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Substance Name: Steroid 17-alpha-Hydroxylase
RN: 9044-50-2


  • A microsomal cytochrome P450 enzyme that catalyzes the 17-alpha-hydroxylation of progesterone or pregnenolone and subsequent cleavage of the residual two carbons at C17 in the presence of molecular oxygen and NADPH-FERRIHEMOPROTEIN REDUCTASE. This enzyme, encoded by CYP17 gene, generates precursors for glucocorticoid, androgen, and estrogen synthesis. Defects in CYP17 gene cause congenital adrenal hyperplasia ( ADRENAL HYPERPLASIA, CONGENITAL) and abnormal sexual differentiation.
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Names and Synonyms

Name of Substance

  • Steroid 17-alpha-Hydroxylase

MeSH Heading

  • Steroid 17-alpha-Hydroxylase


  • 17alpha-Hydroxylase-17,20-lyase
  • C17-C20 lyase
  • Cytochrome CYP17
  • Cytochrome P 450 17
  • Steroid 17-20desmolase

Systematic Name

  • Desmolase, steroid 17-20-

Registry Numbers

CAS Registry Number

  • 9044-50-2

Other Registry Numbers

  • 331947-43-4
  • 9068-00-2

System Generated Number

  • 0009044502