Accepts ubiquitin from the E1 complex and catalyzes its covalent attachment to other proteins (PubMed:10329681, PubMed:18042044, PubMed:18703417, PubMed:20061386, PubMed:20403326, PubMed:20525694, PubMed:26475854, PubMed:28322253). Catalyzes 'Lys-48'- linked polyubiquitination (PubMed:10329681, PubMed:18042044, PubMed:18359941, PubMed:18703417, PubMed:20061386, PubMed:20403326, PubMed:20525694, PubMed:26475854). Mediates the selective degradation of short-lived and abnormal proteins (PubMed:10329681, PubMed:18042044, PubMed:18359941, PubMed:18703417, PubMed:20061386, PubMed:20403326, PubMed:20525694, PubMed:26475854). Functions in the E6/E6-AP-induced ubiquitination of p53/TP53 (PubMed:15280377). Mediates ubiquitination of PEX5 and SQSTM1 and autoubiquitination of STUB1 and TRAF6 (PubMed:18359941, PubMed:28322253). 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 (PubMed:18703417, PubMed:20403326). Essential for viral activation of IRF3 (PubMed:19854139). {ECO:0000269|PubMed:10329681, ECO:0000269|PubMed:15280377, ECO:0000269|PubMed:18042044, ECO:0000269|PubMed:18359941, ECO:0000269|PubMed:18703417, ECO:0000269|PubMed:19854139, ECO:0000269|PubMed:20061386, ECO:0000269|PubMed:20403326, ECO:0000269|PubMed:20525694, ECO:0000269|PubMed:26475854, ECO:0000269|PubMed:28322253}. This is the function of Ensembl gene identifier ENSG00000131508 (UBE2D2, ubiquitin conjugating enzyme E2 D2).