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 language | English (US) |
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Pages (from-to) | 997-1007 |
Number of pages | 11 |
Journal | Journal of Cell Biology |
Volume | 164 |
Issue number | 7 |
DOIs | |
State | Published - Mar 29 2004 |
Externally published | Yes |
Keywords
- FRET
- Protein translocation
- Sec61
- TRAM
- TRAP
ASJC Scopus subject areas
- Cell Biology