Tim22, the essential core of the mitochondrial protein insertion complex, forms a voltage-activated and signal-gated channel

Peter Kovermann, Kaye N. Truscott, Bernard Guiard, Peter Rehling, Naresh B. Sepuri, Hanne Müller, Robert E. Jensen, Richard Wagner, Nikolaus Pfanner

Research output: Contribution to journalArticlepeer-review

Abstract

The protein insertion complex of the mitochondrial inner membrane is crucial for import of the numerous multitopic membrane proteins with internal targeting signals. Little is known about the molecular mechanism of this complex, including whether it forms a real channel or merely acts as scaffold for protein insertion. We report the unexpected observation that Tim22 is the only essential membrane-integrated subunit of the complex. Reconstituted Tim22 forms a hydrophilic, high-conductance channel with distinct opening states and pore diameters. The channel is voltage-activated and specifically responds to an internal targeting signal, but not to presequences. Thus, a protein insertion complex can combine three essential functions, signal recognition, channel formation, and energy transduction, in one central component.

Original languageEnglish (US)
Pages (from-to)363-373
Number of pages11
JournalMolecular cell
Volume9
Issue number2
DOIs
StatePublished - 2002

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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