title: Molecular characterization and expression of the (Na+ + K+)-ATPase alpha-subunit in Drosophila melanogaster.
abstract: The (Na+ + K+)-ATPase (sodium pump) is an ouabain-sensitive, electrogenic ion pump responsible for maintaining the balance of sodium and potassium ions in almost all animal cells. Robust, ouabain-sensitive rubidium uptake, indicative of the sodium pump, was found in tissue-cultured Drosophila cells, and both larvae and adults die when fed a diet containing ouabain. A monoclonal antibody to the avian sodium pump alpha-subunit was found to cross-react with the Drosophila sodium pump alpha-subunit. Immunofluorescence microscopy was used to obtain a semi-quantitative view of the expression of the sodium pump in Drosophila tissues: high levels of the sodium pump were detected in malpighian tubules, indirect flight muscles and tubular muscles, and throughout the nervous system. The cDNA encoding this sodium pump alpha-subunit in Drosophila melanogaster was cloned, sequenced and expressed in mouse L cells. At the amino acid level, its deduced sequence of 1038 residues (the first such sequence for an invertebrate) is approximately 80% similar to alpha-subunit sequences reported for vertebrates. Only one gene was found in Drosophila, located on the third chromosome at position 93B. A restriction site polymorphism has been found, and several mutations exist that may involve the alpha-subunit gene.
authors.affiliation: Department of Biology, Johns Hopkins University, Baltimore, MD 21218.
authors.forename: R M
authors.initials: RM
authors.lastname: Lebovitz
authors.forename: K
authors.initials: K
authors.lastname: Takeyasu
authors.forename: D M
authors.initials: DM
authors.lastname: Fambrough
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D002874:Chromosome Mapping; D004247:DNA / Q000235:genetics; D004331:Drosophila melanogaster / Q000201:enzymology* / Q000235:genetics; D007739:L Cells; D051379:Mice; D008969:Molecular Sequence Data; D010042:Ouabain / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D010042:Ouabain; D004247:DNA; D000254:Sodium-Potassium-Exchanging ATPase