The α-subunit of the colonic H+,K+-ATPase assembles with β1- Na+,K+-ATPase in kidney and distal colon

Abstract

Previous experiments from our laboratory (Codina, J., Kone, B.C., Delmas-Mata, J. T., and DuBose, T. D., Jr. (1996) J. Biol. Chem. 271, 29759- 29763) demonstrated that the α-subunit of the colonic H+,K+-ATPase (HKα2) requires coexpression with a β-subunit to support H+/K+ transport in a heterologous expression system (Xenopus laevis oocytes). In these studies, HKα2 formed stable and functional α·β complexes when coexpressed with either the rat β1-subunit of the Na+,K+-ATPase or the β-subunit of the gastric H+,K+-ATPase, suggesting that different β- subunits may interact with FgKα2. The present studies tested this hypothesis by development and application of a specific antibody against HkKα2 peptide. Subsequently, immunoprecipitation experiments were performed to determine if HKα2 co-precipitates with the same β-subunit in organs known to express HKα2 protein. The data demonstrate that KHα2 assembles with β1-Na+,K+-ATPase in the renal medulla and in distal colon.