The epithelial sodium channel (ENaC) is a member of the ENaC/DEG superfamily that is located on the apical surface of cells. ENaC mediates sodium reabsorption in kidney, distal colon, lung, ducts of exocrine glands and other organs. ENaC is formed by heteromultimerization of four homologous subunits, alpha, beta, gamma and delta. The most frequently formed heterotetramer consists of 2alpha, 1beta, and 1gamma subunit, but the alpha subunit can be replaced by a delta subunit. The alphaENaC gene maps to human chromosome 12p13, and expresses a glycosylated protein. Both the beta and gamma ENaC genes map to human chromosome 16p12, and the gamma ENaC transcript is detected as a glycosylated protein. The carboxy-terminus of all ENaC subunits contains PY motifs, which interact with the ubiquitin protein ligase, Nedd4, to regulate intracellular sodium concentrations. Gain-of-function mutations involving the PY motif cause Liddle