Catalyzes the covalent attachment of ubiquitin to other proteins. Functions in the selective degradation of misfolded membrane proteins from the endoplasmic reticulum (ERAD) and is essential for cells to recover from ER stress (PubMed:28321712). Plays a role in MAPKAPK2-dependent translational control of TNF synthesis (PubMed:24020373). Also acts as a platform for perinuclear positioning of the endosomal system by mediating ubiquitination of SQSTM1 through interaction with the E3 ubiquitin-protein ligase RNF26 (PubMed:33472082). Plays a role in male fecundity through the interaction with the E3 ubiquitin-protein ligase RNF133 (PubMed:35831855). {ECO:0000255|PROSITE-ProRule:PRU00388, ECO:0000269|PubMed:12082160, ECO:0000269|PubMed:22607976, ECO:0000269|PubMed:24020373, ECO:0000269|PubMed:28321712, ECO:0000269|PubMed:33472082, ECO:0000269|PubMed:35831855}. (Microbial infection) Promotes Dengue virus RNA replication by negatively regulating IFN-beta signaling and mediating 'Lys-48'- linked ubiquitination on IRF3 (PubMed:30157886). . This is the function of Ensembl gene identifier ENSG00000198833 (UBE2J1, ubiquitin conjugating enzyme E2 J1).