26S proteasome non-ATPase regulatory subunit 4 (PSMD4)

Part of the 26S proteasome, a multiprotein complex involved in the ATP-dependent degradation of ubiquitinated proteins. This complex plays an integral role in the maintenance of protein homeostasis by eliminating misfolded or damaged proteins, which could impair cellular functions, and by eliminating proteins whose functions are no longer required.

Therefore, the proteasome participates in numerous cellular processes, including cell cycle progression, apoptosis, or DNA damage repair. PSMD4 acts as an ubiquitin receptor subunit via ubiquitin-interacting motifs and selects ubiquitin-conjugates for destruction.