 It is thought that the well-conserved extracellular domains serve as receptors to control the activities of the channels.The vertebrate ENaC proteins from epithelial cells cluster tightly together on the phylogenetic tree; voltage-insensitive ENaC homologues are also found in the brain.The many sequenced C. elegans proteins, including the worm degenerins, are distantly related to the vertebrate proteins as well as to each other.