Melatonin receptor

A melatonin receptor is a G protein-coupled receptor (GPCR) which binds melatonin.

Three types of melatonin receptor have been cloned. The MT1 (or Mel1a or MTNR1A) and MT2 (or Mel1b or MTNR1B) receptor subtypes are present in humans and other mammals, while an additional melatonin receptor subtype Mel1c has been identified in amphibia and birds.

Expression patterns
In mammals, melatonin receptors are found in the brain and some peripheral organs. However, there is considerable variation in the density and location of the expression of melatonin receptors between species. The MT1 subtype is present in the pars tuberalis of the pituitary gland and the suprachiasmatic nuclei of the hypothalamus. The MT2 subtype is mainly present in the retina. The Mel1c type receptor of many lower vertebrates is expressed in many brain areas.