Cellular retinol- and retinoic acid-binding proteins in the epidermis and dermis of normal human skin.

The distribution of cellular retinol- and retinoic acid-binding proteins (CRBP and CRABP) in normal human epidermis and dermis was examined by gel filtration. We showed that CRBP is entirely bound to a lipid-protein aggregate and its free form is obtained through delipidation. The type of homogenization procedure appeared to be important for the recovery of CRBP in human skin. The level of CRABP was about 3.1 pmol/mg protein in the epidermis whereas it was only sporadically detectable in the dermis. In contrast, CRBP was found in both tissues at a concentration of about 1 pmol/mg protein. The difference in CRABP concentrations between epidermis and dermis might have biological and therapeutic implications. Dissociation constants (Kd) of CRABP and CRBP were respectively 2.2 X 10(-7) M and 2.51 X 10(-7) M. This method will facilitate the study of CRABP and CRBP in retinoid- responsive dermatoses and enable us to relate the therapeutic effects of retinoids to the levels of cellular retinoid-binding proteins in the skin.