Stabilization of the H,K-ATPase M5M6 membrane hairpin by K+ ions. Mechanistic significance for P2-type ATPases

Craig Gatto, Svetlana Lutsenko, Jai Moo Shin, George Sachs, Jack H. Kaplan

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38 Scopus citations


The integral membrane protein, the gastric H,K-ATPase, is an α-β heterodimer, with 10 putative transmembrane segments in the α-subunit and one such segment in the β-subunit. All transmembrane segments remain within the membrane domain following trypsinization of the intact gastric H,K- ATPase in the presence of K+ ions, identified as M1M2, M3M4, M5M6, and M7, M8, M9, and M10. Removal of K+ ions from this digested preparation results in the selective loss of the M5M6 hairpin from the membrane. The release of the M5M6 fragment is directed to the extracellular phase as evidenced by the accumulation of the released M5M6 hairpin inside the sealed inside out vesicles. The stabilization of the M5M6 hairpin in the membrane phase by the transported cation as well as loss to the aqueous phase in the absence of the transported cation has been previously observed for another P2-type ATPase, the Na,K-ATPase (Lutsenko, S., Anderko, R., and Kaplan, J. H. (1995) Proc. Natl. Acad. Sci. U. S. A. 92, 7936-7940). Thus, the effects of the counter- transported cation on retention of the M5M6 segment in the membrane as compared with the other membrane pairs may be a general feature of P2- ATPase ion pumps, reflecting a flexibility of this region that relates to the mechanism of transport.

Original languageEnglish (US)
Pages (from-to)13737-13740
Number of pages4
JournalJournal of Biological Chemistry
Issue number20
StatePublished - May 14 1999
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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