The function of ENSG00000258839 (MC1R, melanocortin 1 receptor) is as follows. G protein-coupled receptor that binds melanocyte-stimulating hormones (alpha, beta, and gamma-MSH) and adrenocorticotropic hormone/ACTH, which are peptide products of the POMC precursor protein (PubMed:11442765, PubMed:11707265, PubMed:1325670, PubMed:1516719, PubMed:8463333). Upon activation, MC1R couples with the G(s) protein, stimulating adenylate cyclase and activating the cAMP-dependent signaling pathway. This activation promotes melanogenesis, resulting in the production of eumelanin (black/brown) and pheomelanin (red/yellow) in melanocytes (PubMed:11707265, PubMed:1325670, PubMed:16463023, PubMed:19737927, PubMed:31097585, PubMed:34453129). MC1R interacts with G protein-coupled receptor opsin 3/OPN3, which couples to G(i) proteins and inhibits the alpha-MSH-induced cAMP response, thereby reducing melanin synthesis (PubMed:31097585). Binding to Agouti/ASP precludes alpha-MSH-induced signaling, thereby downregulating melanogenesis (By similarity). Additionally, interaction with MGRN1 displaces the G(s) protein, further suppressing MC1R signaling (PubMed:19737927). {ECO:0000250|UniProtKB:Q01727, ECO:0000269|PubMed:11442765, ECO:0000269|PubMed:11707265, ECO:0000269|PubMed:1325670, ECO:0000269|PubMed:1516719, ECO:0000269|PubMed:16463023, ECO:0000269|PubMed:19737927, ECO:0000269|PubMed:31097585, ECO:0000269|PubMed:34453129, ECO:0000269|PubMed:8463333}.