title: Three subunit a isoforms of mouse vacuolar H(+)-ATPase. Preferential expression of the a3 isoform during osteoclast differentiation.
abstract: Vacuolar H(+)-ATPase (V-ATPase) is a multi-subunit enzyme with a membrane peripheral catalytic (V(1)) and an intrinsic (V(o)) sector. We have identified three cDNA clones coding for isoforms of mouse V(o) subunit a (a1, a2, and a3). They exhibit 48-52% identity with each other and high similarity to subunit a of other species. The a1 isoform was mainly expressed in brain and liver. The a2 isoform was observed in heart and kidney in addition to brain and liver. Transcripts for the a3 isoform were strongly expressed in heart and liver. The a3 isoform was induced during osteoclast differentiation, and localized in the plasma membrane and cytoplasmic filamentous structures. In contrast to a3, the a1 isoform was constitutively expressed and localized in the cytoplasmic endomembrane compartments of the same cells. These findings suggest that the a3 isoform is a component of the plasma membrane V-ATPase essential for bone resorption.
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: Toyomura
authors.forename: T
authors.initials: T
authors.lastname: Oka
authors.forename: C
authors.initials: C
authors.lastname: Yamaguchi
authors.forename: Y
authors.initials: Y
authors.lastname: Wada
authors.forename: M
authors.initials: M
authors.lastname: Futai
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002451:Cell Compartmentation; D002454:Cell Differentiation; D002462:Cell Membrane / Q000201:enzymology; D018076:DNA, Complementary; D005455:Fluorescent Antibody Technique; D018507:Gene Expression Regulation, Developmental; D051379:Mice; D008870:Microtubules / Q000737:chemistry; D008969:Molecular Sequence Data; D015388:Organelles / Q000201:enzymology; D010010:Osteoclasts / Q000166:cytology / Q000201:enzymology*; D020033:Protein Isoforms / Q000235:genetics / Q000302:isolation & purification; D006180:Proton-Translocating ATPases / Q000235:genetics* / Q000302:isolation & purification*; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution; D025262:Vacuolar Proton-Translocating ATPases; D014617:Vacuoles / Q000201:enzymology*
chemical_list: D018076:DNA, Complementary; D020033:Protein Isoforms; D025262:Vacuolar Proton-Translocating ATPases; D006180:Proton-Translocating ATPases