title: Mouse proton pump ATPase C subunit isoforms (C2-a and C2-b) specifically expressed in kidney and lung.
abstract: The vacuolar-type H+-ATPases (V-ATPases) are multimeric proton pumps involved in a wide variety of physiological processes. We have identified two alternative splicing variants of C2 subunit isoforms: C2-a, a lung-specific isoform containing a 46-amino acid insertion, and C2-b, a kidney-specific isoform without the insert. Immunohistochemistry with isoform-specific antibodies revealed that V-ATPase with C2-a is localized specifically in lamellar bodies of type II alveolar cells, whereas the C2-b isoform is found in the plasma membranes of renal alpha and beta intercalated cells. Immunoprecipitation combined with immunohistological analysis revealed that C2-b together with other kidney-specific isoforms was selectively assembled to form a unique proton pump in intercalated cells. Furthermore, a chimeric yeast V-ATPase with mouse the C2-a or C2-b isoform showed a lower Km(ATP) and lower proton transport activity than that with C1 or Vma5p (yeast C subunit). These results suggest that V-ATPases with the C2-a and C2-b isoform are involved in luminal acidification of lamellar bodies and regulation of the renal acid-base balance, respectively.
authors.affiliation: Division of Biological Sciences, Institute of Scientific and Industrial Research, Osaka University, Osaka 567-0047, Japan.
authors.forename: Ge-Hong
authors.initials: GH
authors.lastname: Sun-Wada
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Murata
authors.forename: Miwako
authors.initials: M
authors.lastname: Namba
authors.forename: Akitsugu
authors.initials: A
authors.lastname: Yamamoto
authors.forename: Yoh
authors.initials: Y
authors.lastname: Wada
authors.forename: Masamitsu
authors.initials: M
authors.lastname: Futai
mesh_terms: D000136:Acid-Base Equilibrium; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D015152:Blotting, Northern; D002462:Cell Membrane / Q000201:enzymology; D017124:Conserved Sequence; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D007163:Immunosorbent Techniques; D017403:In Situ Hybridization; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics / Q000502:physiology; D007668:Kidney / Q000201:enzymology* / Q000502:physiology; D007700:Kinetics; D008168:Lung / Q000201:enzymology*; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D009928:Organ Specificity; D017494:Proton Pumps / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D011650:Pulmonary Alveoli / Q000201:enzymology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D025262:Vacuolar Proton-Translocating ATPases / Q000737:chemistry / Q000235:genetics* / Q000502:physiology
chemical_list: D007527:Isoenzymes; D017494:Proton Pumps; C480044:Atp6v1c1 protein, mouse; C503862:Atp6v1c2 protein, mouse; D025262:Vacuolar Proton-Translocating ATPases