Mono Q HR 5/5 FPLC anion exchange elution profile of RBPs following fractionation by Sephadex G-75 gel filtration and Superose 12 HR 10/30 FPLC. The column was washed with 50 mM Tris-HCl, 1 mM dithiothreitol (pH 8.0) and eluted with 1 M NaCl in the wash buffer. A 0-0.5 M NaCl gradient, 0.5 ml/min flow rate, 0.1 AUFS and 0.5 cm/min chart speed were used. Retinol-binding proteins were separated into two major fractions, 1 and 2.