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Related Concept Videos

The Proteasome Structure01:17

The Proteasome Structure

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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...
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The Proteasome02:18

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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.
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The Proteasome01:13

The Proteasome

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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.
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The Proteasome02:18

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Regulated Protein Degradation02:58

Regulated Protein Degradation

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It is vital to regulate the activity of enzymatic as well as non-enzymatic proteins inside the cell. This can be achieved either through creating a balance between their rate of synthesis and degradation or regulating the intrinsic activity of the protein. Both these regulation mechanisms play an essential role in the normal functioning of cells.
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Lysosomes01:31

Lysosomes

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Lysosomes are membrane-enclosed spherical sacs derived from the Golgi apparatus. The most important function of the lysosome is degrading macromolecules and biological polymers that are released during membrane trafficking events such as the secretory, endocytic, autophagic, and phagocytic pathways. The degradation is carried out by several hydrolytic enzymes active in an acidic environment of the lysosomal lumen. These acid hydrolases are involved in cellular processes such as cell signaling,...
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Assaying Proteasomal Degradation in a Cell-free System in Plants
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Catalytically Active Proteasomes Function Predominantly in the Cytosol.

Francis Wang Dang1, Li Chen1, Kiran Madura2

  • 1From the Department of Pharmacology, Robert Wood Johnson Medical School-Rutgers University, Piscataway, New Jersey 08854.

The Journal of Biological Chemistry
|July 16, 2016
PubMed
Summary
This summary is machine-generated.

Catalytically active proteasomes, the cell

Keywords:
E3 ubiquitin ligasenuclear envelopenuclear poreproteasomeprotein degradationprotein exportproteolysis

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Area of Science:

  • Cell Biology
  • Molecular Biology

Background:

  • The ubiquitin/proteasome pathway is crucial for intracellular protein degradation.
  • The precise sites of nuclear protein degradation remain poorly understood.
  • Subcellular distribution of peptidase activity has not been systematically investigated.

Purpose of the Study:

  • To investigate the subcellular localization of proteasomes.
  • To provide conclusive evidence on the sites of intracellular protein degradation.

Main Methods:

  • Systematic investigation of peptidase activity distribution.
  • Subcellular localization studies of proteasomes.

Main Results:

  • Catalytically active proteasomes are found almost exclusively in the cytosol.
  • Little to no peptidase activity was detected in the nucleus.
  • Nuclear proteins are likely degraded by cytosolic proteasomes after export.

Conclusions:

  • Nuclear protein degradation primarily occurs in the cytosol.
  • Export of substrates from the nucleus is a key regulatory step.
  • Cytosolic proteasomes play a dominant role in degrading nuclear proteins.