A common ancestor for a subunit in the mitochondrial proton-translocating NADH:ubiquinone oxidoreductase (complex I) and short-chain dehydrogenases/reductases

Cell Mol Life Sci. 1999 Mar;55(3):450-5. doi: 10.1007/s000180050301.


The proton-translocating NADH:ubiquinone oxidoreductase or complex I is located in the inner membranes of mitochondria, where it catalyzes the transfer of electrons from NADH to ubiquinone. Here we report that one of the subunits in complex I is homologous to short-chain dehydrogenases and reductases, a family of enzymes with diverse activities that include metabolizing steroids, prostaglandins and nucleotide sugars. We discovered that a subunit of complex I in human, cow, Neurospora crassa and Aquifex aeolius is homologous to nucleotide-sugar epimerases and hydroxysteroid dehydrogenases while seeking distant homologs of these enzymes with a hidden Markov model-based search of Genpept. This homology allows us to use information from the solved three-dimensional structures of nucleotide-sugar epimerases and hydroxysteroid dehydrogenases and our motif analysis of these enzymes to predict functional domains on their homologs in complex I.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics
  • Cattle
  • Evolution, Molecular
  • Fungal Proteins / chemistry
  • Fungal Proteins / genetics
  • Gram-Negative Aerobic Rods and Cocci / enzymology
  • Gram-Negative Aerobic Rods and Cocci / genetics
  • Humans
  • Hydroxysteroid Dehydrogenases / chemistry
  • Hydroxysteroid Dehydrogenases / genetics
  • Markov Chains
  • Molecular Sequence Data
  • Multigene Family
  • NAD(P)H Dehydrogenase (Quinone) / chemistry
  • NAD(P)H Dehydrogenase (Quinone) / genetics*
  • Neurospora crassa / enzymology
  • Neurospora crassa / genetics
  • Oxidoreductases / chemistry
  • Oxidoreductases / genetics*
  • Sequence Alignment
  • Sequence Homology, Amino Acid
  • Software


  • Bacterial Proteins
  • Fungal Proteins
  • Oxidoreductases
  • Hydroxysteroid Dehydrogenases
  • NAD(P)H Dehydrogenase (Quinone)