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Tumor Necrosis Factor Receptor (TNFR) Associated Factor (TRAF) family, TRAF1 subfamily, TRAF domain, C-terminal MATH subdomain; 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. TRAF1 expression is the most restricted among the TRAFs. It is found exclusively in activated lymphocytes, dendritic cells and certain epithelia. TRAF1 associates, directly or indirectly through heterodimerization with TRAF2, with the TNFR family receptors TNFR-2, CD30, RANK, CD40 and LMP1, among others. It also binds the intracellular proteins TRADD, TANK, TRIP, RIP1, RIP2 and FLIP. TRAF1 is unique among the TRAFs in that it lacks a RING domain, which is critical for the activation of nuclear factor-kappaB and Jun NH2-terminal kinase. Studies on TRAF1-deficient mice suggest that TRAF1 has a negative regulatory role in TNFR-mediated signaling events. TRAF1 contains one zinc finger and one 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.