Cellular retinol-binding protein (CRBP) has been purified to homogeneity from normal human liver. The procedures in the purification involved primarily gel filtration and ion exchange chromatography, resulting in a 3000-fold purification with greater than 40% yield. The protein is a single polypeptide chain with molecular weight of 14,800. The protein binds retinol in a manner which considerably alters its spectrum from that observed in organic solution. Many of the properties of human CRBP including molecular weight, amino acid composition, and spectrum of bound retinol are similar to those observed previously for rat CRBP. The availability of pure human CRBP should aid in elucidating its role in the action of retinol and also in more easily monitoring the considerable changes in level of this protein reported in some human cancers.
This work was supported by USPHS Grant CA-20950.