title: a4, a unique kidney-specific isoform of mouse vacuolar H+-ATPase subunit a.
abstract: The vacuolar-type H+ -ATPase (V-ATPase) translocates protons across membranes. Here, we have identified a mouse cDNA coding for a fourth isoform (a4) of the membrane sector subunit a of V-ATPase. This isoform was specifically expressed in kidney, but not in the heart, brain, spleen, lung, liver, muscle, or testis. Immunoprecipitation experiments, together with sequence similarities for other isoforms (a1, a2, and a3), indicate that the a4 isoform is a component of V-ATPase. Moreover, histochemical studies show that a4 is localized in the apical and basolateral plasma membranes of cortical alpha- and beta-intercalated cells, respectively. These results suggest that the V-ATPase, with the a4 isoform, is important for renal acid/base homeostasis.
authors.affiliation: Division of Biological Sciences, Institute of Scientific and Industrial Research, Osaka University, Core Research for Evolutional Science and Technology (CREST) of the Japan Science and Technology Corporation, Osaka 567-0047, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Oka
authors.forename: Y
authors.initials: Y
authors.lastname: Murata
authors.forename: M
authors.initials: M
authors.lastname: Namba
authors.forename: T
authors.initials: T
authors.lastname: Yoshimizu
authors.forename: T
authors.initials: T
authors.lastname: Toyomura
authors.forename: A
authors.initials: A
authors.lastname: Yamamoto
authors.forename: G H
authors.initials: GH
authors.lastname: Sun-Wada
authors.forename: N
authors.initials: N
authors.lastname: Hamasaki
authors.forename: Y
authors.initials: Y
authors.lastname: Wada
authors.forename: M
authors.initials: M
authors.lastname: Futai
mesh_terms: D000136:Acid-Base Equilibrium; D000595:Amino Acid Sequence; D000818:Animals; D002462:Cell Membrane / Q000201:enzymology; D016764:Cell Polarity; D015723:Gene Library; D007668:Kidney / Q000201:enzymology*; D007672:Kidney Cortex / Q000166:cytology / Q000201:enzymology; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000201:enzymology; D051379:Mice; D008969:Molecular Sequence Data; D020033:Protein Isoforms / Q000235:genetics / Q000302:isolation & purification; D021122:Protein Subunits; D017386:Sequence Homology, Amino Acid; D025262:Vacuolar Proton-Translocating ATPases / Q000235:genetics / Q000302:isolation & purification*
chemical_list: D020033:Protein Isoforms; D021122:Protein Subunits; D025262:Vacuolar Proton-Translocating ATPases