MC1Rs

MC1R refers to the melanocortin 1 receptor. It is a cell surface G protein-coupled receptor that is primarily found in melanocytes, the cells responsible for producing melanin, the pigment that gives color to skin, hair, and eyes. The MC1R gene provides instructions for making this receptor protein.

When MC1R is activated by its ligands, such as alpha-melanocyte-stimulating hormone (α-MSH), it triggers a signaling cascade that influences the type of melanin produced. Specifically, activation of MC1R promotes the production of eumelanin, a dark brown or black pigment. Conversely, when MC1R signaling is less active or absent, pheomelanin, a red or yellow pigment, is favored.

Variations in the MC1R gene can lead to differences in the amount and type of melanin produced, which in turn affects hair and skin color. Individuals with certain MC1R gene variants are more likely to have lighter skin, red hair, and freckles. These variants are also associated with an increased susceptibility to sunburn and a higher risk of developing melanoma, the deadliest form of skin cancer, due to less efficient production of protective eumelanin. Research continues to explore the full range of MC1R's roles in pigmentation and its implications for health.