The organization of engaged and quiescent translocons in the endoplasmic reticulum of mammalian cells

Erik L. Snapp, Gretchen A. Reinhart, Brigitte A. Bogert, Jennifer Lippincott-Schwartz, Ramanujan S. Hegde

Research output: Contribution to journalArticle

55 Scopus citations

Abstract

Protein translocons of the mammalian endoplasmic reticulum are composed of numerous functional components whose organization during different stages of the transport cycle in vivo remains poorly understood. We have developed generally applicable methods based on fluorescence resonance energy transfer (FRET) to probe the relative proximities of endogenously expressed translocon components in cells. Examination of substrate-engaged translocons revealed oligomeric assemblies of the Sec61 complex that were associated to varying degrees with other essential components including the signal recognition particle receptor TRAM and the TRAP complex. Remarkably, these components not only remained assembled but also had a similar, yet distinguishable, organization both during and after nascent chain translocation. The persistence of preassembled and complete translocons between successive rounds of transport may facilitate highly efficient translocation in vivo despite temporal constraints imposed by ongoing translation and a crowded cellular environment.

Original languageEnglish (US)
Pages (from-to)997-1007
Number of pages11
JournalJournal of Cell Biology
Volume164
Issue number7
DOIs
StatePublished - Mar 29 2004

Keywords

  • FRET
  • Protein translocation
  • Sec61
  • TRAM
  • TRAP

ASJC Scopus subject areas

  • Cell Biology

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    Snapp, E. L., Reinhart, G. A., Bogert, B. A., Lippincott-Schwartz, J., & Hegde, R. S. (2004). The organization of engaged and quiescent translocons in the endoplasmic reticulum of mammalian cells. Journal of Cell Biology, 164(7), 997-1007. https://doi.org/10.1083/jcb.200312079