The Toll family of receptors includes several related proteins involved in plant and animal development and defense. Mammalian TLRs are a large family with at least 11 members, of which humans encode the first ten. Individual TLRs are critical in recognizing pathogen-derived microbial components such as bacteria, fungi, protozoa, and viruses. The toll was discovered at the end of the twentieth century in Drosophila melanogaster as a gene controlling the developing embryo’s dorsal-ventral axis. One year later, it was discovered that a mammalian homolog of the Toll receptor (now known as TLR4) could induce the expression of genes involved in inflammatory responses. Foll...
