physiol. 92:549-568), we calculated a dissociation constant of 2.7 mircoM for K) at this lock-in site. We also found that BK(Ca) channels enter into a long-lasting nonconductive state when the external [K+] is reduced below 4 microM using the crown ether. Channel activity can be recovered by adding K+, Rb+, Cs+, or NH4+ to the external solution. These results suggest that the BK(Ca) channel stability in solutions of very low [K+] is due to K+ binding to a site having a very high affinity. Occupancy of this site by K+ avoids the channel conductance collapse and the exit of Ba2+ toward the external side. External tetraethylammonium also reduced the Ba2+ off rate and impeded the channel from entering into the long-lasting nonconductive state. This effect requires the presence of external K+. It is explained in terms of a model in which the conduction pore contains Ba2+, K+, and tetraethylammonium simultaneously, with the K+ binding site located internal to the tetraethylammonium site. Altogether, these results and the known potassium channel structure (Doyle, D.A., J.M. Cabral, R.A. Pfuetzner, A. Kuo, J.M. Gulbis, S.L. Cohen, B.T. Chait, and R. MacKinnon. 1998. Science. 280:69-77) imply that the lock-in site and the Ba2+ sites are the external and internal ion sites of the selectivity filter, respectively.
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