Anatomy of TRAF2. Distinct domains for nuclear factor-kappaB activation and association with tumor necrosis factor signaling proteins.

The tumor necrosis factor (TNF) receptor-associated factor (TRAF) family of proteins interact with and transduce signals for members of the TNF receptor superfamily. TRAF1, TRAF2, and TRAF3 share a conserved C-terminal TRAF domain. TRAF2 plays a key role in transducing signals for activation of the transcription factor nuclear factor-kappaB (NF-kappaB). We have performed extensive mutational analysis on TRAF2, examining the requirements for NF-kappaB activation, self-association, and interaction with other molecules involved in TNF signaling. Examination of point mutants and TRAF2-TRAF3 chimeric proteins indicates that the N-terminal RING finger and two adjacent zinc fingers of TRAF2 are required for NF-kappaB activation. The two distinct TRAF-N and TRAF-C subdomains of the TRAF domain appear to independently mediate self-association and interaction with TRAF1. Interaction of TRAF2 with TNF-R2 and TRADD requires sequences at the C terminus of the TRAF-C domain, whereas interaction with the protein kinase receptor-interacting protein V(RIP) occurs via sequences at the N terminus of the TRAF-C domain. Thus, distinct domains of TRAF2 are involved in recruitment and signaling functions.