Proteasome 20S subunit alpha 4 (PSMA4)

Proteasome 20S subunit alpha 4 (PSMA4) is a core component of the 20S proteasome, an ATP- and ubiquitin-dependent multicatalytic proteinase complex responsible for the regulated degradation of most intracellular proteins in eukaryotic cells. The 20S proteasome is composed of four stacked rings of 28 subunits (two rings of seven alpha subunits, two of seven beta subunits); PSMA4 is one of the alpha subunits forming the gates that regulate substrate entry to the proteolytic chamber. As part of the larger 26S proteasome complex, PSMA4 contributes to protein homeostasis by removing misfolded, damaged, or unneeded proteins. It plays key roles in cell cycle control, antigen processing for MHC class I presentation, and embryonic development, among others. PSMA4 and the proteasome are implicated in various diseases, most notably cancer and neurodegenerative diseases, and are important therapeutic targets for clinically approved proteasome inhibitors such as bortezomib and carfilzomib.

Other names

Proteasome subunit alpha type-4PSMA4PSC9alpha-3HC9HsT17706Macropain subunit C9Multicatalytic endopeptidase complex subunit C9Proteasome component C9Proteasome subunit LProteasome subunit alpha-3Proteasome subunit α320S proteasome alpha 4 subunitC9

Inhibition of proteasomal proteolytic activity leading to accumulation of ubiquitinated proteins, induction of apoptosis, and impaired protein homeostasis