TRAF3 A gene on chromosome 14q32.32 that encodes TNF receptor-associated factor 3, which regulates NF-kappaB kinase and MAP kinase activation, plays a central role in regulating B-cell survival, and is part of signalling pathways leading to cytokine and interferon production. TRAF3 is required for normal antibody isotype switching from IgM to IgG, and it plays a role in T-cell dependent immune responses as well as antiviral responses. It is an essential constituent of several E3 ubiquitin-protein ligase complexes and may promote Lys-63-linked ubiquitination of target proteins. It inhibits NF-kappaB activation in response to LTBR stimulation, as well as TRAF2-mediated NF-kappaB activation, and it downregulates proteolytic processing of NFKB2 and NF-kappaB activation. It promotes ubiquitination and proteasomal degradation of MAP3K14.