Specific transmembrane segments are selectively delayed at the ER translocon during opsin biogenesis
- 14 April 2008
- journal article
- Published by Portland Press Ltd. in Biochemical Journal
- Vol. 411 (3), 495-506
- https://doi.org/10.1042/bj20071597
Abstract
A site-specific cross-linking approach was used to study the integration of TM (transmembrane) segments 4–7 of the polytopic membrane protein, opsin, at the ER (endoplasmic reticulum). We found that although TM4 exits the ER translocon rapidly, TM segments 5, 6 and 7 are all retained at the translocon until opsin biosynthesis is terminated. Furthermore, although artificial extension of the nascent chain is not sufficient to release the C-terminal region of opsin from the translocon, substitution of the native TM segment 7 with a more hydrophobic TM segment results in its rapid lateral exit into the lipid bilayer. We conclude that the intrinsic properties of a TM segment determine the timing of its membrane integration rather than its relative location within the polypeptide chain. A pronounced and prolonged association of opsin TM5 with the translocon-associated component PAT-10 was also observed, suggesting that PAT-10 may facilitate the assembly of distinct opsin subdomains during membrane integration. The results of the present study strongly support a model in which the ER translocon co-ordinates the integration of selected TM segments in response to the specific requirements of the precursor being synthesized.This publication has 39 references indexed in Scilit:
- A novel tripartite motif involved in aquaporin topogenesis, monomer folding and tetramerizationNature Structural & Molecular Biology, 2007
- The Plug Domain of the SecY Protein Stabilizes the Closed State of the Translocation Channel and Maintains a Membrane SealMolecular Cell, 2007
- Domain Interdependence in the Biosynthetic Assembly of CFTRJournal of Molecular Biology, 2007
- The Plug Domain of Yeast Sec61p Is Important for Efficient Protein Translocation, but Is Not Essential for Cell ViabilityMolecular Biology of the Cell, 2006
- Active and passive displacement of transmembrane domains both occur during opsin biogenesis at the Sec61 transloconJournal of Cell Science, 2006
- G Protein–Coupled Receptor RhodopsinAnnual Review of Biochemistry, 2006
- PROTEIN TRANSLOCATION BY THE SEC61/SECY CHANNELAnnual Review of Cell and Developmental Biology, 2005
- Architecture of the Ribosome–Channel Complex Derived from Native MembranesJournal of Molecular Biology, 2005
- X-ray structure of a protein-conducting channelNature, 2003
- The Cotranslational Integration of Membrane Proteins into the Phospholipid Bilayer Is a Multistep ProcessCell, 1996