ATP-binding cassette sub-family G member 1 is a member of 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. It is involved in macrophage cholesterol and phospholipids transport, and may regulate cellular lipid homeostasis in other cell types. Several alternative splice variants have been identified.The protein sequences of Drosophila W and the predicted 674-amino acid hW protein are 33% identical. By sequencing additional cDNAs and by RT-PCR, Chen et al. (1996) found evidence of alternative splicing.