E3 ubiquitin ligase that catalyzes 'Lys-63'-linked polyubiquitination of target protein, enhancing protein-protein interaction and cell signaling (PubMed:19825828). Transfers ubiquitin from E2 ubiquitin-conjugating enzyme UBE2V1-UBE2N to substrate protein (PubMed:19825828). Essential adapter molecule in IL17A-mediated signaling (PubMed:19825828, PubMed:24120361). Upon IL17A stimulation, interacts with IL17RA and IL17RC receptor chains through SEFIR domains and catalyzes 'Lys-63'-linked polyubiquitination of TRAF6, leading to TRAF6-mediated activation of NF-kappa-B and MAPkinase pathways (PubMed:19825828). {ECO:0000269|PubMed:19825828, ECO:0000269|PubMed:24120361, ECO:0000269|PubMed:33723527}. This is the function of TRAF3IP2 (TRAF3 interacting protein 2, Ensembl gene identifier ENSG00000056972).