Mutational effects on conformational changes of the dephospho- and phospho-forms of the Na+,K+-ATPase

Biochemistry
Mads S Toustrup-JensenBente Vilsen

Abstract

Gly263 of the rat kidney Na(+),K(+)-ATPase is highly conserved within the family of P-type ATPases. Mutants in which Gly263 or the juxtaposed Arg264 had been replaced by alanine were expressed at high levels in COS-1 cells and characterized functionally. Titrations of Na(+),K(+), ATP, and vanadate dependencies of Na(+),K(+)-ATPase activity showed changes in the apparent affinities relative to wild-type compatible with a displacement of the E(1)-E(2) conformational equilibrium in favor of E(1). The level of the K(+)-occluded form was reduced in the Gly263-->Ala and Arg264-->Ala mutants, and the rate constant characterizing deocclusion of K(+) or Rb(+) was increased as much as 20-fold in the Gly263-->Ala mutant. Studies of the sensitivity of the phosphoenzyme to K(+) and ADP showed a displacement of the E(1)P-E(2)P equilibrium of the phosphoenzyme in favor of E(1)P, and dephosphorylation experiments carried out at 25 degrees C on a millisecond time scale using a quenched-flow technique demonstrated a reduction of the E(1)P to E(2)P conversion rate in the mutants. Hence, the mutations displaced the conformational equilibria of dephosphoenzyme and phosphoenzyme in parallel in favor of the E(1) and E(1)P forms. The observed effects ...Continue Reading

References

Jan 1, 1990·Annual Review of Biochemistry·I M Glynn, S J Karlish
Jun 8, 1993·Biochimica Et Biophysica Acta·J D Robinson, P R Pratap
Jan 1, 1967·Annual Review of Biochemistry·R W Albers

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Citations

May 7, 2009·The Journal of Biological Chemistry·Mads S Toustrup-JensenBente Vilsen
Nov 26, 2011·The Journal of Biological Chemistry·Vivien Rodacker SchackBente Vilsen
Jun 5, 2002·Annual Review of Biochemistry·Jack H Kaplan
Jan 14, 2003·Annual Review of Physiology·Peter L JorgensenSteven J D Karlish
May 24, 2003·Annals of the New York Academy of Sciences·Bente Vilsen, Mads Toustrup-Jensen
Dec 15, 2016·Journal of Chemical Information and Modeling·Petra ČechováMartin Kubala
Aug 2, 2008·The Journal of Biological Chemistry·Vivien Rodacker SchackBente Vilsen
Feb 26, 2015·The Journal of Biological Chemistry·Rikke HolmBente Vilsen
Dec 3, 2004·The Journal of Biological Chemistry·Mads Toustrup-Jensen, Bente Vilsen
Jun 8, 2007·The Journal of Biological Chemistry·Anja Pernille EinholmBente Vilsen
May 24, 2003·Annals of the New York Academy of Sciences·Mads Toustrup-Jensen, Bente Vilsen
Sep 22, 2020·ELife·Marie E SweetDavid L Stokes

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