Ion Selectivity Strategies of Sodium Channel Selectivity Filters

2014 ◽  
Vol 47 (12) ◽  
pp. 3580-3587 ◽  
Author(s):  
Todor Dudev ◽  
Carmay Lim
Keyword(s):  
Sodium Channel ◽  
Ion Selectivity ◽  
Channel Selectivity

scholarly journals The Origins of Ion Selectivity in a Bacterial Sodium Channel Revealed by μS-Long Simulations

2014 ◽  
Vol 106 (2) ◽  
pp. 131a
Author(s):  
Celine Boiteux ◽  
Igor Vorobyov ◽  
Toby W. Allen
Keyword(s):  
Sodium Channel ◽  
Ion Selectivity

scholarly journals Fluorine-19 NMR and computational quantification of isoflurane binding to the voltage-gated sodium channel NaChBac

2016 ◽  
Vol 113 (48) ◽  
pp. 13762-13767 ◽  
Author(s):  
Monica N. Kinde ◽  
Vasyl Bondarenko ◽  
Daniele Granata ◽  
Weiming Bu ◽  
Kimberly C. Grasty ◽  
...  
Keyword(s):  
Sodium Channel ◽  
Binding Sites ◽  
Ion Selectivity ◽  
Selectivity Filter ◽  
Inactivation Kinetics ◽  
Voltage Gated Sodium Channel ◽  
Voltage Gated ◽  
Voltage Gated Sodium Channels ◽  
Binding Data ◽  
Quantitative Analyses

Voltage-gated sodium channels (NaV) play an important role in general anesthesia. Electrophysiology measurements suggest that volatile anesthetics such as isoflurane inhibit NaVby stabilizing the inactivated state or altering the inactivation kinetics. Recent computational studies suggested the existence of multiple isoflurane binding sites in NaV, but experimental binding data are lacking. Here we use site-directed placement of19F probes in NMR experiments to quantify isoflurane binding to the bacterial voltage-gated sodium channel NaChBac.19F probes were introduced individually to S129 and L150 near the S4–S5 linker, L179 and S208 at the extracellular surface, T189 in the ion selectivity filter, and all phenylalanine residues. Quantitative analyses of19F NMR saturation transfer difference (STD) spectroscopy showed a strong interaction of isoflurane with S129, T189, and S208; relatively weakly with L150; and almost undetectable with L179 and phenylalanine residues. An orientation preference was observed for isoflurane bound to T189 and S208, but not to S129 and L150. We conclude that isoflurane inhibits NaChBac by two distinct mechanisms: (i) as a channel blocker at the base of the selectivity filter, and (ii) as a modulator to restrict the pivot motion at the S4–S5 linker and at a critical hinge that controls the gating and inactivation motion of S6.

scholarly journals A Novel Point Mutation in the KCNJ5 Gene Causing Primary Hyperaldosteronism and Early-Onset Autosomal Dominant Hypertension

2012 ◽  
Vol 97 (8) ◽  
pp. E1532-E1539 ◽  
Author(s):  
Evangelia Charmandari ◽  
Amalia Sertedaki ◽  
Tomoshige Kino ◽  
Christina Merakou ◽  
Dax A. Hoffman ◽  
...  
Keyword(s):  
Early Onset ◽  
Ion Selectivity ◽  
Zona Glomerulosa ◽  
Primary Hyperaldosteronism ◽  
K Channel ◽  
Nucleotide Position ◽  
Coding Regions ◽  
Channel Selectivity ◽  
Electrophysiological Studies ◽  
Aldosterone Production

Abstract Context: Aldosterone production in the adrenal zona glomerulosa is mainly regulated by angiotensin II, [K+], and ACTH. Genetic deletion of subunits of K+-selective leak (KCNK) channels TWIK-related acid sensitive K+-1 and/or TWIK-related acid sensitive K+-3 in mice results in primary hyperaldosteronism, whereas mutations in the KCNJ5 (potassium inwardly rectifying channel, subfamily J, member 5) gene are implicated in primary hyperaldosteronism and, in certain cases, in autonomous glomerulosa cell proliferation in humans. Objective: The objective of the study was to investigate the role of KCNK3, KCNK5, KCNK9, and KCNJ5 genes in a family with primary hyperaldosteronism and early-onset hypertension. Patients and Methods: Two patients, a mother and a daughter, presented with severe primary hyperaldosteronism, bilateral massive adrenal hyperplasia, and early-onset hypertension refractory to medical treatment. Genomic DNA was isolated and the exons of the entire coding regions of the above genes were amplified and sequenced. Electrophysiological studies were performed to determine the effect of identified mutation(s) on the membrane reversal potentials. Results: Sequencing of the KCNJ5 gene revealed a single, heterozygous guanine to thymine (G → T) substitution at nucleotide position 470 (n.G470T), resulting in isoleucine (I) to serine (S) substitution at amino acid 157 (p.I157S). This mutation results in loss of ion selectivity, cell membrane depolarization, increased Ca2+ entry in adrenal glomerulosa cells, and increased aldosterone synthesis. Sequencing of the KCNK3, KCNK5, and KCNK9 genes revealed no mutations in our patients. Conclusions: These findings explain the pathogenesis in a subset of patients with severe hypertension and implicate loss of K+ channel selectivity in constitutive aldosterone production.

scholarly journals Influx of calcium, strontium, and barium in presynaptic nerve endings.

1982 ◽  
Vol 79 (6) ◽  
pp. 1065-1087 ◽  
Author(s):  
D A Nachshen ◽  
M P Blaustein
Keyword(s):  
Divalent Cation ◽  
Binding Sites ◽  
Divalent Cations ◽  
Ion Selectivity ◽  
Permeability Ratio ◽  
Low Concentrations ◽  
Slow Channel ◽  
Channel Selectivity ◽  
High Concentrations ◽  
Two Phases

Depolarization-induced (potassium-stimulated) influx of 45Ca, 85Sr, and 133Ba was measured in synaptosomes prepared from rat brain. There are two phases of divalent cation entry, "fast" and "slow;" each phase is mediated by channels with distinctive characteristics. The fast channels inactivate (within 1 s) and are blocked by low concentrations (less than 1 micro M) of La. The slow channels do not inactivate (within 10 s), and are blocked by high concentrations (greater than 50 micro M) of La. Divalent cation influx through both channels saturates with increasing concentrations of permeant divalent cation; in addition, each permeant divalent cation species competitively blocks the influx of other permeant species. These results are consistent with the presence of "binding sites" for divalent cations in the fast and slow channels. The Ca:Sr:Ba permeability ratio, determined by measuring the influx of all three species in triple-label experiments, was 6:3:2 for the fast channel and 6:3:1 for the slow channel. A simple model for ion selectivity, based on the presence of a binding site in the channel, could account well for slow and, to some extent, for fast, channel selectivity data.

scholarly journals Bases of Sodium Channel Selectivity Among Organic Cations

2016 ◽  
Vol 110 (3) ◽  
pp. 322a
Author(s):  
Yibo Wang ◽  
Rocio K. Finol-Urdaneta ◽  
Sergei Yu Noskov ◽  
Robert J. French
Keyword(s):  
Sodium Channel ◽  
Organic Cations ◽  
Channel Selectivity

scholarly journals Modified kinetics and selectivity of sodium channels in frog skeletal muscle fibers treated with aconitine.

1982 ◽  
Vol 80 (5) ◽  
pp. 713-731 ◽  
Author(s):  
D T Campbell
Keyword(s):  
Skeletal Muscle ◽  
Sodium Channel ◽  
Sodium Channels ◽  
State Level ◽  
Steady State Level ◽  
Channel Block ◽  
Frog Skeletal Muscle ◽  
Channel Kinetics ◽  
Ionic Selectivity ◽  
Channel Selectivity

The effect of the plant alkaloid aconitine on sodium channel kinetics, ionic selectivity, and blockage by protons and tetrodotoxin (TTX) has been studied in frog skeletal muscle. Treatment with 0.25 or 0.3 mM aconitine alters sodium channels so that the threshold of activation is shifted 40-50 mV in the hyperpolarized direction. In contrast to previous results in frog nerve, inactivation is complete for depolarizations beyond about -60 mV. After aconitine treatment, the steady state level of inactivation is shifted approximately 20 mV in the hyperpolarizing direction. Concomitant with changes in channel kinetics, the relative permeability of the sodium channel to NH4,K, and Cs is increased. This altered selectivity is not accompanied by altered block by protons or TTX. The results suggest that sites other than those involved in channel block by protons and TTX are important in determining sodium channel selectivity.

Importance of position 8 in μ-conotoxin KIIIA for voltage-gated sodium channel selectivity

FEBS Journal ◽  
2011 ◽  
Vol 278 (18) ◽  
pp. 3408-3418 ◽  
Author(s):  
Annelies Van Der Haegen ◽  
Steve Peigneur ◽  
Jan Tytgat
Keyword(s):  
Sodium Channel ◽  
Voltage Gated Sodium Channel ◽  
Voltage Gated ◽  
Channel Selectivity

scholarly journals Sodium channel selectivity. Dependence on internal permeant ion concentration.

1976 ◽  
Vol 68 (2) ◽  
pp. 111-125 ◽  
Author(s):  
M Cahalan ◽  
T Begenisich
Keyword(s):  
Sodium Channel ◽  
Ion Concentration ◽  
Selectivity Ratio ◽  
Squid Axon ◽  
Perfusion Medium ◽  
Chloride Permeability ◽  
Channel Selectivity ◽  
Sucrose Solutions ◽  
Internal Concentration ◽  
Reversal Potentials

The selectivity of sodium channels in squid axon membranes was investigated with widely varying concentrations of internal ions. The selectivity ratio, PNa/PK, determined from reversal potentials decreases from 12.8 to 5.7 to 3.5 as the concentration of internal potassium is reduced from 530 to 180 to 50 mM, respectively. The internal KF perfusion medium can be diluted by tetramethylammonium (TMA), Tris, or sucrose solutions with the same decrease in PNa/PK. The changes in the selectivity ratio depend upon internal permeant ion concentration rather than ionic strength, membrane potential, or chloride permeability. Lowering the internal concentration of cesium, rubidium, guanidnium, or ammonium also reduces PNa/Pion. The selective sequence of the sodium channel is: Na greater than guanidinium greater than ammonium greater than K greater than Rb greater than Cs.

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