Melanocortin Receptor Type 1 (MC1R)

The melanocortin 1 receptor (MC1R) is a G protein–coupled receptor primarily involved in regulating skin and hair pigmentation. It controls the type of melanin (eumelanin or pheomelanin) produced by melanocytes. Activation favors eumelanin synthesis, providing UV protection, while lack of activation leads to pheomelanin production, offering less UV protection. MC1R also plays a role in immune modulation and, recently discovered, in cholesterol and bile acid metabolism in hepatocytes. Genetic variations are associated with red hair, fair skin, freckles, and increased melanoma risk due to impaired DNA repair after UV exposure.

Other names

Melanocyte-stimulating hormone receptor (MSHR)Melanotropin receptorMelanin activating peptide receptor

Activation increases cAMP signaling, leading to upregulation of melanin production and enhanced nucleotide excision repair.