This gene encodes a member of the ATP-binding cassette (ABC) transporter superfamily. ABC proteins transport various molecules across extra- and intra-cellular membranes. This protein is a member of the heavy metal importer subfamily and plays a role in porphyrin transport. This gene is the molecular basis of the Langereis (Lan) blood group antigen and mutations in this gene underlie familial pseudohyperkalemia and dyschromatosis universalis hereditaria. [provided by RefSeq, Mar 2017].