The ATP-binding cassette (ABC) transporters, or traffic ATPases, constitute an expansive family of proteins accountable for the transport of a wide variety of substrates across cell membranes in both prokaryotic and eukaryotic cells. They also aid in the regulation of lipid transport and membrane trafficking. ABCA12 (ATP-Binding Cassette, Subfamily A, Member 12) contains two transmembrane (TM) domains, each with six membrane-spanning segments, and two nucleotide-binding domains (NBDs), which are located in the cytoplasm. ABCA12 is expressed in normal human keratinocytes (RT-PCR reveals expression in placenta, testis, fetal brain, and skin) and is upregulated during keratinization. Immunoelectron microscopy reveals that the ABCA12 protein is located in lamellar granules in the upper epidermal keratinocytes of human skin. The ABCA12 gene, which synthesizes a 2,595-amino acid protein, may produce an alternative splice variant with an in-frame deletion leading to truncation of 79 amino acids.