20S Proteasome (human) (untagged)

The ubiquitin-proteasome pathway is the major proteolytic system in eukaryotic cells, where it catalyzes the selective degradation of short-lived regulatory proteins or the rapid turnover of misfolded proteins. One of the most important proteases in this pathway is the 26S proteasome, an ATP-dependent proteolytic complex, which is formed by the association of the barrel-shaped 20S proteasome (700kDa) and two 19S (700kDa) regulatory complexes. The 20S catalytic core is composed of 4 rings of 28 non-identical subunits; 2 rings are composed of 7 alpha-subunits and 2 rings are composed of 7 beta-subunits. The 20S catalytic core is able to degrade a variety of peptide substrates and poly-ubiquitinated proteins involved with apoptosis, DNA repair, endocytosis and cell cycle control.