About TRAF / TNF receptor-Associated Factor:
TRAFs, or TNF receptor-associated factors, are a family of proteins that are mainly engaged in the regulation of inflammation, antiviral responses, and apoptosis. There have been seven of these found in mammals: TRAF1, TRAF2, TRAF3, TRAF4, TRAF5, TRAF6, and TRAF7. All of them, except for TRAF7, have a relatively conserved secondary structure.
TRAF Function
Each TRAF protein has its own function. The function of TRAF1 and TRAF2, for instance, is to form a heterodimeric complex, which is required for TNF-alpha-mediated activation of MAPK8/JNK and NF-kappaB. This complex also interacts with IAP and mediates the anti-apoptotic signals from TNF receptors. Meanwhile, TRAF3 participates in the signal transduction of CD40, a TNFR family member important for the activation of the immune response and is critical in the lymphotoxin-beta receptor signaling complex.
TNF receptor-Associated Factor Mechanism
The mechanisms for the TRAF proteins are still undergoing study and not all of them have been fully discovered.
TRAF Interactions
Each of the TRAF proteins has its own series of interactions. TRAF1 interacts with TRAF2, as well as CD40 (CD40 Molecule), BIRC3 (Baculoviral IAP Repeat Containing 3), CASP8 (Caspase 8), and SRC (SRC Proto-Oncogene, Non-Receptor Tyrosine Kinase). Meanwhile, TRAF3 interacts with CD40 (CD40 Molecule), TBK1 (TANK Binding Kinase 1), MAVS (Mitochondrial Antiviral Signaling Protein), IKBKE (Inhibitor of Nuclear Factor Kappa B Kinase Subunit Epsilon), and TICAM1 (Toll Like Receptor Adaptor Molecule 1).
TNF receptor-Associated Factor Structure
The TRAF domain is composed of 7–8 anti-parallel β-strand folds followed by a coiled-coil region that mediates protein interactions, usually forms mushroom-like trimeric structures in solution. This structure applies to all TRAF proteins.