The Toll–IL-1 receptor adaptor family grows to five members

Toll-like receptor (TLR) signal transduction is mediated by an adaptor protein termed MyD88. In the case of TLR2 and TLR4, another adaptor related to MyD88 called Mal also participates in signalling. Two recent papers have added a third adaptor to the family, called Toll–interleukin-1 receptor (TIR) domain-containing adaptor inducing interferon-β (IFN-β) (TRIF) or TIR-containing adaptor molecule-1 (TICAM-1), which is particularly important for IFN regulatory factor-3 (IRF-3) activation by antiviral TLR3. Two additional adaptors are present in humans, termed Trif-related adaptor molecule (TRAM) and sterile α and HEAT–Armadillo motifs (SARM). It is probable that differential use of adaptors will help explain the distinct pathways activated by TLRs during host defence.