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Endoplasmic reticulum (ER)-associated protein degradation (ERAD) eliminates misfolded or unassembled proteins from the ER. ERAD targets are selected by a quality control system within the ER lumen and are ultimately destroyed by the cytoplasmic ubiquitin-proteasome system (UPS). The spatial separation between substrate selection and degradation in ERAD(More)
To maintain protein homeostasis in secretory compartments, eukaryotic cells harbor a quality control system that monitors protein folding and protein complex assembly in the endoplasmic reticulum (ER). Proteins that do not fold properly or integrate into cognate complexes are degraded by ER-associated degradation (ERAD) involving retrotranslocation to the(More)
Protein quality control in the endoplasmic reticulum is of central importance for cellular homeostasis in eukaryotes. Crucial for this process is the HRD-ubiquitin ligase (HMG-CoA reductase degradation), which singles out terminally misfolded proteins and routes them for degradation to cytoplasmic 26S-proteasomes. Certain functions of this enzyme complex(More)
As proteins travel through the endoplasmic reticulum (ER), a quality-control system retains newly synthesized polypeptides and supports their maturation. Only properly folded proteins are released to their designated destinations. Proteins that cannot mature are left to accumulate, impairing the function of the ER. To maintain homeostasis, the(More)
A quality-control system surveys the lumen of the endoplasmic reticulum for terminally misfolded proteins. Polypeptides singled out by this system are ultimately degraded by the cytosolic ubiquitin-proteasome pathway. Key components of both the endoplasmic reticulum quality-control system and the degradation machinery have been identified, but a connection(More)
The endoplasmic reticulum (ER) is the eukaryotic organelle where most secretory proteins are folded for subsequent delivery to their site of action. Proper folding of newly synthesized proteins is monitored by a stringent ER quality control system. This system recognizes misfolded or unassembled proteins and prevents them from reaching their final(More)
The human cytomegalovirus-encoded glycoprotein US2 catalyzes proteasomal degradation of Class I major histocompatibility complex (MHC) heavy chains (HCs) through dislocation of the latter from the endoplasmic reticulum (ER) to the cytosol. During this process, the Class I MHC HCs are deglycosylated by an N-glycanase-type activity. siRNA molecules designed(More)
Proteasomes are soluble, but can also be found in association with subcellular organelles. Adaptors capable of mediating interactions between proteasomes and intracellular organelles have not yet been identified, although they might exist. Although most proteasomal substrates are soluble, some membrane-bound proteins are also degraded by the proteasome.(More)
Successful maturation determines the intracellular fate of secretory and membrane proteins in the endoplasmic reticulum (ER). Failure of proteins to fold or assemble properly can lead to their retention in the ER and redirects them to the cytosol for degradation by the proteasome. Proteasome inhibitors can yield deglycosylated cytoplasmic intermediates that(More)
The mammalian endoplasmic reticulum (ER)-to-cytosol degradation pathway for disposal of misfolded proteins is an attractive target for therapeutic intervention in diseases that are characterized by impaired protein degradation. The ability to do so is hampered by the small number of specific inhibitors available and by our limited understanding of the(More)