XENOPUS-LAEVIS CELLULAR RETINOIC ACID-BINDING PROTEIN - TEMPORAL AND SPATIAL EXPRESSION PATTERN DURING EARLY EMBRYOGENESIS

There is increasing evidence that retinoic acid (RA) has a role in est ablishing normal axial patterns during Xenopus laevis embryogenesis. S everal types of retinoid binding proteins are thought to mediate the e ffects of RA. We report the isolation of a cDNA, named xCRABP-b, which encodes a X. laevis cellular retinoic acid-binding protein (xCRABP). This cDNA hybridises to a transcript in gastrular stage embryos of app roximately 3 kb, much larger than those CRABP transcripts expressed in mice. The expression of the xCRABP mRNA is generally restricted to ti ssues which are sensitive to the teratogenic effects of excess RA. It is likely, that during normal X. laevis embryogenesis, concentrations of RA in RA-responsive cells are modulated by the xCRABP gene product.