Proteasome subunit beta type (PSMB)

Proteasome subunit beta type is a class of proteins that constitute the beta subunits of the 20S core proteasome complex, a large, multisubunit protease responsible for the ATP/ubiquitin-dependent degradation of intracellular proteins. The 20S core is a barrel-shaped assembly composed of four rings: two outer alpha rings and two inner beta rings, each containing seven subunits. Of the beta subunits, types 1, 2, and 5 (e.g., PSMB1, PSMB2, PSMB5) contain proteolytically active sites that confer different cleavage specificities (caspase-like, trypsin-like, chymotrypsin-like activities). These subunits are essential for regulated protein degradation, controlling cell cycle, apoptosis, and immune responses. Dysfunction or altered expression of these subunits is implicated in various disease processes, and selective inhibition of proteasome beta subunits (particularly beta type-5) has led to the development of clinically approved anti-cancer drugs.

Other names

Proteasome beta subunit20S proteasome beta subunitPSMB family20S proteasome subunit beta-6

Inhibition of proteasome activity (typically targeting the chymotrypsin-like activity of the beta type-5 subunit), leading to accumulation of ubiquitinated proteins, cell cycle arrest, and apoptosis