The proteasome is a major protein degradation system within cells, consisting of 20S core particles and 19S regulatory subunits, forming the 26S proteasome. It is primarily located in the cytoplasm and nucleus, responsible for degrading proteins tagged with ubiquitin, and participates in processes such as cell cycle control, signal transduction, and metabolic regulation. The proteasome family comprises diverse members, including various protease subunits and regulatory factors. Gene expression levels and activity are tightly regulated, and mutations or dysfunction are associated with various diseases such as cancer and neurodegenerative disorders. Proteasome inhibitors have been developed for the treatment of certain types of cancer.