A transmembrane segment determines the steady-state localization of an ion-transporting adenosine triphosphatase

J Cell Biol. 2000 Feb 21;148(4):769-78. doi: 10.1083/jcb.148.4.769.

Abstract

The H,K-adenosine triphosphatase (ATPase) of gastric parietal cells is targeted to a regulated membrane compartment that fuses with the apical plasma membrane in response to secretagogue stimulation. Previous work has demonstrated that the alpha subunit of the H, K-ATPase encodes localization information responsible for this pump's apical distribution, whereas the beta subunit carries the signal responsible for the cessation of acid secretion through the retrieval of the pump from the surface to the regulated intracellular compartment. By analyzing the sorting behaviors of a number of chimeric pumps composed of complementary portions of the H, K-ATPase alpha subunit and the highly homologous Na,K-ATPase alpha subunit, we have identified a portion of the gastric H,K-ATPase, which is sufficient to redirect the normally basolateral Na,K-ATPase to the apical surface in transfected epithelial cells. This motif resides within the fourth of the H,K-ATPase alpha subunit's ten predicted transmembrane domains. Although interactions with glycosphingolipid-rich membrane domains have been proposed to play an important role in the targeting of several apical membrane proteins, the apically located chimeras are not found in detergent-insoluble complexes, which are typically enriched in glycosphingolipids. Furthermore, a chimera incorporating the Na, K-ATPase alpha subunit fourth transmembrane domain is apically targeted when both of its flanking sequences derive from H,K-ATPase sequence. These results provide the identification of a defined apical localization signal in a polytopic membrane transport protein, and suggest that this signal functions through conformational interactions between the fourth transmembrane spanning segment and its surrounding sequence domains.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Biological Transport
  • Cations / metabolism
  • Cell Line
  • Cell Membrane / drug effects
  • Cell Membrane / enzymology*
  • Cell Membrane / metabolism
  • Cell Polarity*
  • Glycosphingolipids / metabolism
  • Glycosylphosphatidylinositols / metabolism
  • H(+)-K(+)-Exchanging ATPase / analysis*
  • H(+)-K(+)-Exchanging ATPase / chemistry*
  • H(+)-K(+)-Exchanging ATPase / genetics
  • H(+)-K(+)-Exchanging ATPase / metabolism
  • Hydrogen-Ion Concentration
  • Membrane Proteins / analysis
  • Membrane Proteins / chemistry
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism
  • Molecular Sequence Data
  • Ouabain / pharmacology
  • Parietal Cells, Gastric / cytology
  • Parietal Cells, Gastric / drug effects
  • Parietal Cells, Gastric / enzymology*
  • Parietal Cells, Gastric / metabolism
  • Protein Sorting Signals / chemistry
  • Protein Sorting Signals / genetics
  • Protein Sorting Signals / physiology*
  • Recombinant Fusion Proteins / analysis
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Sequence Alignment
  • Sequence Deletion / genetics
  • Sodium-Potassium-Exchanging ATPase / antagonists & inhibitors
  • Sodium-Potassium-Exchanging ATPase / chemistry
  • Sodium-Potassium-Exchanging ATPase / genetics
  • Sodium-Potassium-Exchanging ATPase / metabolism
  • Solubility
  • Transfection

Substances

  • Cations
  • Glycosphingolipids
  • Glycosylphosphatidylinositols
  • Membrane Proteins
  • Protein Sorting Signals
  • Recombinant Fusion Proteins
  • Ouabain
  • H(+)-K(+)-Exchanging ATPase
  • Sodium-Potassium-Exchanging ATPase