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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 ?
(2003) Inhibition of proteasome activity induces concerted expression of proteasome genes and de novo formation of mammalian proteasomes.
To further investigate the relationship between the inactivity of proteasome and the expression of IL-6 in RPE, we evaluated the effect of inhibition of proteasome activity on the production of IL-6 as well as other relevant inflammatory cytokines and its mechanism.
showed that the elevated activity of circulating 20S proteasomes reflects cellular tissue damage and might be a useful biomarker of disease severity and progression [19, 20].
Ubiquitination and subsequent degradation by the proteasome have been regarded as the main mechanism responsible for Nrf2's negative regulation.
Similar to LXR agonists, T0901317 and GW3965, that inhibit OPN expression and the severity of DN in STZ diabetic mice [42], the delivery of peptides that inhibit PA28 binding to 20S proteasomes, the XAPC7, HBX, and TAT-conjugated peptides inhibited OPN release from mesangial cells under high glucose conditions.
Mean centroid of the 31 and 55 upregulated genes in the core enrichment of proteasome and spliceosome pathways showed no correlation with insulin secretion but positively correlated with HbA1c level (Figures 2(e)-2(f)).
The central role of the 26S proteasome in the selective degradation of intracellular proteins involved in the cell cycle has made it a target of considerable interest in the development of novel anticancer therapeutics.
In the following sections we will discuss these and additional data suggesting an involvement of proteasomes in specific pathways underlying MS.
Ever since the ubiquitin proteasome system (UPS) was first characterized in the mid-20th century as the primary mediator of regulated protein degradation, its role in neurons has come under ever increasing scrutiny.
Changes in proteasome activity in the ischemic kidney of rat with experimental renovascular hypertension.
Bortezomib is a widely used proteasome inhibitor that has proven to be very effective in treating multiple myeloma.
Malin Hernebring found damaged proteins in the cells are probably broken down by molecular machines called proteasomes.

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