Receptor for MSH (alpha, beta and gamma) and ACTH (By similarity). The activity of this receptor is mediated by G proteins which activate adenylate cyclase (By similarity). Mediates melanogenesis, the production of eumelanin (black/brown) and phaeomelanin (red/yellow), via regulation of cAMP signaling in melanocytes (By similarity). Interacts with MGRN1, but does not undergo MGRN1-mediated ubiquitination; this interaction competes with GNAS-binding and thus inhibits agonist-induced cAMP production. Interacts with OPN3; the interaction results in a decrease in MC1R-mediated cAMP signaling and ultimately a decrease in melanin production in melanocytes. The allele MC1R-delta-15 is associated with melanistic coat coloration. Belongs to the G-protein coupled receptor 1 family.