## Modulation of the Na,K-ATPase by Magnesium Ions

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2017
##### Authors
Schreiber, Grischa
Journal article
Published
##### Published in
Biochemistry ; 56 (2017), 7. - pp. 1005-1016. - ISSN 0006-2960. - eISSN 1520-4995
##### Abstract
Since the beginning of investigations of the Na,K-ATPase, it has been well-known that Mg2+ is an essential cofactor for activation of enzymatic ATP hydrolysis without being transported through the cell membrane. Moreover, experimental evidence has been collected through the years that shows that Mg2+ ions have a regulatory effect on ion transport by interacting with the cytoplasmic side of the ion pump. Our experiments allowed us to reveal the underlying mechanism. Mg2+ is able to bind to a site outside the membrane domain of the protein's α subunit, close to the entrance of the access channel to the ion-binding sites, thus modifying the local concentration of the ions in the electrolyte, of which Na+, K+, and H+ are of physiological interest. The decrease in the concentration of these cations can be explained by electrostatic interaction and estimated by the Debye-Hückel theory. This effect provokes the observed apparent reduction of the binding affinity of the binding sites of the Na,K-ATPase in the presence of various Mg2+ concentrations. The presence of the bound Mg2+, however, does not affect the reaction kinetics of the transport function of the ion pump. Therefore, stopped-flow experiments could be performed to gain the first insight into the Na+ binding kinetics on the cytoplasmic side by Mg2+ concentration jump experiments.
##### Subject (DDC)
570 Biosciences, Biology
##### Cite This
ISO 690APELL, Hans-Jürgen, Tanja HITZLER, Grischa SCHREIBER, 2017. Modulation of the Na,K-ATPase by Magnesium Ions. In: Biochemistry. 56(7), pp. 1005-1016. ISSN 0006-2960. eISSN 1520-4995. Available under: doi: 10.1021/acs.biochem.6b01243
BibTex
@article{Apell2017-02-21Modul-37889,
year={2017},
doi={10.1021/acs.biochem.6b01243},
title={Modulation of the Na,K-ATPase by Magnesium Ions},
number={7},
volume={56},
issn={0006-2960},
journal={Biochemistry},
pages={1005--1016},
author={Apell, Hans-Jürgen and Hitzler, Tanja and Schreiber, Grischa}
}

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<dcterms:abstract xml:lang="eng">Since the beginning of investigations of the Na,K-ATPase, it has been well-known that Mg&lt;sup&gt;2+&lt;/sup&gt; is an essential cofactor for activation of enzymatic ATP hydrolysis without being transported through the cell membrane. Moreover, experimental evidence has been collected through the years that shows that Mg&lt;sup&gt;2+&lt;/sup&gt; ions have a regulatory effect on ion transport by interacting with the cytoplasmic side of the ion pump. Our experiments allowed us to reveal the underlying mechanism. Mg&lt;sup&gt;2+&lt;/sup&gt; is able to bind to a site outside the membrane domain of the protein's α subunit, close to the entrance of the access channel to the ion-binding sites, thus modifying the local concentration of the ions in the electrolyte, of which Na&lt;sup&gt;+&lt;/sup&gt;, K&lt;sup&gt;+&lt;/sup&gt;, and H&lt;sup&gt;+&lt;/sup&gt; are of physiological interest. The decrease in the concentration of these cations can be explained by electrostatic interaction and estimated by the Debye-Hückel theory. This effect provokes the observed apparent reduction of the binding affinity of the binding sites of the Na,K-ATPase in the presence of various Mg&lt;sup&gt;2+&lt;/sup&gt; concentrations. The presence of the bound Mg&lt;sup&gt;2+&lt;/sup&gt;, however, does not affect the reaction kinetics of the transport function of the ion pump. Therefore, stopped-flow experiments could be performed to gain the first insight into the Na&lt;sup&gt;+&lt;/sup&gt; binding kinetics on the cytoplasmic side by Mg&lt;sup&gt;2+&lt;/sup&gt; concentration jump experiments.</dcterms:abstract>
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Yes