title: Vma9p need not be associated with the yeast V-ATPase for fully-coupled proton pumping activity in vitro.
abstract: Vacuolar-type ATPases (V-ATPases) acidify numerous intracellular compartments in all eukaryotic cells and are responsible for extracellular acidification in some specialized cells. V-ATPases are large macromolecular complexes with at least 15 different subunits, some of which are found in multiple copies. The main roles of all V-ATPase subunits have been established except for the e subunit, encoded by the gene VMA9 in Saccharomyces cerevisiae, and the Ac45 subunit, which is not found in the S. cerevisiae enzyme. Here we demonstrate that when the S. cerevisiae V-ATPase is solubilized with the detergent dodecylmaltoside (DDM), Vma9p is removed. We further demonstrate that after Vma9p has been removed by detergent the purified enzyme is still able to perform fully-coupled ATP-dependent proton pumping. This observation shows that Vma9p is not necessary in vitro for this principal activity of the V-ATPase.
authors.affiliation: Molecular Structure and Function Program, The Hospital for Sick Children Research Institute , Toronto, Ontario M5G 1X8, Canada.
authors.forename: Stephanie A
authors.initials: SA
authors.lastname: Bueler
authors.forename: John L
authors.initials: JL
authors.lastname: Rubinstein
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D005960:Glucosides / Q000378:metabolism; D006868:Hydrolysis; D017494:Proton Pumps / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D012995:Solubility; D025262:Vacuolar Proton-Translocating ATPases / Q000378:metabolism*
chemical_list: D005960:Glucosides; D017494:Proton Pumps; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; C040358:dodecyl maltoside; D000255:Adenosine Triphosphate; C486463:VMA9 protein, S cerevisiae; D025262:Vacuolar Proton-Translocating ATPases