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Cytoplasmic organelle, composed of a cylindric core particle bound by two regulatory particles at each end, responsible for degrading endogenous proteins. Proteins to be destroyed are recognized by proteasomes because of the presence of ubiquitin conjugated to the targeted protein's lysine residue.
See also: ubiquitin-protease pathway.
[protease + -some ]


A cellular protein complex consisting of proteolytic enzymes that degrade endogenous proteins, especially those that are damaged, pathogenic, or no longer of use.


, proteosome (prō′tē-ă-sōm″)
An enzymatic (protease) cell organelle that degrades misfolded or damaged proteins and modulates the quantity of regulatory proteins in the cell. The breakdown of proteins by proteasomes (proteolysis) is triggered when damaged proteins are tagged by ubiquitin.


A large, cylindrical protein complex of several sub-units, present in the cytoplasm and nucleus of all cells and an essential component in cell metabolism. The function of the proteasome is to act as a kind of shredder, degrading unwanted proteins that have been tagged for destruction with UBIQUITIN chains. It strips proteins of their ubiquitin, unfolds them and catalyzed them to peptides. Proteasomes have aroused much interest as therapeutic trargets in cancer. The proteasome 26S is involved both in the induction and repression of APOPTOSIS. See also POLYUBIQUITINATION.
References in periodicals archive ?
The accumulation of p-tau at the synapse mirrors the accumulation of ubiquitinylated proteins in the same fraction, as well as the accumulation of proteasomes and related chaperones, consistent with the notion that tau aggregates are associated with impaired proteolysis mediated by the UPS [82].
Changes in proteasome activity in the ischemic kidney of rat with experimental renovascular hypertension.
Immune defects in 28-kDa proteasome activator gamma-deficient mice.
Inhibition of proteasome function leads to NF-kappaB-independent IL-8 expression in human hepatocytes.
Crude proteasomes were extracted from pressurized (0.
2) used ELISA to measured the concentrations of circulating proteasomes in sera from patients with hematologic malignancies and with various liver diseases and found that they were substantially higher than circulating proteasome in plasma of healthy patients.
Inhibition of proteasome activity induces concerted expression of proteasome genes and de novo formation of mammalian proteasomes.
A cell marks proteins with this "kiss of death" molecule--itself a small protein--and then shuttles the doomed proteins to its waste-disposal units, called proteasomes.
Selective inhibition of cancer cell proteasomes blocks the cancer cell's metabolic regulators and induces cancer cell apoptosis.
Los resultados indican que: a) espermatozoides intactos fueron capaces de hidrolizar los substratos de proteasomes SLLVY-AMC y azocaseina.
This volume of Progress in Molecular Biology and Translational Science discusses cutting-edge research of proteasomes and proteasome-associated proteins and cellular systems.
These results suggest that the increased proteasome activity may be due to posttranslational modifications or changes in the levels of associating partners on the proteasomes rather than its expression.

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