RBP7 is a member of a superfamily of small cytoplasmic proteins which interact with hydrophobic ligands. RBP7 is cytoplasmic protein which,like CRBP I and CRBP II,forms ?-barrel structures and participates in the intracellular transport of retinol. RBP7 is a newly identified cellular retinol carrier,which is expressed in the kidney,heart and transverse colon in humans.