The membrane-associated 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 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 MDR TAP subfamily Members of the MDR TAP subfamily are involved in multidrug resistance This gene is located 7 kb telomeric to gene family member ABCB2 The protein encoded by this gene is involved in antigen presentation This protein forms a heterodimer with ABCB2 in order to transport peptides from the cytoplasm to the endoplasmic reticulum Mutations in this gene may be associated with ankylosing spondylitis insulin-dependent diabetes mellitus and celiac disease Alternative splicing of this gene produces products which differ in peptide selectivity and level of restoration of surface expression of MHC class I molecules