A presequence- and voltage-sensitive channel of the mitochondrial preprotein translocase formed by Tim23

Nat Struct Biol. 2001 Dec;8(12):1074-82. doi: 10.1038/nsb726.

Abstract

Proteins imported into the mitochondrial matrix are synthesized in the cytosol with an N-terminal presequence and are translocated through hetero-oligomeric translocase complexes of the outer and inner mitochondrial membranes. The channel across the inner membrane is formed by the presequence translocase, which consists of roughly six distinct subunits; however, it is not known which subunits actually form the channel. Here we report that purified Tim23 forms a hydrophilic, approximately 13-24 A wide channel characteristic of the mitochondrial presequence translocase. The Tim23 channel is cation selective and activated by a membrane potential and presequences. The channel is formed by the C-terminal domain of Tim23 alone, whereas the N-terminal domain is required for selectivity and a high-affinity presequence interaction. Thus, Tim23 forms a voltage-sensitive high-conductance channel with specificity for mitochondrial presequences.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carrier Proteins / chemistry
  • Carrier Proteins / metabolism
  • Electrophysiology
  • Intracellular Membranes / chemistry
  • Intracellular Membranes / enzymology
  • Intracellular Membranes / metabolism
  • Ion Channel Gating*
  • Lipid Bilayers / chemistry
  • Lipid Bilayers / metabolism
  • Liposomes / chemistry
  • Liposomes / metabolism
  • Macromolecular Substances
  • Membrane Potentials
  • Membrane Proteins / chemistry
  • Membrane Proteins / metabolism
  • Membrane Transport Proteins / chemistry*
  • Membrane Transport Proteins / genetics
  • Membrane Transport Proteins / metabolism*
  • Mitochondria / chemistry*
  • Mitochondria / enzymology
  • Mitochondria / genetics
  • Mitochondria / metabolism*
  • Mitochondrial Membrane Transport Proteins*
  • Mutation / genetics
  • Permeability
  • Protein Binding
  • Protein Precursors / chemistry
  • Protein Precursors / metabolism*
  • Protein Sorting Signals / physiology*
  • Protein Structure, Quaternary
  • Protein Structure, Tertiary
  • Protein Subunits
  • Protein Transport
  • Repressor Proteins*
  • Saccharomyces cerevisiae / cytology
  • Saccharomyces cerevisiae / enzymology
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins / chemistry*
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Substrate Specificity

Substances

  • Carrier Proteins
  • Lipid Bilayers
  • Liposomes
  • Macromolecular Substances
  • Membrane Proteins
  • Membrane Transport Proteins
  • Mitochondrial Membrane Transport Proteins
  • Protein Precursors
  • Protein Sorting Signals
  • Protein Subunits
  • Repressor Proteins
  • Saccharomyces cerevisiae Proteins
  • TIM17 protein, S cerevisiae
  • TIM23 protein, S cerevisiae
  • TIM44 protein, S cerevisiae