Caenorhabditis elegans degenerins and vertebrate ENaC ion channels containan extracellular domain related to venom neurotoxins

The DEG/ENaC (DEGenerin/Epithelial Na+ Channel) superfamily includes closel y related ion channel subunits from divergent species ranging from the simp le nematode Caenorhabditis elegans to humans. Members of this protein group play roles in several important processes including transduction of mechan ical stimuli, sodium re-absorption and blood pressure regulation. Structure /function relationships in members of this superfamily are just beginning t o be elaborated. Using a bioinformatics approach: we identified a novel str uctural element in the extracellular region of DEG/ENaC proteins that exhib its significant similarity to venom neurotoxins. Since venom neurotoxins bi nd to sodium channels at high affinity, we suggest that the related domain embedded in DEG/ENaC channels may interact with other regions of the channe l or channel complex to modulate channel function.