Over forty homologous proteins belong to the superfamily of ligand-gated ion channels. These members are broken down into different subfamilies, for example: acetylcholine, serotonin and glycine receptors. A new member has been added to this superfamily – ZAC (zinc-activated channel) which is expressed in human and dog but not in rodents. Like all other ligand-gated ion channels, ZAC has four transmembrane domains and extracellular N- and C-termini. As its name states, the channel is activated by high concentrations of zinc. ZAC mRNA was found to be expressed in placenta, spinal cord, stomach, and fetal brain. In another study, ZAC was identified using a computer-assisted program and was detected in similar areas (including pancreas and kidney), but also displayed minor discrepancies. Being that the channel is expressed in human and dog, deciphering its cellular/physiological functions will be challenging.