SCNN1B is a subunit of the epithelial sodium channel, ENaC. ENac has high sodium selectivity, low conductance, and amiloride sensitivity. The functional channel of ENaC is composed of at least 3 subunits, alpha (SCNN1A), beta (SCNN1B), and gamma (SCNN1G). The 3 subunits show sequence similarities to one another, indicating descent from a common ancestral gene. Each encodes a protein containing 2 transmembrane domains, with intracellular amino and carboxyl termini. ENaC in the kidney, lung and colon plays an essential role in trans- epithelial sodium and fluid balance. ENaC also mediates aldosterone-dependent sodium re-uptake in the distal nephron of the kidney, thus regulating blood pressure. Mutations in beta or gamma subunit of the epithelial sodium channel (ENaC) have been found to cause a hereditary form of human hypertension, Liddle syndrome.