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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 ?
We introduced the first proteasome inhibitor for multiple myeloma, VELCADE, into clinical research approximately 20 years ago.
As you age, the function of the proteasome declines, and the removal of damaged proteins slows.
MLN9708 is an investigational oral proteasome inhibitor that is being studied in multiple myeloma, various other hematologic malignancies and solid tumors.
The researchers then tested their findings by blocking Nrf2 with various chemical and genetic inhibitors, which in turn decreased the cell's ability to make more proteasome and cope with the hydrogen peroxide.
Immune defects in 28-kDa proteasome activator gamma-deficient mice.
For example, researchers need to examine the combinatorial effects of PIs and alcohol on the proteasome and its functionality, as well as the effects of NRTIs and alcohol on the respiratory chain, the various electron transport complexes, and the integrity of mtDNA in hepatocytes.
These results indicate that proteasome activity is stimulated by mild denaturing treatments.
Nereus Pharmaceuticals' second candidate, NPI-0052, functions as a highly potent proteasome inhibitor that is in development for the treatment of multiple myeloma, solid tumours, lymphomas and leukaemias.
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.
The resulting "ubiquitin-conjugated proteins" latch onto the proteasome enzyme, which degrades the proteins.
Last year, the Food and Drug Administration approved the proteasome inhibitor bortezomib (Velcade) for the treatment of multiple myeloma, a cancer of the blood.
Velcade is the first of a new class of medicines called proteasome inhibitors.

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