Structural and biochemical properties of cloned and expressed human and rat steroid 5α-reductases

Stefan Andersson, David W. Russell

Research output: Contribution to journalArticlepeer-review

497 Scopus citations


The microsomal enzyme steroid 5α-reductase is responsible for the conversion of testosterone into the more potent androgen dihydrotestosterone. In man, this steroid acts on a variety of androgen-responsive target tissues to mediate such diverse endocrine processes as male sexual differentiation in the fetus and prostatic growth in men. Here we describe the isolation, structure, and expression of a cDNA encoding the human steroid 5α-reductase. A rat cDNA was used as a hybridization probe to screen a human prostate cDNA library. A 2.1-kilobase cDNA was identified and DNA sequence analysis indicated that the human steroid 5α-reductase was a hydrophobic protein of 259 amino acids with a predicted molecular weight of 29,462. A comparison of the human and rat protein sequences revealed a 60% identity. Transfection of expression vectors containing the human and rat cDNAs into simian COS cells resulted in the synthesis of high levels of steroid 5α-reductase enzyme activity. Both enzymes expressed in COS cells showed similar substrate specificities for naturally occurring steroid hormones. However, synthetic 4-azasteroids demonstrated marked differences in their abilities to inhibit the human and rat steroid 5α-reductases. (.

Original languageEnglish (US)
Pages (from-to)3640-3644
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number10
StatePublished - 1990


  • 4-azasteroid inhibitors
  • Androgen metabolism
  • Benign prostate hyperplasia
  • Dihydrotestosterone
  • cDNA

ASJC Scopus subject areas

  • General


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