scholarly journals Ion Selectivity of the Cytoplasmic Binding Sites of the Na,K-ATPase: I. Sodium Binding is Associated with a Conformational Rearrangement

1999 ◽  
Vol 168 (3) ◽  
pp. 221-228 ◽  
Author(s):  
A. Schneeberger ◽  
H.-J. Apell
Keyword(s):  
Binding Sites ◽  
Ion Selectivity ◽  
Conformational Rearrangement ◽  
Sodium Binding

scholarly journals Investigation of the sodium-binding sites in the sodium-coupled betaine transporter BetP

2012 ◽  
Vol 109 (44) ◽  
pp. E3035-E3044 ◽  
Author(s):  
K. Khafizov ◽  
C. Perez ◽  
C. Koshy ◽  
M. Quick ◽  
K. Fendler ◽  
...  
Keyword(s):  
Binding Sites ◽  
Sodium Binding

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 Elevator mechanism of aspartate (glutamate) transport across the membrane

2014 ◽  
Vol 70 (a1) ◽  
pp. C1491-C1491
Author(s):  
Albert Guskov ◽  
Sonja Jensen ◽  
Stephan Rempel ◽  
Inga Hänelt ◽  
Dirk Slotboom
Keyword(s):  
Crystal Structure ◽  
Binding Site ◽  
Binding Sites ◽  
Glutamate Transporter ◽  
Sodium Ions ◽  
Binding Residue ◽  
Sodium Binding ◽  
Structural Insight ◽  
Global Similarity ◽  
Conserved Residue

Archaeal homologues of human neuronal glutamate transporter catalyze the coupled uptake of aspartate and three sodium ions. After the delivery of the substrate and sodium ions in the cytoplasm the empty binding site must reorient to the outward-facing conformation to reset the transporter. Here we present a crystal structure of the substrate-free transporter GltTk from Thermococcus kodakarensis, resolved at 3 Å resolution [1]. Despite the global similarity to the previously resolved structures of aspartate transporter GltPh, there are tremendous rearrangements in the substrate-binding site. The key binding residue Arg401 moves in and partially occupies the substrate's position, while the rotation of another conserved residue Met314 completely destroys the geometry of the sodium-binding sites. This structure provides direct structural insight in the mechanism of the essential reorientation step in the translocation cycle for this type of transporters.

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.

Interaction between cytoplasmic sodium binding sites and cardiotonic steroids

1994 ◽  
pp. 573-576
Author(s):  
B. Schwappach ◽  
W. Stürmer ◽  
H.-J. Apell ◽  
S. J. D. Karlish
Keyword(s):  
Binding Sites ◽  
Sodium Binding
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