The TLR family plays a fundamental role in pathogen recognition and activation of innate immunity. TLRs are highly conserved from Drosophila to humans and share structural and functional similarities. They recognize pathogen-associated molecular patterns (PAMPs) that are expressed on infectious agents, and mediate the production of cytokines necessary for the development of effective immunity. The various TLRs exhibit different patterns of expression. This gene product is expressed in myelomonocytic cells, and recognizes bacterial flagellin, a principle component of bacterial flagella and a virulence factor. The activation of this receptor mobilizes the nuclear factor NF-κB and stimulates tumor necrosis factor-alpha production.
TLR5 recognizes flagellin.Flagellin is the protein monomer that makes up the filament of bacterial flagella, found on nearly all motile bacteria. There are highly conserved regions in the flagellin protein among all bacteria, facilitating the recognition of flagellin by a germ-line encoded receptor such as TLR5.
^Hayashi F, Smith KD, Ozinsky A, Hawn TR, Yi EC, Goodlett DR, Eng JK, Akira S, Underhill DM, Aderem A (April 2001). "The innate immune response to bacterial flagellin is mediated by Toll-like receptor 5". Nature410 (6832): 1099–103. doi:10.1038/35074106. PMID11323673.
^Smith KD, Andersen-Nissen E, Hayashi F, Strobe K, Bergman MA, Barrett SL, Cookson BT, Aderem A (December 2003). "Toll-like receptor 5 recognizes a conserved site on flagellin required for protofilament formation and bacterial motility". Nature Immunology4 (12): 1247–53. doi:10.1038/ni1011. PMID14625549.