Primary structure of the xenopus and murine alpha-subunit of the gastric
h,k -atpase and functional expression in xenopus oocytes.
Mathews, Paul M., Dirk Claeys, Fr[acute]ed[acute]eric Jaisser, Kathi Geering,
Jean-Daniel, Horisberger, Jean-Pierre Kraehenbuhl, and Bernard C. Rossier.
Institute of Pharmacology and Toxicology, University of Lausanne, Rue du
Bugnon 27, CH-1005 Lausanne, Switzerland, Swiss Institute of Experimental
Cancer Research, Epalinges/Lausanne and Institute of Biochemistry, University
of LausanneChemin des Boveresses 155, CH-1066 Epalinges/Lausanne,
Switzerland.
APStracts 2:0034C, 1995.
The H,K-ATPase of the gastric parietal cells is responsible for the
acidification of the stomach lumen. This heterodimeric protein belongs to the
family of cation translocating P-type ATPases which includes the closely
related Na,K-ATPase. We have cloned the [alpha]-subunit cDNA of the Xenopus
and murine gastric H,K-ATPase ([alpha]H,K). We have expressed Xenopus and
murine [alpha]H,K along with the previously cloned gastric H,K-ATPase [beta]-
subunit of rabbit ([beta]H,K) in Xenopus oocytes by cRNA injection. An
antibody directed against the [beta]H,K co-immunoprecipitates under non-
denaturing conditions the [alpha]H,K of both species, demonstrating assembly
of the [alpha]/[beta] complex. Additionally, we demonstrate the presence of K+
transporting H,K-ATPase in the plasma membrane of oocytes by 86Rb+ uptake. The
H,K-ATPase mediated K+ uptake was inhibited by the gastric H,K-ATPase
inhibitor SCH 28080, but not by ouabain, and shows K+-dependent activation
(K1/2 2 mM). Further, H,K-ATPase expressing oocytes show a SCH 28080
inhibitable proton extrusion. Our data indicate that the expressed H,K-ATPase
behaves functionally in oocytes as in the gastric gland.
Received 1 July 1994; accepted in final form 17 November 1994
APS Manuscript Number C0377-4.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1994 The American Physiological Society.
Published in APStracts on 27 February 1995.