Substrate specificity, gene structure, and tissue-specific distribution of multiple human 3 alpha-hydroxysteroid dehydrogenases.

Article Details

Citation

Khanna M, Qin KN, Wang RW, Cheng KC

Substrate specificity, gene structure, and tissue-specific distribution of multiple human 3 alpha-hydroxysteroid dehydrogenases.

J Biol Chem. 1995 Aug 25;270(34):20162-8.

PubMed ID
7650035 [ View in PubMed
]
Abstract

We have expressed in Escherichia coli functionally active proteins encoded by two human cDNAs that were isolated previously by using rat 3 alpha-hydroxysteroid dehydrogenase cDNA as the probe. The expressed proteins catalyzed the interconversion between 5 alpha-dihydrotestosterone and 5 alpha-androstane-3 alpha,17 beta-diol. Therefore, we name these two enzymes type I and type II 3 alpha-hydroxysteroid dehydrogenases. The type I enzyme has a high affinity for dihydrotestosterone, whereas the type II enzyme has a low affinity for the substrate. The tissue-specific distribution of these two enzymes was determined by reverse transcription polymerase chain reaction using gene-specific oligonucleotide primers. The mRNA transcript of the type I enzyme was found only in the liver, whereas that of the type II enzyme appeared in the brain, kidney, liver, lung, placenta, and testis. The structure and sequence of the genes encoding these two 3 alpha-hydroxysteroid dehydrogenases were determined by analysis of genomic clones that were isolated from a lambda EMBL3 SP6/T7 library. The genes coding for the type I and type II enzymes were found to span approximately 20 and 16 kilobase pairs, respectively, and to consist of 9 exons of the same sizes and boundaries. The exons range in size from 77 to 223 base pairs (bp), whereas the introns range in size from 375 bp to approximately 6 kilobase pairs. The type I gene contains a TATA box that is located 27 bp upstream of multiple transcription start sites. In contrast, the type II gene contains two tandem AP2 sequences juxtaposed to a single transcription start site.

DrugBank Data that Cites this Article

Polypeptides
NameUniProt ID
Aldo-keto reductase family 1 member C4P17516Details
Aldo-keto reductase family 1 member C3P42330Details