Retinol- and retinoic acid-binding proteins: occurrence in human retina and absence from human cultured fibroblasts.

Low-molecular-weight retinol- and retinoic acid-binding proteins were shown to be present in the soluble fraction of human retinal tissue but absent from human fibroblasts grown in tissue culture. By the use of gel filtration and comparison with bovine retinal tissue, the human intracellular binding proteins were found to have molecular weights of approximately 17,000 daltons, which are comparable to the molecular weights of bovine intracellular binding proteins. The quantity of retinoic acid bound exceeded that of retinol by about eightfold.