Tob38, a novel essential component in the biogenesis of beta-barrel proteins of mitochondria

Thomas Waizenegger, Shukry J Habib, Maciej Lech, Dejana Mokranjac, Stefan A Paschen, Kai Hell, Walter Neupert, Doron Rapaport

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105 Citations (Scopus)


Insertion of beta-barrel proteins into the outer membrane of mitochondria is mediated by the TOB complex. Known constituents of this complex are Tob55 and Mas37. We identified a novel component, Tob38. It is essential for viability of yeast and the function of the TOB complex. Tob38 is exposed on the surface of the mitochondrial outer membrane. It interacts with Mas37 and Tob55 and is associated with Tob55 even in the absence of Mas37. The Tob38-Tob55 core complex binds precursors of beta-barrel proteins and facilitates their insertion into the outer membrane. Depletion of Tob38 results in strongly reduced levels of Tob55 and Mas37 and the residual proteins no longer form a complex. Tob38-depleted mitochondria are deficient in the import of beta-barrel precursor proteins, but not of other outer membrane proteins or proteins of other mitochondrial subcompartments. We conclude that Tob38 has a crucial function in the biogenesis of beta-barrel proteins of mitochondria.
Original languageEnglish
Pages (from-to)704-709
Number of pages6
JournalEMBO Reports
Issue number7
Publication statusPublished - Jul 2004


  • Cell Membrane
  • Cell Proliferation
  • DNA
  • Detergents
  • Dose-Response Relationship, Drug
  • Down-Regulation
  • Electrophoresis, Polyacrylamide Gel
  • Escherichia coli
  • Membrane Proteins
  • Mitochondria
  • Mitochondrial Proteins
  • Open Reading Frames
  • Protein Binding
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • Saccharomyces cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Subcellular Fractions
  • Time Factors


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