High impact information on nrv2

• Our genetic analysis using a sinuous null mutation suggests that sinuous functions in the same pathway as the septate junction genes neurexin and scribble, but that nervana 2, convoluted, varicose, and cystic have functions not shared by sinuous [1].
• Spectrin has been proposed to function as a sorting machine that concentrates interacting proteins such as the Na,K ATPase within specialized plasma membrane domains of polarized cells [2].
• Drosophila beta spectrin functions independently of alpha spectrin to polarize the Na,K ATPase in epithelial cells [2].
• Expression is controlled with transcriptional regulatory elements present in the 5' flanking DNA of the Drosophila Na(+), K(+)-ATPase beta-subunit gene Nervana2 (Nrv2) [3].
• A nervous system-specific glycoprotein antigen from adult Drosophila heads, designated Nervana (Nrv), has been purified on the basis of reactivity of its carbohydrate epitope(s) with anti-horseradish peroxidase (HRP) antibodies that are specific markers for Drosophila neurons [4].

Biological context of nrv2

• The heterodimeric Na,K-ATPase has been implicated in vertebrate and invertebrate epithelial cell junctions, morphogenesis and oncogenesis, but the mechanisms involved are unclear [5].
• The genomic DNA positioned in the 5' flanking region of each Nrv gene has also been tested for tissue-specific transcriptional regulatory activity [6].
• P-element transformation vectors were constructed, which contained either 7.7kb of Nrv2 or 3.5kb Nrv1 5' flanking DNA driving expression of a lacZ reporter gene [6].
• The high-temperature rescue of homozygous 0462 flies appeared to result primarily from improved Na,K-ATPase expression rather than an increase in the rate of ion transport per Na,K-ATPase molecule [7].
• The Drosophila Na,K-ATPase (or sodium pump) alpha-subunit gene was found to contain 10 exons and span approx. 25 kb [7].

Anatomical context of nrv2

• ATPalpha and nrv2 mutations also disrupt stable formation of septate junctions, structures with some functional and molecular similarities to vertebrate tight junctions [8].
• In this study we have isolated a new Drosophila Na+,K+-ATPase alpha subunit cDNA clone (PSalpha; GenBank accession no. AF044974) and demonstrate expression of functional Na+,K+-ATPase activity when PSalpha mRNA is coinjected into Xenopus oocytes along with any of the three different Nrv mRNAs [9].
• A Na+/K+-ATPase was also present in the basolateral membrane of the Malpighian tubules [10].
• During all phases of oogenesis, Na,K-ATPase were found in apical and lateral follicle-cell membranes and, during rapid follicle growth (beginning with stage 10), also in nurse-cell membranes and in the oolemma [11].
• Na,K-ATPase and V-ATPase in ovarian follicles of Drosophila melanogaster [11].

Associations of nrv2 with chemical compounds

• We have previously purified and characterized a nervous system-specific glycoprotein antigen from adult Drosophila heads, designated Nervana [nerve antigen (NRV)] and identified two separate genes coding for three different proteins [9].
• Glutamate 779, an intramembrane carboxyl, is essential for monovalent cation binding by the Na,K-ATPase [12].
• Incubation of purified renal Na,K-ATPase with the fluorescent carboxyl-selective reagent, 4-(diazomethyl)-7-(diethylamino)- coumarin (DEAC), results in enzyme inactivation via disruption of the monovalent cation binding sites and loss of K+ and Na+ binding capacity [12].
• We suggest that an apical vacuolar-type H+-ATPase and a basolateral Na+/K+-ATPase are both stimulated by cyclic AMP [10].

Other interactions of nrv2

• Only 3kb of DNA separate the 3' end of Nrv2 from Nrv1 [6].

Analytical, diagnostic and therapeutic context of nrv2

• Immunoaffinity-purified Nrv is associated with a protein (M(r) 100,000) recognized on Western blots by anti-ATPase alpha-subunit mAb [4].

References