Tumor Necrosis Factor Receptor (TNFR)-Associated Factor (TRAF) family, TRAF3 subfamily, TRAF domain; TRAF molecules serve as adapter proteins that link TNFRs and downstream kinase cascades resulting in the activation of transcription factors and the regulation of cell survival, proliferation and stress responses. TRAF3 was first described as a molecule that binds the cytoplasmic tail of CD40. However, it is not required for CD40 signaling. More recently, TRAF3 has been identified as a key regulator of type I interferon (IFN) production and the mammalian innate antiviral immunity. It mediates IFN responses in Toll-like receptor (TLR)-dependent as well as TLR-independent viral recognition pathways. It is also a key element in immunological homeostasis through its regulation of the anti-inflammatory cytokine interleukin-10. TRAF3 contains a RING finger domain, five zinc finger domains, and a TRAF domain. The TRAF domain can be divided into a more divergent N-terminal alpha helical region (TRAF-N), and a highly conserved C-terminal MATH subdomain (TRAF-C) with an eight-stranded beta-sandwich structure. TRAF-N mediates trimerization while TRAF-C interacts with receptors.