dsRNA-binding proteins in innate immunity. (a) Network of dsRNA sensors and modulators in innate immunity. The diagram below shows their interdependence. Blue arrows and red inhibition lines indicate reported stimulatory and inhibitory relationships, respectively. (b) Structures of dsRNA and dsDNA, which display A-form and B-form double helixes, respectively. (c) Watson-Crick base pair interactions, with edges facing major versus minor grooves indicated. Note that relative locations of hydrogen bond donors and acceptors differ for all four nucleotides in the major groove but are degenerate in the minor groove. Abbreviations: ADAR, adenosine deaminase acting on RNA; PKR, protein kinase R; RLR, RIG-I-like receptor.