Accepts ubiquitin from the E1 complex and catalyzes its covalent attachment to other proteins. In vitro 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 auto-ubiquitination of CHIP, TRAF6 and TRIM63/MURF1. Ubiquitinates CHIP-associated HSP90AB1 in vitro. Lacks inherent specificity for any particular lysine residue of ubiqui