The adrenoleukodystrophy protein is a member of the ATP-binding cassette transporter superfamily and the ALD subfamily of half transporters that are located in the peroxisome, where they function as homo- and/or heterodimers in the regulation of very long chain fatty acid transport. The exact function of adrenoleukodystrophy protein is unknown, but might be involved in the transport of saturated very long chain fatty acids into the peroxisome by analogy to its yeast homologs Pxa1p and Pxa2p.