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The Roles of the Voa Subunit of the Vacuolar H+-ATPase in Dense-core Vesicle Acidification, Transmitter Uptake and Storage

The Vo sector of the vacuolar H+-ATPase is a multi-subunit complex that forms a proteolipid pore. The largest subunit in this complex is the a subunit which has four isoforms (a1-a4). The isoform(s) critical for secretory vesicle acidification has yet to be identified. Using a cell line derived from rat pheochromocytoma in which Voa1 and/or Voa2 had been down-regulated this study revealed that Voa1, and to a lesser extent, Voa2 are critical for acidifying dense-core vesicles (DCVs). The acidification defects resulting from down-regulation of Voa1 and Voa1/ Voa2 were suppressed by the expression of knockdown-resistant Voa1. Defects in DCV acidification resulted in reductions in their transmitter uptake and storage. Lastly, Ca2+-dependent peptide secretion appeared normal in Voa1 and Voa1/ Voa2 knockdown cells. . This study demonstrated that Voa1 and Voa2 cooperatively regulate dense-core vesicle acidification as well as transmitter uptake/storage, while they may not be critical for dense-core vesicle exocytosis.

Identiferoai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/31433
Date20 December 2011
CreatorsSaw, Ner Mu Nar
ContributorsSugita, Shuzo
Source SetsUniversity of Toronto
Languageen_ca
Detected LanguageEnglish
TypeThesis

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