ATP Binding Cassette Transporter G4 (ABCG4)

ATP-binding cassette sub-family G member 4 is a protein included in the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White).This protein is a member of the White subfamily and is expressed predominantly in liver tissue. The function has not yet been determined but may involve cholesterol transport. Alternate splice variants have been described but their full length sequences have not been determined. Engel et al. (2001) demonstrated 5-fold induction of ABCG4 following treatment of normal monocyte-derived macrophages with the LXR and RXR agonists 9-cis retinoic acid and 22R hydroxycholesterol.