Structure of the gene for the human 17 beta-hydroxysteroid dehydrogenase type IV

The 17 beta-hydroxysteroid dehydrogenase type TV (17 beta-HSD IV) is a mult ifunctional enzyme that is localized in the peroxisomes. The N-terminal par t has dehydrogenase activity, the central part has hydratase activity, and the carboxy-terminal part is responsible for sterol transport. Recent obser vations of mutations in the human 17 beta-HSD IV cDNA leading to a severe p eroxisomal disorder motivated us to define the genomic organization of this gene mapped to Chromosome (Chr) 5q2. We show here that this gene consist o f 24 exons and 23 introns with classical intron-exon junctions spanning mor e than 100 kbp. By mapping the regulatory region of this gene, we have show n that the first 400 bp upstream of the transcription start site are suffic ient to activate transcription. The data presented here will permit sequenc e analysis of patients with peroxisomal disorders.