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Related Concept Videos

The Proteasome01:13

The Proteasome

Eukaryotic cells can degrade proteins through several pathways. One of the most important among these is the ubiquitin-proteasome pathway. It helps the cell eliminate the misfolded, damaged, or unwarranted cytoplasmic proteins in a highly specific manner.
In this pathway, the target proteins are first tagged with small proteins called ubiquitin. This involves participation of a series of enzymes including— E1 (ubiquitin-activating enzyme), E2 (ubiquitin-conjugating enzyme), and E3 (ubiquitin...
The Proteasome02:18

The Proteasome

Eukaryotic cells can degrade proteins through several pathways. One of the most important amongst these is the ubiquitin-proteasome pathway. It helps the cell eliminate the misfolded, damaged, or unwarranted cytoplasmic proteins in a highly specific manner.
In this pathway, the target proteins are first tagged with small proteins called ubiquitin. A series of enzymes carry out the ubiquitination of the target proteins - E1 (ubiquitin-activating enzyme), E2 (ubiquitin-conjugating enzyme), and E3...
The Unfolded Protein Response01:37

The Unfolded Protein Response

The ER is the hub of protein synthesis in a cell. It has robust systems to quality control protein folding and also for degradation of terminally misfolded proteins. Under normal conditions, a small proportion of misfolded proteins that cannot be salvaged need to be transported to the cytoplasm by the ER-associated degradation or ERAD pathways. However, if the ERAD cannot handle the misfolded proteins, the cell activates the unfolded protein response or UPR to adjust the protein folding...
Chronic Pancreatitis II: Pathophysiology01:21

Chronic Pancreatitis II: Pathophysiology

Chronic pancreatitis is a progressive and irreversible inflammation of the pancreas, most often caused by long-term alcohol abuse, but it can also be related to ductal obstruction, smoking, or genetic factors.Chronic pancreatitis occurs when the pancreas is repeatedly exposed to harmful agents like alcohol, smoking, ductal obstruction, or genetic predisposition. These factors lead to the release of toxic metabolites and inflammatory cytokines, sustaining chronic inflammation in the pancreatic...
The Proteasome Structure01:17

The Proteasome Structure

The ubiquitin-proteasome pathway is a well-known mechanism utilized by eukaryotic cells to remove cytoplasmic proteins that are misfolded, damaged, or no longer needed. In this pathway, the protein that needs to be eliminated undergoes a process called ubiquitination, where a chain of ubiquitin molecules is attached to the 48th lysine residue of the target protein. This ubiquitin modification helps the proteasome distinguish between a target protein and a healthy protein.
The proteasome is an...
Export of Misfolded Proteins out of the ER01:32

Export of Misfolded Proteins out of the ER

After folding, the ER assesses the quality of secretory and membrane proteins. The correctly folded proteins are cleared by the calnexin cycle for transport to their final destination, while misfolded proteins are held back in the ER lumen. The ER chaperones attempt to unfold and refold the misfolded proteins but sometimes fail to achieve the correct native conformation. Such terminally misfolded proteins are then exported to the cytosol by ER-associated degradation or ERAD pathway for...

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Related Experiment Video

Updated: Jun 21, 2026

Assessment of Glutamine as a Fuel Source for Alveolar Macrophages Exposed to Chronic Ethanol Using an Extracellular Flux Bioanalyzer
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Assessment of Glutamine as a Fuel Source for Alveolar Macrophages Exposed to Chronic Ethanol Using an Extracellular Flux Bioanalyzer

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Chronic ethanol feeding affects proteasome-interacting proteins.

Marie-Pierre Bousquet-Dubouch1, Sheila Nguen, David Bouyssié

  • 1CNRS, Institut de Pharmacologie et de Biologie Structurale, Toulouse, France. marie-pierre.bousquet@ipbs.fr

Proteomics
|July 18, 2009
PubMed
Summary

Chronic ethanol consumption inhibits proteasome activity by altering proteasome-interacting proteins (PIPs). This study investigated these changes in rat liver, revealing decreased levels of key PIPs crucial for proteasome function.

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Area of Science:

  • Biochemistry
  • Cell Biology
  • Toxicology

Background:

  • Alcoholic liver injury is a significant health concern.
  • Proteasome activity is known to be inhibited in alcoholic liver injury.
  • The precise mechanisms underlying this inhibition require further investigation.

Purpose of the Study:

  • To investigate the impact of chronic ethanol consumption on proteasome complexes and their interacting proteins in rat liver.
  • To identify specific proteasome-interacting proteins (PIPs) affected by ethanol exposure.

Main Methods:

  • Isolation of proteasome complexes from ethanol-fed and control rat livers using non-denaturing centrifugation.
  • Quantitative proteomic analysis using ICAT and MS/MS spectral counting.
  • Validation of protein level changes using Western blot.

Main Results:

  • Significant decrease in several PIPs, including PA28alpha/beta proteasome activator subunits, in ethanol-fed rats.
  • Reduced levels of proteasome-associated deubiquitinases (Rpn11, UCH14, UCHL5) and Ecm29.
  • Alterations in proteasome activator and stabilizer binding, with potential disruption of Rpn13 linkage.

Conclusions:

  • Ethanol metabolism contributes to proteasome inhibition through multiple mechanisms.
  • Altered binding and levels of PIPs, including activators and deubiquitinases, disrupt proteasome function.
  • These molecular changes likely play a role in the pathogenesis of alcoholic liver injury.