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Polypeptides traverse the mitochondrial envelope in an extended state
Author(s) -
Rassow Joachim,
Hartl Franz-Ulrich,
Guiard Bernard,
Pfanner Nikolaus,
Neupert Walter
Publication year - 1990
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(90)81469-5
Subject(s) - cytosol , mitochondrion , membrane , biochemistry , inner mitochondrial membrane , mitochondrial membrane transport protein , dihydrofolate reductase , mitochondrial carrier , inner membrane , cytochrome c , chromosomal translocation , biology , translocase of the inner membrane , translocase of the outer membrane , amino acid , chemistry , biophysics , microbiology and biotechnology , bacterial outer membrane , enzyme , gene , escherichia coli
Most mitochondrial proteins are synthesized as precursors in the cytosol and imported through the contact sites between outer and inner mitochondrial membranes. The molecular mechanism of membrane translocation of precursor proteins is largely unclear. For this report, various hybrid proteins between portions of the precursor of cytochrome b 2 and the entire dihydrofolate reductase (DHFR) were accumulated in mitochondrial contact sites. We unexpectedly found that about 30 amino acid residues of the polypeptide chain in transit were sufficient to span both membranes. This suggests linear translocation of the polypeptide chain and presents evidence for a high degree of unfolding of polypeptides traversing the mitochondrial membranes.