SKN-1 is the C. elegans ortholog of mammalian Nrf/CNC proteins. (A) Similarities between SKN-1 and Nrf/CNC proteins. SKN-1 and Nrf/CNC proteins are most closely related within the DIDLID and DNA-binding regions [6,17]. SKN-1 interacts directly with specific DNA sequences through its BR, which is highly similar to that of Nrf/CNC proteins, and a short element that binds in the minor groove (light blue) [11]. The CNC domain stabilizes these interactions. (B) Comparison of SKN-1 binding site with the ARE. SKN-1 and Nrf-Maf dimers each bind to sequences that include a consensus bZIP protein half-site (underlined), but diverge within the reminder of the binding site, where SKN-1 binds the consensus WWT in the minor groove [11]. (C) Simple diagram of SKN-1 isoforms. Expression of SKN-1d is predicted but has not been confirmed in vivo. skn-1 exons are drawn approximately to scale (WormBase Web site, skn-1, available at http://www.wormbase.org/db/get?name=skn-1:class=Gene).