Could be involved in the transport of tyrosine, the precursor to melanin synthesis, within the melanocyte. Regulates the pH of melanosome and the melanosome maturation. One of the components of the mammalian pigmentary system. Seems to regulate the postranslational processing of tyrosinase, which catalyzes the limiting reaction in melanin synthesis. It can modulate intracellular glutathione metabolism. Most abundant in melanocytes. Also present in neonatal and adult eye tissue presumably as a result of expression in the retinal pigmented epithelium and choroid body, known sites of melanogenesis in the eye. Small but detectable amounts also observed in fetal, neonatal and adult brain. Moderate amounts detected in adult testis and ovary. Not detected in heart, kidney, spleen, liver or thymus. Defects in Oca2 are a cause of hypopigmentation of the eyes, skin, and fur. The protein is missing or altered in six independent mutant alleles of the OCA2 locus, suggesting that disruption of this gene results in hypopigmentation phenotype that defines mutant OCA2 alleles. Belongs to the CitM (TC 2.A.11) transporter family. Questioning colour - Issue 54 of January 2005