Sequences of the swine 21-hydroxylase gene (CYP21) and a portion of the opposite-strand overlapping gene of unknown function previously described in human.

We sequenced a 4.8 kb BamHI swine genomic fragment comprising the entire 21-hydroxylase gene (CYP21) and its 5' and 3' flanking segments. The CYP21 coding sequence spanned 3050 bp and as in other species, comprised 10 exons separated by the corresponding introns. The deduced protein corresponded to 492 amino acid residues, 8 of which differed from a previously sequenced swine CYP21 enzyme. The 5' flanking region displayed several putative cis-acting elements which may be involved in either constitutive or cyclic adenosine 3',5'-monophosphate (cAMP) dependent transcriptional expression. We also characterized within the 5' region a 139 bp repetitive element of the short interspersed nucleotide element (SINE) family located on the opposite strand. In addition, we characterized the last five exons of a human-like opposite strand gene (OSG/X) located in the swine at the 3' end of CYP21. The sequenced part of this OSG/X displayed a very strong homology with its human counterpart.