Toll and Toll-like receptors in Drosophila.

The Drosophila Toll receptor controls the immune response to Gram-positive bacteria and fungi by activating a signalling pathway partially conserved throughout evolution. The Drosophila genome encodes eight additional Toll-related receptors, most of which appear to carry out developmental rather than immune functions. One exception may be Toll-9, which shares structural and functional similarities with mammalian TLRs.