| Modification Notes |
ABCG5 (also designated Sterolin-1) is a member of the evolutionarily conserved family of ATP-binding cassette (ABC) transporters. ABC transporters couple the energy of ATP hydrolysis to the translocation of various molecules across biological membranes. These proteins contain characteristic ATP-binding domains at the amino-terminus and a transmembrane domain in the carboxy-terminus, which forms a channel-like structure for transport. The ABCG5 gene maps to human chromosome 2p21 and is highly expressed in liver and intestine. ABCG5 and a highly homologous gene, ABCG8 (also designated Sterolin-2), are thought to regulate the uptake of dietary cholesterol and block the absorption of plant and shellfish sterols. Mutations in either ABCG5 or ABCG8 lead to sitosterolemia, a rare autosomal recessive disorder characterized by hyperabsorption of all sterols, including cholesterol and plant and shellfish sterols. Patients with this disease are hypercholesterolemic and frequently develop xanthomas, accelerated atherosclerosis and premature coronary artery disease. Therefore, ABCG5 is a critical component of the sterol transport pathway. |