Proteasome activator complex subunit gamma (PA28γ)

Proteasome activator complex subunit gamma (PA28γ, encoded by the PSME3 gene) is a regulatory component of the 11S proteasome activator complex. Unlike its α and β paralogs (which function predominantly in the immunoproteasome), PA28γ forms a nuclear-localized homoheptameric complex that binds to the 20S proteasome core, enhancing the degradation of several regulatory nuclear proteins in an ATP- and ubiquitin-independent manner. This activity is implicated in pivotal cellular processes including cell cycle progression, apoptosis, chromatin remodeling, and the DNA damage response. PA28γ also interacts with proteins such as p53 and Mdm2, contributing to the regulation of tumor suppression pathways. Dysregulation or overexpression of PA28γ has been associated with cancer and viral infections, but there are no approved drugs specifically targeting this subunit, and inhibiting it may have significant cellular consequences due to its fundamental role in proteostasis.

Other names

PA28 gammaREG gamma11S regulator gamma subunitProteasome activator subunit 3PSME3

Enhancement of 20S proteasome-mediated protein degradation (notably of regulatory proteins); Modulation of apoptosis and cell cycle through protein turnover; Regulation of immune function via non-classical pathways (distinct from PA28α/β, which are more involved in MHC class I antigen presentation)