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

Proc Natl Acad Sci U S A. 1990 May;87(10):3640-4. doi: 10.1073/pnas.87.10.3640.

Abstract

The microsomal enzyme steroid 5 alpha-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 5 alpha-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 5 alpha-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 5 alpha-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 5 alpha-reductases.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 3-Oxo-5-alpha-Steroid 4-Dehydrogenase / genetics*
  • 3-Oxo-5-alpha-Steroid 4-Dehydrogenase / metabolism
  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Cell Line
  • Cloning, Molecular
  • DNA / genetics
  • Gene Expression
  • Genetic Vectors
  • Humans
  • Kinetics
  • Molecular Sequence Data
  • Oligonucleotide Probes
  • Polymerase Chain Reaction
  • Rats
  • Sequence Homology, Nucleic Acid
  • Substrate Specificity
  • Transfection

Substances

  • Oligonucleotide Probes
  • DNA
  • 3-Oxo-5-alpha-Steroid 4-Dehydrogenase

Associated data

  • GENBANK/M32313