Intracellular organelles mediate complex cell-based functions that often require ion-transport across their membranes. Melanosomes are organelles responsible for the synthesis of the major mammalian pigment melanin. Defects in melanin synthesis can result in pigmentation defects, visual deficits, and increased susceptibility to skin and eye cancers. Although genes encoding melanosomal ion-transporters have been identified as key regulators of melanin synthesis, melanosome