Structural basis of presequence recognition by the mitochondrial protein import receptor Tom20

Cell. 2000 Mar 3;100(5):551-60. doi: 10.1016/s0092-8674(00)80691-1.


Most mitochondrial proteins are synthesized in the cytosol as precursor proteins with a cleavable N-terminal presequence and are imported into mitochondria. We report here the NMR structure of a general import receptor, rat Tom20, in a complex with a presequence peptide derived from rat aldehyde dehydrogenase. The cytosolic domain of Tom20 forms an all alpha-helical structure with a groove to accommodate the presequence peptide. The bound presequence forms an amphiphilic helical structure with hydrophobic leucines aligned on one side to interact with a hydrophobic patch in the Tom20 groove. Although the positive charges of the presequence are essential for import ability, presequence binding to Tom20 is mediated mainly by hydrophobic rather than ionic interactions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aldehyde Dehydrogenase / metabolism
  • Amino Acid Sequence
  • Amino Acid Substitution
  • Animals
  • Biological Transport
  • Chemical Phenomena
  • Chemistry, Physical
  • Fungal Proteins / chemistry
  • Macromolecular Substances
  • Magnetic Resonance Spectroscopy
  • Membrane Proteins / chemistry
  • Membrane Proteins / physiology*
  • Membrane Transport Proteins*
  • Mitochondria / metabolism*
  • Mitochondrial Precursor Protein Import Complex Proteins
  • Models, Molecular
  • Molecular Sequence Data
  • Protein Binding
  • Protein Conformation
  • Protein Sorting Signals / chemistry
  • Protein Sorting Signals / metabolism
  • Rats
  • Receptors, Cell Surface*
  • Recombinant Fusion Proteins / metabolism
  • Sequence Alignment
  • Sequence Homology, Amino Acid
  • Species Specificity
  • Structure-Activity Relationship


  • Fungal Proteins
  • Macromolecular Substances
  • Membrane Proteins
  • Membrane Transport Proteins
  • Mitochondrial Precursor Protein Import Complex Proteins
  • Protein Sorting Signals
  • Receptors, Cell Surface
  • Recombinant Fusion Proteins
  • Tomm20 protein, rat
  • Aldehyde Dehydrogenase

Associated data

  • PDB/1OM2