mBet3p is required for homotypic COPII vesicle tethering in mammalian cells

Sidney Yu, Ayano Satoh, Marc Pypaert, Karl Mullen, Jesse C. Hay, Susan Ferro-Novick

Research output: Contribution to journalArticle

61 Citations (Scopus)

Abstract

TRAPPI is a large complex that mediates the tethering of COPII vesicles to the Golgi (heterotypic tethering) in the yeast Saccharomyces cerevisiae. In mammalian cells, COPII vesicles derived from the transitional endoplasmic reticulum (tER) do not tether directly to the Golgi, instead, they appear to tether to each other (homotypic tethering) to form vesicular tubular clusters (VTCs). We show that mammalian Bet3p (mBet3p), which is the most highly conserved TRAPP subunit, resides on the tER and adjacent VTCs. The inactivation of mBet3p results in the accumulation of cargo in membranes that colocalize with the COPII coat. Furthermore, using an assay that reconstitutes VTC biogenesis in vitro, we demonstrate that mBet3p is required for the tethering and fusion of COPII vesicles to each other. Consistent with the proposal that mBet3p is required for VTC biogenesis, we find that ERGIC-53 (VTC marker) and Golgi architecture are disrupted in siRNA-treated mBet3p-depleted cells. These findings imply that the TRAPPI complex is essential for VTC biogenesis.

Original languageEnglish
Pages (from-to)359-368
Number of pages10
JournalJournal of Cell Biology
Volume174
Issue number3
DOIs
Publication statusPublished - Jul 31 2006
Externally publishedYes

ASJC Scopus subject areas

  • Cell Biology

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