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The export and 

degradation of misfolded ER proteins. Misfolded soluble proteins in the ER lumen are recognized and targeted to a translocator complex in the ER membrane. They first interact in the ER lumen with chaperones, disulfide isomerases, and lectins. The chaperones maintain the misfolded protein in an unfolded conformation and prevent their aggregation. The disulfide isomerases reduce disulfide bonds to fully unfold the protein. The lectins selectively recognize trimmed N-linked oligosaccharides that are generated when a protein spends too long in the ER. The lectins have binding sites on a membrane-embedded protein translocator built around an E3 ubiquitin ligase. The unfolded protein is then exported into the cytosol through the translocator. The E3 ubiquitin ligase ubiquitylates the unfolded protein as it emerges on the cytosolic side of the translocator. The ubiquitin prevents backsliding of the protein into the ER and provides a molecular handle for an AAA-ATPase that completes the extraction reaction. The unfolded protein is then de-glycosylated and degraded in proteasomes. Misfolded membrane proteins follow a similar pathway but are thought to engage the translocator sideways within the lipid bilayer. Multiple translocator complexes containing different E3 ubiquitin ligases reside in the ER. They are thought to handle different subsets of proteins that are misfolded in different ways.