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Extracellular Allosteric Na<sup>+</sup> Binding to the Na<sup>+</sup>,K<sup>+</sup>-ATPase in Cardiac Myocytes

Extracellular Allosteric Na+ Binding to the Na+,K+-ATPase in Cardiac Myocytes

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GARCIA, Alvaro, Natasha A.S. FRY, Keyvan KARIMI, Chia-chi LIU, Hans-Jürgen APELL, Helge RASMUSSEN, Ronald CLARKE, 2013. Extracellular Allosteric Na+ Binding to the Na+,K+-ATPase in Cardiac Myocytes. In: Biophysical Journal. 105(12), pp. 2695-2705. ISSN 0006-3495. eISSN 1542-0086

@article{Garcia2013-12-17Extra-25574, title={Extracellular Allosteric Na+ Binding to the Na+,K+-ATPase in Cardiac Myocytes}, year={2013}, doi={10.1016/j.bpj.2013.11.004}, number={12}, volume={105}, issn={0006-3495}, journal={Biophysical Journal}, pages={2695--2705}, author={Garcia, Alvaro and Fry, Natasha A.S. and Karimi, Keyvan and Liu, Chia-chi and Apell, Hans-Jürgen and Rasmussen, Helge and Clarke, Ronald} }

Fry, Natasha A.S. Karimi, Keyvan Biophysical Journal ; 105 (2013), 12. - S. 2695-2705 2013-12-17 2014-01-10T10:54:02Z Garcia, Alvaro Clarke, Ronald Liu, Chia-chi Apell, Hans-Jürgen Whole-cell patch-clamp measurements of the current, Ip, produced by the Na+,K+-ATPase across the plasma membrane of rabbit cardiac myocytes show an increase in Ip over the extracellular Na+ concentration range 0–50 mM. This is not predicted by the classical Albers-Post scheme of the Na+,K+-ATPase mechanism, where extracellular Na+ should act as a competitive inhibitor of extracellular K+ binding, which is necessary for the stimulation of enzyme dephosphorylation and the pumping of K+ ions into the cytoplasm. The increase in Ip is consistent with Na+ binding to an extracellular allosteric site, independent of the ion transport sites, and an increase in turnover via an acceleration of the rate-determining release of K+ to the cytoplasm, E2(K+)2 → E1 + 2K+. At normal physiological concentrations of extracellular Na+ of 140 mM, it is to be expected that binding of Na+ to the allosteric site would be nearly saturated. Its purpose would seem to be simply to optimize the enzyme’s ion pumping rate under its normal physiological conditions. Based on published crystal structures, a possible location of the allosteric site is within a cleft between the α- and β-subunits of the enzyme Apell, Hans-Jürgen Rasmussen, Helge deposit-license Karimi, Keyvan Rasmussen, Helge eng Liu, Chia-chi Extracellular Allosteric Na<sup>+</sup> Binding to the Na<sup>+</sup>,K<sup>+</sup>-ATPase in Cardiac Myocytes Garcia, Alvaro Clarke, Ronald Fry, Natasha A.S.

Dateiabrufe seit 01.10.2014 (Informationen über die Zugriffsstatistik)

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