ABCG1 (also designated ABC8 or human white gene), a member of the evolutionary conserved family of ATP-binding cassette (ABC) transporters, exhibits high homology with the Drosophila white gene. ABC transporters couple the energy of ATP hydrolysis to the translocation of various molecules across biological membranes. These proteins contain characteristic ATP-binding domains and transmembrane domains which form a channel-like structure for transport. ABCG1 functions to regulate cholesterol and phospholipid transport in macrophages. ABCG1 is highly expressed in several tissues, including brain, spleen, lung and placenta, and has been localized to the cell surface and intracellular compartments of cholesterol-laden macrophages.
