Molecular Components of the Toll and Imd Pathways Involved in Drosophila Immunity

<p>Toll is activated by the processed Spätzle (left). Toll activation leads to intracellular signaling via cytoplasmic proteins Tube and Pelle, leading to the degradation of Cactus and nuclear localization of NF-κB proteins Dorsal and Dif. These transcription factors bind to promoters of target genes, such as <i>drosomycin</i>, activating their transcription. The NF-κB protein for the Imd pathway, Relish, activates <i>diptericin</i> transcription. The signaling events resulting in Dorsal/Dif/Relish activation in the fly are “recycled” in mammals in the activation of mammalian NF-κB. See reviews and <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0020276#pbio-0020276-De1" target="_blank">De Gregorio et al. (2002)</a> for more details.