Department of Molecular Science and Technology, Ajou University Suwon, South Korea.
Front Physiol. 2011 Jul 27;2:41. doi: 10.3389/fphys.2011.00041. eCollection 2011.
Toll-like receptors (TLRs) are pattern recognition receptors that recognize conserved structures in pathogens, trigger innate immune responses, and prime antigen-specific adaptive immunity. Elucidation of crystal structures of TLRs interacting with their ligands such as TLR1-2 with triacylated lipopeptide, TLR2-6 with diacylated lipopeptide, TLR4-MD-2 with LPS, and TLR3 with double-stranded RNA (dsRNA) have enabled an understanding of the initiation of TLR signaling. Agonistic ligands such as LPS, dsRNA, and lipopeptides induce "m" shaped TLR dimers in which C-termini converge at the center. Such central convergence is necessary to bring the two intracellular receptor TIR domains closer together and promote their dimerization, which serves as an essential step in downstream signaling. In this review, we summarize TLR ECD structures that have been reported to date with special emphasis on ligand recognition and activation mechanism.
Toll 样受体（TLRs）是一种模式识别受体，能够识别病原体中的保守结构，触发先天免疫反应，并启动抗原特异性适应性免疫。阐明 TLR 与其配体相互作用的晶体结构，如 TLR1-2 与三酰化脂肽、TLR2-6 与二酰化脂肽、TLR4-MD-2 与 LPS、TLR3 与双链 RNA（dsRNA），使我们能够了解 TLR 信号的起始。激动剂配体，如 LPS、dsRNA 和脂肽，诱导“m”形 TLR 二聚体，其中 C 末端在中心会聚。这种中央会聚对于使两个细胞内受体 TIR 结构域更接近并促进它们的二聚化是必要的，这是下游信号转导的一个重要步骤。在这篇综述中，我们总结了迄今为止报道的 TLR ECD 结构，特别强调了配体识别和激活机制。
