Melatonin Receptor

Melatonin receptors belong to the G protein-coupled receptor superfamily, which preferentially couple to Gα_i/o proteins. The melatonin receptor subfamily is composed of three members in mammals: MT₁ and MT₂, which are both binding to the neurohormone melatonin with high affinity, and GPR50, which shows high sequence homology to MT₁ and MT₂ but does not bind to melatonin or any other known ligand.

MT₁ and MT₂ are involved in various biological functions including the regulation of biological rhythms, sleep, pain, retinal, neuronal and immune functions. Alteration of melatonin receptor function or expression in humans is associated with depression, Alzheimer’s disease and type 2 diabetes.