Tim18p is a new component of the Tim54p-Tim22p translocon in the mitochondrial inner membrane

Oliver Kerscher, Naresh B. Sepuri, Robert E. Jensen

Research output: Contribution to journalArticle


The mitochondrial inner membrane contains two separate translocons: one required for the translocation of matrix-targeted proteins (the Tim23p-Tim17p complex) and one for the insertion of polytopic proteins into the mitochondrial inner membrane (the Tim54p-Tim22p complex). To identify new members of the Tim54p-Tim22p complex, we screened for high-copy suppressors of the temperature-sensitive tim54-1 mutant. We identified a new gene, TIM18, that encodes an integral protein of the inner membrane. The following genetic and biochemical observations suggest that the Tim18 protein is part of the Tim54p-Tim22p complex in the inner membrane: multiple copies of TIM18 suppress the tim54-1 growth defect; the tim18::HIS3 disruption is synthetically lethal with tim54-1; Tim54p and Tim22p can be coimmune precipitated with the Tim18 protein; and Tim18p, along with Tim54p and Tim22p, is detected in an ~300-kDa complex after blue native electrophoresis. We propose that Tim18p is a new component of the Tim54pTim22p machinery that facilitates insertion of polytopic proteins into the mitochondrial inner membrane.

Original languageEnglish (US)
Pages (from-to)103-116
Number of pages14
JournalMolecular biology of the cell
Issue number1
StatePublished - Jan 2000


ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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