EXPRESSION OF 4-ALPHA-CARBINOLAMINE DEHYDRATASE IN HUMAN EPIDERMAL-KERATINOCYTES

4 alpha-Carbinolamine dehydratase is a bifunctional protein involved i n the regeneration of tetrahydrobiopterin during the hydroxylation of the aromatic amino acids. It is also a dimerization cofactor of HNF1 a nd therefore is believed to function as part of the hepatic gene trans cription system. In view of the recent discoveries that the distributi on and developmental pattern of the dehydratase do not correlate stric tly with those of the aromatic amino acid hydroxylases and HNF1, the h ypothesis that the dehydratase may have other unknown functions has be en put forward. In the present paper, we demonstrate unambiguously tha t human epidermal keratinocytes express detectable levels of this prot ein as indicated by enzyme assay, immunoprecipitation, Western blot, a nd RT-PCR. Its complete coding sequence has been cloned and was found to be identical with the human liver counterpart. The possible functio n of the dehydratase in skin is discussed. (C) 1997 Academic Press.