title: Dimer formation of subunit G of the yeast V-ATPase.
abstract: The G subunit of the vacuolar ATPase (V-ATPase) is a component of the stalk connecting the V(1) and V(O) sectors of the enzyme and is essential for normal assembly and function. Subunit G (Vma10p) of the yeast V-ATPase was expressed in Escherichia coli as a soluble protein and was purified to homogeneity. The molecular mass of subunit G, determined by Native-polyacrylamide gel electrophoresis, gel filtration analysis and small-angle X-ray scattering, was approximately 28+/-2 kDa, indicating that this protein is dimeric. With a radius of gyration (R(g)) and a maximum size (D(max)) of 2.7+/-0.2 nm and 8.0+/-0.3 nm, respectively, the G-dimer is rather elongated. To understand which region of subunit G is required to mediate dimerization, a G(38-144) form (the carboxyl-terminus) was expressed and purified. G(38-144) is homogeneous, with a molecular mass of approximately 12+/-3 kDa, indicating a monomeric form in solution.
authors.affiliation: Universität des Saarlandes, Fachrichtung 2.5 - Biophysik, D-66421 Homburg, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Armbrüster
authors.forename: Susanne M
authors.initials: SM
authors.lastname: Bailer
authors.forename: Michel H J
authors.initials: MH
authors.lastname: Koch
authors.forename: Jasminka
authors.initials: J
authors.lastname: Godovac-Zimmermann
authors.forename: Gerhard
authors.initials: G
authors.lastname: Grüber
mesh_terms: D001483:Base Sequence; D002850:Chromatography, Gel; D017931:DNA Primers; D019281:Dimerization; D004591:Electrophoresis, Polyacrylamide Gel; D008970:Molecular Weight; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D012542:Scattering, Radiation; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D025262:Vacuolar Proton-Translocating ATPases / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D017931:DNA Primers; D011994:Recombinant Proteins; D025262:Vacuolar Proton-Translocating ATPases