Could be a melanogenic enzyme. Identified by mass spectrometry in melanosome fractions from stage I to stage IV. May be up-regulated in bone metastatic breast cancer cells. At 9.5-10.5 dpc, highly expressed in the developing eye, restricted to the outer layer of the retina. At midgestation development, expression gets restricted to the forming retinal pigment layer. At 18.5 dpc, expression remains high in the retinal pigment epithelium and is also observed at the forming iris. Belongs to the PMEL/NMB family.