26S proteasome

The 26S proteasome is a large multi-protein complex that serves as the principal proteolytic machine responsible for regulated protein degradation in eukaryotic cells. It functions as the endpoint for the ubiquitin-proteasome system, playing a crucial role in protein homeostasis and numerous essential cellular processes. It consists of a 20S core particle containing proteolytic active sites (caspase-like, trypsin-like, chymotrypsin-like) and a 19S regulatory particle that recognizes ubiquitinated proteins, removes ubiquitin, unfolds substrates, and translocates them for degradation. An alternative regulatory particle, the 11S (PA28), can also associate with the 20S core. The 26S proteasome is essential for protein quality control, cell cycle regulation, signal transduction, stress responses, and immune system function.

Inhibition of regulated protein degradation mediated by the proteasome.