GTP hydrolysis is essential for protein import into the mitochondrial matrix

Naresh Babu V. Sepuri, Norbert Schülke, Debkumar Pain

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31 Scopus citations


Protein import into the innermost compartment of mitochondria (the matrix) requires a membrane potential (ΔΨ) across the inner membrane, as well as ATP-dependent interactions with chaperones in the matrix and cytosol. The role of nucleoside triphosphates other than ATP during import into the matrix, however, remains to be determined. Import of urea-denatured precursors does not require cytosolic chaperones. We have therefore used a purified and urea-denatured preprotein in our import assays to bypass the requirement of external ATP. Using this modified system, we demonstrate that GTP stimulates protein import into the matrix; the stimulatory effect is directly mediated by GTP hydrolysis and does not result from conversion of GTP to ATP. Both external GTP and matrix ATP are necessary; neither one can substitute for the other if efficient import is to be achieved. These results suggest a 'push-pull' mechanism of import, which may be common to other posttranslational translocation pathways.

Original languageEnglish (US)
Pages (from-to)1420-1424
Number of pages5
JournalJournal of Biological Chemistry
Issue number3
StatePublished - Jan 16 1998
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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