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Electrostatic Stabilization Plays a Central Role in Autoinhibitory Regulation of the Na<sup>+</sup>,K<sup>+</sup>-ATPase

Electrostatic Stabilization Plays a Central Role in Autoinhibitory Regulation of the Na+,K+-ATPase

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JIANG, Qiucen, Alvaro GARCIA, Minwoo HAN, Flemming CORNELIUS, Hans-Jürgen APELL, Himanshu KHANDELIA, Ronald J. CLARKE, 2017. Electrostatic Stabilization Plays a Central Role in Autoinhibitory Regulation of the Na+,K+-ATPase. In: Biophysical Journal. 112(2), pp. 288-299. ISSN 0006-3495. eISSN 1542-0086. Available under: doi: 10.1016/j.bpj.2016.12.008

@article{Jiang2017-01-24Elect-37891, title={Electrostatic Stabilization Plays a Central Role in Autoinhibitory Regulation of the Na+,K+-ATPase}, year={2017}, doi={10.1016/j.bpj.2016.12.008}, number={2}, volume={112}, issn={0006-3495}, journal={Biophysical Journal}, pages={288--299}, author={Jiang, Qiucen and Garcia, Alvaro and Han, Minwoo and Cornelius, Flemming and Apell, Hans-Jürgen and Khandelia, Himanshu and Clarke, Ronald J.} }

Khandelia, Himanshu The Na<sup>+</sup>,K<sup>+</sup>-ATPase is present in the plasma membrane of all animal cells. It plays a crucial role in maintaining the Na<sup>+</sup> and K<sup>+</sup> electrochemical potential gradients across the membrane, which are essential in numerous physiological processes, e.g., nerve, muscle, and kidney function. Its cellular activity must, therefore, be under tight metabolic control. Consideration of eosin fluorescence and stopped-flow kinetic data indicates that the enzyme's E2 conformation is stabilized by electrostatic interactions, most likely between the N-terminus of the protein's catalytic α-subunit and the adjacent membrane. The electrostatic interactions can be screened by increasing ionic strength, leading to a more evenly balanced equilibrium between the E1 and E2 conformations. This represents an ideal situation for effective regulation of the Na<sup>+</sup>,K<sup>+</sup>-ATPase's enzymatic activity, because protein modifications, which perturb this equilibrium in either direction, can then easily lead to activation or inhibition. The effect of ionic strength on the E1:E2 distribution and the enzyme's kinetics can be mathematically described by the Gouy-Chapman theory of the electrical double layer. Weakening of the electrostatic interactions and a shift toward E1 causes a significant increase in the rate of phosphorylation of the enzyme by ATP. Electrostatic stabilization of the Na<sup>+</sup>,K<sup>+</sup>-ATPase's E2 conformation, thus, could play an important role in regulating the enzyme's physiological catalytic turnover. Han, Minwoo Garcia, Alvaro Khandelia, Himanshu Cornelius, Flemming Han, Minwoo Clarke, Ronald J. Jiang, Qiucen Apell, Hans-Jürgen Electrostatic Stabilization Plays a Central Role in Autoinhibitory Regulation of the Na<sup>+</sup>,K<sup>+</sup>-ATPase Cornelius, Flemming Jiang, Qiucen 2017-03-07T14:48:50Z 2017-03-07T14:48:50Z Apell, Hans-Jürgen Clarke, Ronald J. 2017-01-24 eng Garcia, Alvaro

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