The alpha-subunit of the colonic H+,K+-ATPase assembles with beta1-Na+,K+-ATPase in kidney and distal colon.
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 alpha-subunit of the colonic H+, K+-ATPase (HKalpha2) requires coexpression with a beta-subunit to support H+/K+ transport in a heterologous expression system (Xenopus laevis oocytes). In these studies, HKalpha2 formed stable and functional alpha.beta complexes when coexpressed with either the rat beta1-subunit of the Na+,K+-ATPase or the beta-subunit of the gastric H+,K+-ATPase, suggesting that different beta-subunits may interact with HKalpha2. The present studies tested this hypothesis by development and application of a specific antibody against HKalpha2 peptide. Subsequently, immunoprecipitation experiments were performed to determine if HKalpha2 co-precipitates with the same beta-subunit in organs known to express HKalpha2 protein. The data demonstrate that HKalpha2 assembles with beta1-Na+,K+-ATPase in the renal medulla and in distal colon.
Codina
J
J
Division of Renal Diseases and Hypertension, Department of Internal Medicine, University of Texas, Houston Medical School, Houston, Texas 77030, USA.
Delmas-Mata
J T
JT
DuBose
T D
TD
D000818:Animals; D000906:Antibodies / Q000276:immunology; D000918:Antibody Specificity; D003106:Colon / Q000201:enzymology*; D003429:Cross Reactions; D017506:H(+)-K(+)-Exchanging ATPase / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D007668:Kidney / Q000201:enzymology*; D008297:Male; D009928:Organ Specificity / Q000276:immunology; D051381:Rats; D017207:Rats, Sprague-Dawley; D000254:Sodium-Potassium-Exchanging ATPase / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*
D000906:Antibodies; D017506:H(+)-K(+)-Exchanging ATPase; D000254:Sodium-Potassium-Exchanging ATPase