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Mgr2 promotes coupling of the mitochondrial presequence translocase to partner complexes.

Many mitochondrial proteins are synthesized with N-terminal presequences in the cytosol. The presequence translocase of the inner mitochondrial membrane (TIM23) translocates preproteins into and across the membrane and associates with the matrix-localized import motor. The TIM23 complex consists of three core components and Tim21, which interacts with the translocase of the outer membrane (TOM) and the respiratory chain. We have identified a new subunit of the TIM23 complex, the inner membrane protein Mgr2. Mitochondria lacking Mgr2 were deficient in the Tim21-containing sorting form of the TIM23 complex. Mgr2 was required for binding of Tim21 to TIM23(CORE), revealing a binding chain of TIM23(CORE)-Mgr2/Tim21-respiratory chain. Mgr2-deficient yeast cells were defective in growth at elevated temperature, and the mitochondria were impaired in TOM-TIM23 coupling and the import of presequence-carrying preproteins. We conclude that Mgr2 is a coupling factor of the presequence translocase crucial for cell growth at elevated temperature and for efficient protein import.

Pubmed ID: 22613836


  • Gebert M
  • Schrempp SG
  • Mehnert CS
  • HeiƟwolf AK
  • Oeljeklaus S
  • Ieva R
  • Bohnert M
  • von der Malsburg K
  • Wiese S
  • Kleinschroth T
  • Hunte C
  • Meyer HE
  • Haferkamp I
  • Guiard B
  • Warscheid B
  • Pfanner N
  • van der Laan M


The Journal of cell biology

Publication Data

May 28, 2012

Associated Grants


Mesh Terms

  • Cell Proliferation
  • Membrane Proteins
  • Membrane Transport Proteins
  • Mitochondrial Membrane Transport Proteins
  • Multiprotein Complexes
  • Protein Subunits
  • Protein Transport
  • Saccharomyces cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Temperature