Second-Site Revertants of a Low-Sodium-Affinity Mutant of the Na+/H+Exchanger Reveal the Participation of TM4 into a Highly Constrained Sodium-Binding Site†

Biochemistry ◽  
2001 ◽  
Vol 40 (16) ◽  
pp. 5095-5101 ◽  
Author(s):  
Nicolas Touret ◽  
Philippe Poujeol ◽  
Laurent Counillon
Keyword(s):  
Binding Site ◽  
Low Sodium ◽  
Sodium Binding

scholarly journals Function Trumps Form in Two Sugar Symporters, LacY and vSGLT

2021 ◽  
Vol 22 (7) ◽  
pp. 3572
Author(s):  
Jeff Abramson ◽  
Ernest M. Wright
Keyword(s):  
Binding Site ◽  
Sugar Transport ◽  
Electrochemical Potential ◽  
Inverted Repeats ◽  
Side Chains ◽  
Transmembrane Helices ◽  
Central Cavity ◽  
Potential Gradients ◽  
Sodium Binding ◽  
Major Facilitator

Active transport of sugars into bacteria occurs through symporters driven by ion gradients. LacY is the most well-studied proton sugar symporter, whereas vSGLT is the most characterized sodium sugar symporter. These are members of the major facilitator (MFS) and the amino acid-Polyamine organocation (APS) transporter superfamilies. While there is no structural homology between these transporters, they operate by a similar mechanism. They are nano-machines driven by their respective ion electrochemical potential gradients across the membrane. LacY has 12 transmembrane helices (TMs) organized in two 6-TM bundles, each containing two 3-helix TM repeats. vSGLT has a core structure of 10 TM helices organized in two inverted repeats (TM 1–5 and TM 6–10). In each case, a single sugar is bound in a central cavity and sugar selectivity is determined by hydrogen- and hydrophobic- bonding with side chains in the binding site. In vSGLT, the sodium-binding site is formed through coordination with carbonyl- and hydroxyl-oxygens from neighboring side chains, whereas in LacY the proton (H3O+) site is thought to be a single glutamate residue (Glu325). The remaining challenge for both transporters is to determine how ion electrochemical potential gradients drive uphill sugar transport.

scholarly journals Evolution of chemokine receptors is driven by mutations in the sodium binding site

2018 ◽  
Vol 14 (6) ◽  
pp. e1006209 ◽  
Author(s):  
Bruck Taddese ◽  
Madeline Deniaud ◽  
Antoine Garnier ◽  
Asma Tiss ◽  
Hajer Guissouma ◽  
...  
Keyword(s):  
Binding Site ◽  
Chemokine Receptors ◽  
Sodium Binding

scholarly journals Transfer of TRPV1 Sodium Binding Site into TRPV2

2017 ◽  
Vol 112 (3) ◽  
pp. 114a
Author(s):  
Katherine E. Huffer ◽  
Andrés Jara-Oseguera ◽  
Kenton J. Swartz
Keyword(s):  
Binding Site ◽  
Sodium Binding

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.

Sodium Binding Site of Factor Xa:  Role of Sodium in the Prothrombinase Complex†

Biochemistry ◽  
2000 ◽  
Vol 39 (7) ◽  
pp. 1817-1825 ◽  
Author(s):  
Alireza R. Rezaie ◽  
Xuhua He
Keyword(s):  
Binding Site ◽  
Factor Xa ◽  
Prothrombinase Complex ◽  
Sodium Binding

Sodium ion binding in human serum.

1982 ◽  
Vol 28 (3) ◽  
pp. 449-452 ◽  
Author(s):  
T R Kissel ◽  
J R Sandifer ◽  
N Zumbulyadis
Keyword(s):  
Standard Addition ◽  
Sodium Ion ◽  
Ion Selective Electrode ◽  
Ion Selective Electrodes ◽  
Ion Binding ◽  
Selective Electrode ◽  
Titration Method ◽  
Low Sodium ◽  
Human Sera ◽  
Sodium Binding

Abstract The amount of sodium ion binding in human sera and in dialyzed human sera was estimated from standard-addition titrations with an ion-selective electrode and from measurements of 23Na nuclear magnetic resonance (NMR) linewidth. For the untreated sera, maximum binding was 1% (1.4 mmol/L) as indicated by NMR; virtually no binding was found via the titration method. For dialyzed sera with low-sodium, normal-protein content, NMR indicated that sodium binding was less than 1.3% (0.14 mmol/L). The same dialyzed fluid analyzed with ion-selective electrodes shows no sodium binding, within the limits of experimental error (+/- 4%). Sodium ion binding to serum protein thus contributes only minimally to differences in sodium measurements observed between the direct (undiluted) ion-selective electrode and flame-photometric methods.

Sodium-Binding Site Types in Proteins

2013 ◽  
pp. 2112-2118 ◽  
Author(s):  
Bogdan Lev ◽  
Benoît Roux ◽  
Sergei Yu. Noskov
Keyword(s):  
Binding Site ◽  
Sodium Binding ◽  
Site Types
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