Calcium, potassium:sodium antiporter that transports 1 Ca(2+) and 1 K(+) to the melanosome in exchange for 4 cytoplasmic Na(+) (By similarity). Involved in pigmentation, possibly by participating in ion transport in melanosomes (PubMed:16357253). Predominant sodium-calcium exchanger in melanocytes (PubMed:16357253). Ca(2+)(out) + K(+)(out) + 4 Na(+)(in) = Ca(2+)(in) + K(+)(in) + 4 Na(+)(out) Enriched in late-stage melanosomes. Highly expressed in melanin-producing cells. Colocalizes with melanin biosynthesis marker dct. Expressed in the retinal pigment epithelium and in the melanopore precursors at 1 day post-fertilization. Fishes show a delayed and reduced development of pigmentation. They display a diminished number, size and density of melanosomes. Belongs to the Ca(2+):cation antiporter (CaCA) (TC 2.A.19) family. SLC24A subfamily. Skin-deep - Issue 74 of September 2006