Developmental expression pattern of Stra6, a retinoic acid-responsive gene encoding a new type of membrane protein.

Retinoic acid plays important roles in development, growth and differentiation by regulating the expression of target genes. A new retinoic acid-inducible gene, Stra6, has been identified in P19 embryonal carcinoma cells using a subtractive hybridization cDNA cloning technique. Stra6 codes for a very hydrophobic membrane protein of a new type, which does not display similarities with previously characterized integral membrane proteins. Stra6, which exhibits a specific pattern of expression during development and in the adult, is strongly expressed at the level of blood-organ barriers. Interestingly, in testis Sertoli cells, Stra6 has a spermatogenic cycle-dependent expression which is lost in testes of RAR alpha null mutants where Stra6 is expressed in all tubules. We suggest that the Stra6 protein may be a component of an as yet unidentified transport machinery.