FUNCTIONAL-ANALYSIS AND TISSUE-SPECIFIC EXPRESSION OF DROSOPHILA NA-ATPASE SUBUNITS(,K+)

We have previously purified and characterized a nervous system-specifi c glycoprotein antigen from adult Drosophila heads, designated Nervana [nerve antigen (NRV)] and identified two separate genes coding for th ree different proteins. All three proteins share homology with the bet a subunits of Na+,K+-ATPase from various other species. In this study we have isolated a new Drosophila Na+,K+-ATPase alpha subunit cDNA clo ne (PS alpha; GenBank accession no. AF044974) and demonstrate expressi on of functional Na+,K+-ATPase activity when PS alpha mRNA is coinject ed into Xenopus oocytes along with any of the three different Nrv mRNA s. Western blotting, RNase protection assays, and immunocytochemical s taining of adult fly sections indicate that NRV2 is expressed primaril y in the nervous system. Staining is most intense in the brain and tho racic ganglia and is most likely associated with neuronal elements. NR V1 is more broadly expressed in muscle and excretory tissue and also s hows diffuse distribution in the nervous system. Similar to other spec ies, Drosophila expresses multiple isoforms of Na+,K+-ATPase subunits in a tissue- and cell type-specific pattern. It will now be possible t o use the advantages of Drosophila molecular and classical genetics to investigate the phenotypic consequences of altering Na+,K+-ATPase exp ression in various cell and tissue types.