Protein translocation into mitochondria: the role of TIM complexes

Trends Cell Biol. 2000 Jan;10(1):25-31. doi: 10.1016/s0962-8924(99)01684-0.


Import of nuclear-encoded mitochondrial preproteins is mediated by a general translocase in the outer membrane, the TOM complex, and by two distinct translocases in the mitochondrial inner membrane, the TIM23 complex and the TIM22 complex. Both TIM complexes cooperate with the TOM complex but facilitate import of different classes of precursor proteins. Precursors with an N-terminal presequence are imported via the TIM23 complex, whereas mitochondrial carrier proteins require the TIM22 complex for insertion into the inner membrane. This review discusses recent advances in understanding the structure and function of the translocases of the inner membrane and the possible role of Tim proteins in the development of the Mohr-Tranebjaerg syndrome, a mitochondrial disorder leading to neurodegeneration.

Publication types

  • Review

MeSH terms

  • Animals
  • Biological Transport
  • Carrier Proteins*
  • Humans
  • Membrane Proteins*
  • Membrane Transport Proteins*
  • Mitochondria / physiology*
  • Mitochondrial Membrane Transport Proteins
  • Mitochondrial Myopathies
  • Saccharomyces cerevisiae Proteins*


  • Carrier Proteins
  • Membrane Proteins
  • Membrane Transport Proteins
  • Mitochondrial Membrane Transport Proteins
  • Saccharomyces cerevisiae Proteins
  • TIM22 protein, S cerevisiae
  • TIM23 protein, S cerevisiae