Multiple forms of (Na+ + K+)-ATPase in the chicken. Selective detection of the major nerve, skeletal muscle, and kidney form by a monoclonal antibody.

Abstract

Evidence is presented that monoclonal gamma-immunoglobulin secreted by hybridoma-24 recognizes the sodium and potassium ion-stimulated ATPase of neurons, muscle fibers, and kidney tubule cells in the chicken. The antigen consists of alpha (Mr = 105,000) and beta (Mr = 47,000) subunits. Only the beta subunit bears major oligosaccharide additions (including binding sites for wheat germ agglutinin) to its polypeptide core (Mr = 32,000). The detergent-solubilized antigen sediments as a 7 S complex of alpha beta or alpha beta 2. The antigen has a basolateral distribution in the plasma membrane of renal tubule cells, and in myogenic cell cultures there is up-regulation of the antigen in low potassium medium. Monoclonal antibody-24 specifically recognizes purified gull salt gland (Na+ + K+)-ATPase as well as the major candidate molecule for the (Na+ + K+)-ATPase in enriched preparations from chicken kidney. On cultured myotubes, the number of ouabain-binding sites (4.8 X 10(5)/nucleus) and antigenic sites (4.4 X 10(5)) are approximately equal. However, the antigenic sites on fibroblasts (1.1 X 10(4)) account for only about 4% of the ouabain-binding sites, and there is little or no antibody binding to capillary endothelial cells, Schwann cells, or erythrocytes. Evidence is presented that the antigenic determinant is proteinaceous. It is concluded that at least two antigenically distinct (Na+ + K+)-ATPases exist in the chicken.