UNIQUE TISSUE DISTRIBUTION OF 2 DISTINCT CELLULAR RETINOIC ACID BINDING-PROTEINS IN NEONATAL AND ADULT-RAT

Two different species of cellular retinoic acid binding proteins, CRABP-I and CRABP-II, have been found in neonatal rat pups. In this report, we describe a sensitive radio-ligand binding assay for CRABP in crude tissue extracts. The assay makes use of anion-exchange high-pressure liquid chromatography which effectively separates CRABP-II from CRABP-I, thus permitting the simultaneous quantitation of these two proteins. The distribution CRABP-I and CRABP-II in various neonatal and adult tissues of the rat has been examined. CRABP-I is the predominant species of CRABP and is present in high levels in the brain, skin and testis. CRABP-II is apparently unique to the skin of neonatal animals and it becomes undetectable in adult skin. Interestingly, CRABP-II is detected at a significant level only in the adrenals of adult animals, while neonatal adrenals express only CRABP-I and not CRABP-II. CRABP-I in present in higher levels in most organs at the neonatal stage than in the adult. © 1990.