- Proteasomes are multi-protein complexes located in the cytosol and nucleus.
- The proteasomes consist of two major sub-complexes:
- the catalytic particle (20 S particle) and
- the regulatory particle (19 S particle)
- The proteasomes recognize polyubiquitinated proteins with ubiquitin chains of at least 4 ubiquitin molecules and degrades them into small peptides, 3-22 residues long.
- The ubiquitin molecules are recycled.