Toll-like receptors: structural pieces of a curve-shaped puzzle.

The toll-like receptors are responsible for recognizing invading pathogens and triggering a primary innate immune response by initiating a signalling pathway that ultimately leads to the activation of nuclear factor-kappaB (NF-kappaB). NF-kappaB induces the transcription of many genes that regulate both the inflammatory response and interferons that help control the development of adaptive immunity. In this review, we concentrate on the structure and function of toll-like receptors and our current understanding of the complexities of ligand binding, receptor dimerization and signal transduction.