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gp78 functions downstream of Hrd1 to promote degradation of misfolded proteins of the endoplasmic reticulum
- Source :
- Molecular Biology of the Cell
- Publication Year :
- 2015
- Publisher :
- American Society for Cell Biology (ASCB), 2015.
-
Abstract
- The functional relationship between mammalian ubiquitin ligase gp78 and Hrd1 was studied. Hrd1 is one of the essential retrotranslocation regulators conserved in yeast and mammalian cells, whereas gp78 serves an assisting role downstream of Hrd1 and possibly other ubiquitin ligases in mammalian cells.<br />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.
- Subjects :
- Protein Folding
Ubiquitin-Protein Ligases
macromolecular substances
Plasma protein binding
Endoplasmic-reticulum-associated protein degradation
Endoplasmic Reticulum
Ubiquitin
Humans
Molecular Biology
biology
Endoplasmic reticulum
Ubiquitination
Articles
Endoplasmic Reticulum-Associated Degradation
Cell Biology
Ubiquitin ligase
Cell biology
Receptors, Autocrine Motility Factor
HEK293 Cells
Biochemistry
Membrane Trafficking
Ubiquitin ligase complex
Proteolysis
biology.protein
Chaperone complex
Molecular Chaperones
Protein Binding
Subjects
Details
- ISSN :
- 19394586 and 10591524
- Volume :
- 26
- Database :
- OpenAIRE
- Journal :
- Molecular Biology of the Cell
- Accession number :
- edsair.doi.dedup.....5af439a676e8c02d265fae36b1917d68