The protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intracellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the ABC1 subfamily. Members of the ABC1 subfamily comprise the only major ABC subfamily found exclusively in multicellular eukaryotes. This protein is widely expressed with highest detection in spleen and hematopoietic tissues. Defects in this gene cause an increase in amyloid-beta deposits in a mouse model of Alzheimer's disease, and a related human protein is thought to play a role in lipid homeostasis in cells of the immune system. [provided by RefSeq, Jan 2017]