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Molecular characterization of a pyrophosphate-energized proton pump

The H$ sp+$-translocating inorganic pyrophosphatase from vacuolar membranes of red beet storage roots (Beta vulgaris L.) was purified after solubilization in Triton X-100 through a combination of anion-exchange and size exclusion chromatographies. SDS-PAGE showed strong correlation between a 67 kDa polypeptide and pyrophosphatase activity. Radiation-inactivation studies of the H$ sp+$-PPase indicate a functional size of 91 kDa for hydrolysis and 320 kDa for H$ sp+$ translocation, suggesting an oligomeric structure for the holoenzyme. Affinity purified antibodies were used to screen cDNA libraries of Arabidopsis thaliana yielding clones which contained sequences matching amino acid sequences obtained from tryptic fragments of the 67 kDa hydrolytic subunit. The predicted protein is highly hydrophobic with a molecular size of 81 kDa. Southern analyses show a single copy for the H$ sp+$-PPase in Arabidopsis. The lack of sequence identities between the H$ sp+$-PPase and other known proteins implies a novel class of ion translocases.

Identiferoai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.39460
Date January 1992
CreatorsSarafian, Vahé
PublisherMcGill University
Source SetsLibrary and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada
LanguageEnglish
Detected LanguageEnglish
TypeElectronic Thesis or Dissertation
Formatapplication/pdf
CoverageDoctor of Philosophy (Department of Biology.)
RightsAll items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated.
Relationalephsysno: 001317720, proquestno: NN80465, Theses scanned by UMI/ProQuest.

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