Structure of two in tandem human 17β-hydroxysteroid dehydrogenase genes

Abstract

Two human 17β-hydroxysteroid dehydrogenase (17beta;-HSD) genes (h17beta;-HSDI and h17beta;-HSDII) included in tandem within an approximately 13 kilobase pair fragment were isolated from a genomic λEMBL3 DNA library using cDNA encoding human 17beta;-HSD (hpE2DH216) as probe. We have determined the complete exon and intron sequences of the two genes as well as their 5′ and 3′-flanking regions. Human 17beta;-HSDII contains six exons and five short introns for a total length of 3250 base pairs. The exon sequence of h17beta;-HSDII is identical to the previously reported hpE2DH216 cDNA while the overlapping nucleotide sequences of the corresponding exons and introns of h17beta;-HSDI and h17beta;-HSDII show 89% homology. In addition, we have used the hpE2DH216 cDNA to demonstrate the widespread expression of 17beta;-HSD mRNAs in steroidogenic and peripheral target tissues. These new findings provide the basis for a better understanding of the molecular mechanisms involved in 17beta;-HSD deficiency and peripheral sex steroid metabolism.