Proteasome (None)

The proteasome is a large, multi-subunit protease complex found in all eukaryotes and archaea, and in some bacteria. It is essential for the regulated degradation of intracellular proteins by proteolysis. The primary function of the proteasome is to maintain protein homeostasis by degrading misfolded, damaged, or regulatory proteins that have been tagged with ubiquitin. In eukaryotes, the 20S core associates with one or two 19S regulatory particles to form the 26S proteasome holoenzyme. The 19S cap recognizes polyubiquitinated substrates, unfolds them using ATP hydrolysis, removes ubiquitin chains, and translocates unfolded polypeptides into the catalytic chamber for degradation. Proteins destined for degradation are tagged with polyubiquitin chains via an enzymatic cascade. Ubiquitinated substrates are recognized by receptors on the 19S regulatory particle. After deubiquitination and unfolding driven by ATP hydrolysis, substrates are threaded into the central chamber where they are cleaved into small peptides. These peptides can be further processed or presented on MHC class I molecules for immune surveillance. Its activity ensures removal of abnormal or excess proteins to prevent cellular dysfunctions such as those seen in cancer or neurodegenerative diseases.

Other names

26S Proteasome20S ProteasomeUbiquitin-Proteasome System (UPS)

Proteasome inhibition