The protein import motor of mitochondria

Nat Rev Mol Cell Biol. 2002 Aug;3(8):555-65. doi: 10.1038/nrm878.


Proteins that are destined for the matrix of mitochondria are transported into this organelle by two translocases: the TOM complex, which transports proteins across the outer mitochondrial membrane; and the TIM23 complex, which gets them through the inner mitochondrial membrane. Two models have been proposed to explain how this protein-import machinery works -- a targeted Brownian ratchet, in which random motion is translated into vectorial motion, or a 'power stroke', which is exerted by a component of the import machinery. Here, we review the data for and against each model.

Publication types

  • Review

MeSH terms

  • Membrane Proteins / metabolism
  • Membrane Transport Proteins / metabolism
  • Mitochondria / metabolism*
  • Models, Biological
  • Molecular Motor Proteins / metabolism*
  • Protein Conformation
  • Protein Folding
  • Protein Transport / physiology*
  • Saccharomyces cerevisiae Proteins / metabolism


  • Membrane Proteins
  • Membrane Transport Proteins
  • Molecular Motor Proteins
  • Saccharomyces cerevisiae Proteins
  • TIM23 protein, S cerevisiae