SLC45A2 is a transporter protein that mediates melanin synthesis. SLC45A2 is also a melanocyte differentiation antigen that is expressed in a high percentage of melanoma cell lines. A similar sequence gene in medaka, 'B,' encodes a transporter that mediates melanin synthesis. Mutations in this gene are a cause of oculocutaneous albinism type 4. Alternative splicing results in multiple transcript variants encoding different isoforms.In melanocytic cell types, the SLC45A2 gene is regulated by microphthalmia-associated transcription factor.AIM1 gene was expressed in 3 melanoma cell lines, but not in a fibroblast cell line, and not at significant levels in any of 15 normal tissues. The human AIM1 gene encodes a protein of 530 amino acids. Northern blot analysis detected 2 transcripts, one of 1.7 kb and the other of 2.8 kb.