Sodium acts as a potassium analog on gastric H,K-ATPase

H. G.P. Swarts*, C. H.W. Klaassen, F. M.A.H.S. Stekhoven, J. J.H.H.M. De Pont

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

37 Citations (Scopus)
19 Downloads (Pure)

Abstract

The effects of Na+ on gastric H,K-ATPase were investigated using leaky and ion-tight H,K-ATPase vesicles. Na+ activated the total ATPase activity in the absence of K+, reaching levels of 15% relative to those in the presence of K+. The Na+ activation, which takes place at the luminal side of the membrane, depended on the ATP concentration and the type of buffer used. The steady-state ATP phosphorylation level, studied with leaky vesicles, was reduced by Na+ due to both activation of the dephosphorylation reaction and a shift to E2 in the E1 mutually implies E2 equilibrium. By studying this equilibrium in ion-tight H,K-ATPase vesicles, it was found that Na+ drives the enzyme via a cytosolic site to the nonphosphorylating E2 conformation. No H+-like properties of cytosolic Na+ could be detected. We therefore conclude that Na+ behaves like K+ rather than like H+ in the H,K-ATPase reaction.

Original languageEnglish
Pages (from-to)7890-7895
Number of pages6
JournalJournal of Biological Chemistry
Volume270
Issue number14
DOIs
Publication statusPublished - Apr 1995
Externally publishedYes

Fingerprint

Dive into the research topics of 'Sodium acts as a potassium analog on gastric H,K-ATPase'. Together they form a unique fingerprint.

Cite this