Conservation of function between mammalian and plant steroid 5alpha-reductases

Proc Natl Acad Sci U S A. 1997 Apr 15;94(8):3554-9. doi: 10.1073/pnas.94.8.3554.


Arabidopsis det2 mutants are small dark-green dwarfs displaying pleiotropic defects in light-regulated development during multiple stages of the plant life cycle. The DET2 gene encodes a protein that shares approximately 40% sequence identity with mammalian steroid 5alpha-reductases and is implicated in the synthesis of a class of plant steroids, the brassinosteroids. Here we show that the DET2 protein, when expressed in human embryonic kidney 293 cells, catalyzes the 5alpha-reduction of several animal steroid substrates and has similar kinetic properties to the mammalian steroid 5alpha-reductase enzymes. Moreover, human steroid 5alpha-reductases expressed in det2 mutant plants can substitute for DET2 in brassinosteroid biosynthesis. These data indicate that DET2 is an ortholog of the mammalian steroid 5alpha-reductases and provide further evidence that brassinosteroids play an essential role in light-regulated plant development. The structural and functional conservation between DET2 and human steroid 5alpha-reductases raise interesting issues concerning the evolutionary origin of the steroid hormone signaling system.

Publication types

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

MeSH terms

  • 3-Oxo-5-alpha-Steroid 4-Dehydrogenase / genetics*
  • Animals
  • Arabidopsis Proteins*
  • DNA, Complementary / genetics
  • Evolution, Molecular*
  • Humans
  • Mammals
  • Mutation
  • Plant Proteins / genetics*
  • Plants
  • Plants, Genetically Modified


  • Arabidopsis Proteins
  • DET2 protein, Arabidopsis
  • DNA, Complementary
  • Plant Proteins
  • 3-Oxo-5-alpha-Steroid 4-Dehydrogenase