pattern recognition receptor signaling pathway toll-like receptor signaling pathway biological_process The series of molecular signals initiated by a ligand binding to a toll-like receptor of a target cell. Toll-like receptors directly bind pattern motifs from a variety of microbial sources to initiate an innate immune response. toll-like receptor signalling pathway TLR signaling pathway Note that the vertebrate toll-like receptors, unlike the Drosophila Toll molecule, directly bind their ligands. The Drosophila Toll molecule requires the Sptzle factor to bind microbial ligands and then the receptor in order to initiate innate immune responses. GO:0002224 Reactome:R-HSA-168898