Degradation by proteasomes is part of the mechanism by which cells regulate the concentration of proteins and degrade misfolded proteins. Proteasomes are protein complexes which degrade unneeded or damaged proteins by proteolysis, a chemical reaction that breaks peptide bonds. Proteins are tagged for degradation by proteasomes by the addition of ubiquitin, by ubiquitin ligases.
Description adapted from [Wikipedia](https://en.wikipedia.org/wiki/Proteasome).
Proteins on this pathway have targeted assays available via the [CPTAC Assay Portal](https://assays.cancer.gov/available_assays?wp_id=WP183)