The expanding family of MyD88-like adaptors in Toll-like receptor signal transduction

Toll-like receptors (TLRs) play an essential role in the detection and elimination of invading microbes. They are type-1 transmembrane receptors, containing extracellular leucine rich repeats and an intracellular Toll/interleukin-1 receptor (TIR) domain. Upon stimulation, these receptors interact with specific TIR domain-containing adaptor proteins. Five such adaptors have been discovered to date, MyD88, Mal (MyD88 adaptor-like)/TIRAP (TIR domain-containing adaptor protein), Trif (TIR-domain-containing adaptor inducing interferon-beta), TRAM (Trif-related adaptor molecule) and SARM (SAM and ARM-containing protein). Different TLRs use different combinations of these adaptors, leading to the activation of common and unique pathways involved in the elimination of the invading microbe. (C) 2004 Elsevier Ltd. All rights reserved.