Associates with STAR2 to form a functional transmembrane ABC transporter required for detoxification of aluminum (Al) in roots. Can specifically transport UDP-glucose. Interacts with STAR2. Expressed in roots. By Al in roots. Positively regulated by ART1. No visible phenotype under normal growth condition, but strong inhibition of root elongation when grown in the presence of Al or on acidic soil. Belongs to the ABC transporter superfamily. ABCI family. Truncated N-terminus.