Evidence for the existence of two ATP-sensitive Rb+ occlusion pockets within the transmembrane domains of Na+/K+-ATPase.

The Journal of Biological Chemistry
L Liu, A Askari

Abstract

A trypsin-digested Na+/K+-ATPase that has lost ATPase activity and about half of its protein content retains an essentially intact beta-subunit, the 10 transmembrane domains of the alpha-subunit, and the full capacity to occlude Na+ and Rb+ (a congener of K+). When this preparation was incubated at 37 degrees C in the absence of Rb+, it lost half of its Rb+ occluding capacity and two-thirds of its Na+ occluding capacity. Comparison of the Rb+ occlusion-deocclusion kinetics of the digested enzyme before and after partial inactivation indicated that (a) the affinities of the labile and the stable halves of occluded Rb+ were the same; (b) occlusion and deocclusion rates of the stable pool were lower than those of the labile pool; (c) ATP at a low affinity site (K0.5 = 25-300 microM) increased deocclusion rate in the stable pool and occlusion rate in the labile pool; (d) Na+ increased Rb+ deocclusion rate of the sum of the two pools but not that of the stable pool; and (e) occlusion and deocclusion rates of both pools were decreased by ouabain. These findings suggest that (a) the peptide complex of the digested enzyme contains two distinct but interacting cation occlusion pockets, one occluding two Na+ or one Rb+, and the other occ...Continue Reading

References

Jan 1, 1990·Annual Review of Biochemistry·I M Glynn, S J Karlish
Jan 1, 1990·The American Journal of Physiology·C H Pedemonte, J H Kaplan
Jun 1, 1990·Proceedings of the National Academy of Sciences of the United States of America·S J KarlishW D Stein
Nov 2, 1987·Biochimica Et Biophysica Acta·M ShaniS J Karlish
Aug 1, 1987·Journal of Bioenergetics and Biomembranes·A Askari
Aug 15, 1995·Proceedings of the National Academy of Sciences of the United States of America·S LutsenkoJ H Kaplan
Jun 16, 1995·The Journal of Biological Chemistry·J C KosterR W Mercer
Jun 30, 1995·The Journal of Biological Chemistry·M GanjeizadehA Askari
Apr 1, 1994·The Journal of General Physiology·F JaisserJ D Horisberger
Oct 11, 1996·The Journal of Biological Chemistry·T Arato-OshimaH Homareda
Nov 22, 1996·The Journal of Biological Chemistry·T A KuntzweilerJ B Lingrel
Dec 13, 1996·The Journal of Biological Chemistry·E C RabonK Smillie
Mar 21, 1997·The Journal of Biological Chemistry·N A SarvazyanA Askari

❮ Previous
Next ❯

Citations

Jun 25, 2003·The Journal of Membrane Biology·M T TostesonD C Tosteson
Oct 9, 2001·European Journal of Biochemistry·A V GrinbergV Y Grinberg
Jul 20, 1999·The Journal of Biological Chemistry·S B KaufmanR C Rossi
Feb 8, 2002·American Journal of Physiology. Renal Physiology·Elena ArystarkhovaKathleen J Sweadner
May 21, 1999·Analytical Biochemistry·R C RossiP J Garrahan

❮ Previous
Next ❯

Related Concepts

Related Feeds

ASBMB Publications

The American Society for Biochemistry and Molecular Biology (ASBMB) includes the Journal of Biological Chemistry, Molecular & Cellular Proteomics, and the Journal of Lipid Research. Discover the latest research from ASBMB here.