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gp78 functions downstream of Hrd1 to promote degradation of misfolded proteins of the endoplasmic reticulum
Eukaryotic cells eliminate misfolded proteins from the endoplasmic reticulum (ER) via a conserved process termed ER-associated degradation (ERAD). Central regulators of the ERAD system are membrane-bound ubiquitin ligases, which are thought to channel misfolded proteins through the ER membrane durin...
Autores principales: | , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
The American Society for Cell Biology
2015
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4666138/ https://www.ncbi.nlm.nih.gov/pubmed/26424800 http://dx.doi.org/10.1091/mbc.E15-06-0354 |
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author | Zhang, Ting Xu, Yue Liu, Yanfen Ye, Yihong |
author_facet | Zhang, Ting Xu, Yue Liu, Yanfen Ye, Yihong |
author_sort | Zhang, Ting |
collection | PubMed |
description | Eukaryotic cells eliminate misfolded proteins from the endoplasmic reticulum (ER) via a conserved process termed ER-associated degradation (ERAD). Central regulators of the ERAD system are membrane-bound ubiquitin ligases, which are thought to channel misfolded proteins through the ER membrane during retrotranslocation. Hrd1 and gp78 are mammalian ubiquitin ligases homologous to Hrd1p, an ubiquitin ligase essential for ERAD in Saccharomyces cerevisiae. However, the functional relevance of these proteins to Hrd1p is unclear. In this paper, we characterize the gp78-containing ubiquitin ligase complex and define its functional interplay with Hrd1 using biochemical and recently developed CRISPR-based genetic tools. Our data show that transient inactivation of the gp78 complex by short hairpin RNA–mediated gene silencing causes significant stabilization of both luminal and membrane ERAD substrates, but unlike Hrd1, which plays an essential role in retrotranslocation and ubiquitination of these ERAD substrates, knockdown of gp78 does not affect either of these processes. Instead, gp78 appears to act downstream of Hrd1 to promote ERAD via cooperation with the BAG6 chaperone complex. We conclude that the Hrd1 complex forms an essential retrotranslocation module that is evolutionarily conserved, but the mammalian ERAD system uses additional ubiquitin ligases to assist Hrd1 during retrotranslocation. |
format | Online Article Text |
id | pubmed-4666138 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2015 |
publisher | The American Society for Cell Biology |
record_format | MEDLINE/PubMed |
spelling | pubmed-46661382016-02-16 gp78 functions downstream of Hrd1 to promote degradation of misfolded proteins of the endoplasmic reticulum Zhang, Ting Xu, Yue Liu, Yanfen Ye, Yihong Mol Biol Cell Articles Eukaryotic cells eliminate misfolded proteins from the endoplasmic reticulum (ER) via a conserved process termed ER-associated degradation (ERAD). Central regulators of the ERAD system are membrane-bound ubiquitin ligases, which are thought to channel misfolded proteins through the ER membrane during retrotranslocation. Hrd1 and gp78 are mammalian ubiquitin ligases homologous to Hrd1p, an ubiquitin ligase essential for ERAD in Saccharomyces cerevisiae. However, the functional relevance of these proteins to Hrd1p is unclear. In this paper, we characterize the gp78-containing ubiquitin ligase complex and define its functional interplay with Hrd1 using biochemical and recently developed CRISPR-based genetic tools. Our data show that transient inactivation of the gp78 complex by short hairpin RNA–mediated gene silencing causes significant stabilization of both luminal and membrane ERAD substrates, but unlike Hrd1, which plays an essential role in retrotranslocation and ubiquitination of these ERAD substrates, knockdown of gp78 does not affect either of these processes. Instead, gp78 appears to act downstream of Hrd1 to promote ERAD via cooperation with the BAG6 chaperone complex. We conclude that the Hrd1 complex forms an essential retrotranslocation module that is evolutionarily conserved, but the mammalian ERAD system uses additional ubiquitin ligases to assist Hrd1 during retrotranslocation. The American Society for Cell Biology 2015-12-01 /pmc/articles/PMC4666138/ /pubmed/26424800 http://dx.doi.org/10.1091/mbc.E15-06-0354 Text en © 2015 Zhang et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0). “ASCB®,” “The American Society for Cell Biology®,” and “Molecular Biology of the Cell®” are registered trademarks of The American Society for Cell Biology. |
spellingShingle | Articles Zhang, Ting Xu, Yue Liu, Yanfen Ye, Yihong gp78 functions downstream of Hrd1 to promote degradation of misfolded proteins of the endoplasmic reticulum |
title | gp78 functions downstream of Hrd1 to promote degradation of misfolded proteins of the endoplasmic reticulum |
title_full | gp78 functions downstream of Hrd1 to promote degradation of misfolded proteins of the endoplasmic reticulum |
title_fullStr | gp78 functions downstream of Hrd1 to promote degradation of misfolded proteins of the endoplasmic reticulum |
title_full_unstemmed | gp78 functions downstream of Hrd1 to promote degradation of misfolded proteins of the endoplasmic reticulum |
title_short | gp78 functions downstream of Hrd1 to promote degradation of misfolded proteins of the endoplasmic reticulum |
title_sort | gp78 functions downstream of hrd1 to promote degradation of misfolded proteins of the endoplasmic reticulum |
topic | Articles |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4666138/ https://www.ncbi.nlm.nih.gov/pubmed/26424800 http://dx.doi.org/10.1091/mbc.E15-06-0354 |
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