Component of the 26S proteasome; a multiprotein complex involved in the ATP-dependent degradation of ubiquitinated proteins. This complex plays a key role in the maintenance of protein homeostasis by removing misfolded or damaged proteins; which could impair cellular functions; and by removing proteins whose functions are no longer required. Therefore; the proteasome participates in numerous cellular processes; including cell cycle progression; apoptosis; or DNA damage repair. PSMC3 belongs to the heterohexameric ring of AAA (ATPases associated with diverse cellular activities) proteins that unfolds ubiquitinated target proteins that are concurrently translocated into a proteolytic chamber and degraded into peptides.