Accepts ubiquitin from the E1 complex and catalyzes its covalent attachment to other proteins (   ). Catalyzes 'Lys-48'-linked polyubiquitination (   , ). Mediates the selective degradation of short-lived and abnormal proteins (   , ). Functions in the E6/E6-AP-induced ubiquitination of p53/TP53 . Mediates ubiquitination of PEX5 and autoubiquitination of STUB1 and TRAF6 . Involved in the signal-induced conjugation and subsequent degradation of NFKBIA, FBXW2-mediated GCM1 ubiquitination and degradation, MDM2-dependent degradation of p53/TP53 and the activation of MAVS in the mitochondria by RIGI in response to viral infection (, ). Essential for viral activation of IRF3 .