Steroid 5α reductase in cultured human fibroblasts. Biochemical and genetic evidence for two distinct enzyme activities

R. J. Moore, J. D. Wilson

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Various properties of the steroid 5α reductase have been examined in cell free extracts of skin and of fibroblasts cultured from genital and nongenital skins from control subjects and from patients with several forms of male pseudohermaphroditism. When 20α hydroxy 4 [1,2 3H] pregnen 3 one was used as substrate, two 5α reductase activities could be demonstrated in intact skin and cultured fibroblasts. The major activity, previously described for microsomes from human prepuce and extracts of cultured foreskin fibroblasts, is characterized by a narrow pH optimum near 5.5 and is limited to fibroblasts derived from genital skin. A second activity, not limited by the site of biopsy, has been demonstrated over a higher and broader range of pH (from 7 to 9); this enzyme activity is found in both genital and nongenital skin and in fibroblasts cultured from all skin regions. Whereas there is wide variability in the activity at pH 5.5 in genital skin fibroblasts, the activity at pH 7 to 9 is similar in fibroblasts derived from all anatomical sites. The two activities exhibit different kinetics with respect to steroid substrate and are also dissimilar in their subcellular distributions. Other properties, such as coenzyme requirement, steroid substrate specificity, and instability with increasing temperature, appear to be similar.

Original languageEnglish (US)
Pages (from-to)5895-5900
Number of pages6
JournalJournal of Biological Chemistry
Issue number19
StatePublished - Jan 1 1976


ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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