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The molecular mechanisms underlying BiP-mediated gating of the Sec61 translocon of the endoplasmic reticulum

The Sec61 translocon of the endoplasmic reticulum membrane forms an aqueous pore that is gated by the lumenal Hsp70 chaperone BiP. We have explored the molecular mechanisms governing BiP-mediated gating activity, including the coupling between gating and the BiP ATPase cycle, and the involvement of...

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Detalles Bibliográficos
Autores principales: Alder, Nathan N., Shen, Ying, Brodsky, Jeffrey L., Hendershot, Linda M., Johnson, Arthur E.
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 2005
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2171714/
https://www.ncbi.nlm.nih.gov/pubmed/15684029
http://dx.doi.org/10.1083/jcb.200409174
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author Alder, Nathan N.
Shen, Ying
Brodsky, Jeffrey L.
Hendershot, Linda M.
Johnson, Arthur E.
author_facet Alder, Nathan N.
Shen, Ying
Brodsky, Jeffrey L.
Hendershot, Linda M.
Johnson, Arthur E.
author_sort Alder, Nathan N.
collection PubMed
description The Sec61 translocon of the endoplasmic reticulum membrane forms an aqueous pore that is gated by the lumenal Hsp70 chaperone BiP. We have explored the molecular mechanisms governing BiP-mediated gating activity, including the coupling between gating and the BiP ATPase cycle, and the involvement of the substrate-binding and J domain–binding regions of BiP. Translocon gating was assayed by measuring the collisional quenching of fluorescent probes incorporated into nascent chains of translocation intermediates engaged with microsomes containing various BiP mutants and BiP substrate. Our results indicate that BiP must assume the ADP-bound conformation to seal the translocon, and that the reopening of the pore requires an ATP binding–induced conformational change. Further, pore closure requires functional interactions between both the substrate-binding region and the J domain–binding region of BiP and membrane proteins. The mechanism by which BiP mediates translocon pore closure and opening is therefore similar to that in which Hsp70 chaperones associate with and dissociate from substrates.
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spelling pubmed-21717142008-03-05 The molecular mechanisms underlying BiP-mediated gating of the Sec61 translocon of the endoplasmic reticulum Alder, Nathan N. Shen, Ying Brodsky, Jeffrey L. Hendershot, Linda M. Johnson, Arthur E. J Cell Biol Research Articles The Sec61 translocon of the endoplasmic reticulum membrane forms an aqueous pore that is gated by the lumenal Hsp70 chaperone BiP. We have explored the molecular mechanisms governing BiP-mediated gating activity, including the coupling between gating and the BiP ATPase cycle, and the involvement of the substrate-binding and J domain–binding regions of BiP. Translocon gating was assayed by measuring the collisional quenching of fluorescent probes incorporated into nascent chains of translocation intermediates engaged with microsomes containing various BiP mutants and BiP substrate. Our results indicate that BiP must assume the ADP-bound conformation to seal the translocon, and that the reopening of the pore requires an ATP binding–induced conformational change. Further, pore closure requires functional interactions between both the substrate-binding region and the J domain–binding region of BiP and membrane proteins. The mechanism by which BiP mediates translocon pore closure and opening is therefore similar to that in which Hsp70 chaperones associate with and dissociate from substrates. The Rockefeller University Press 2005-01-31 /pmc/articles/PMC2171714/ /pubmed/15684029 http://dx.doi.org/10.1083/jcb.200409174 Text en Copyright © 2005, The Rockefeller University Press This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/).
spellingShingle Research Articles
Alder, Nathan N.
Shen, Ying
Brodsky, Jeffrey L.
Hendershot, Linda M.
Johnson, Arthur E.
The molecular mechanisms underlying BiP-mediated gating of the Sec61 translocon of the endoplasmic reticulum
title The molecular mechanisms underlying BiP-mediated gating of the Sec61 translocon of the endoplasmic reticulum
title_full The molecular mechanisms underlying BiP-mediated gating of the Sec61 translocon of the endoplasmic reticulum
title_fullStr The molecular mechanisms underlying BiP-mediated gating of the Sec61 translocon of the endoplasmic reticulum
title_full_unstemmed The molecular mechanisms underlying BiP-mediated gating of the Sec61 translocon of the endoplasmic reticulum
title_short The molecular mechanisms underlying BiP-mediated gating of the Sec61 translocon of the endoplasmic reticulum
title_sort molecular mechanisms underlying bip-mediated gating of the sec61 translocon of the endoplasmic reticulum
topic Research Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2171714/
https://www.ncbi.nlm.nih.gov/pubmed/15684029
http://dx.doi.org/10.1083/jcb.200409174
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