A mitochondrial import factor purified from rat liver cytosol is an ATP-dependent conformational modulator for precursor proteins

N. Hachiya, R. Alam, Y. Sakasegawa, M. Sakaguchi, K. Mihara, T. Omura

Research output: Contribution to journalArticlepeer-review

131 Citations (Scopus)

Abstract

Rat liver cytosol contained an activity that stimulated the import of wheat germ lysate-synthesized precursor proteins into mitochondria, The activity was purified 10 000-fold from the cytosol as a homogeneous heterodimeric protein. This protein (termed mitochondrial import stimulation factor or MSF) stimulated the binding and import of mitochondrial precursor proteins. MSF was also found to recognize the presequence portion of mitochondrial precusors and catalyze the depolymerization and unfolding of in vitro synthesized mitochondrial precursor proteins in an ATP-dependent manner; in this connection, MSF exhibited ATPase activity depending on the import-incompetent mitochondrial precursor protein. The mitochondrial binding and import-stimulating activities were strongly inhibited by the pretreatment of MSF with NEM, whereas the ATP-dependent depolymerization activity was insensitive to the NEM treatment, suggesting that the process subsequent to the unfolding was inhibited with the NEM treatment. We conclude that MSF is a multifunctional cytoplasmic chaperone specific for mitochondrial protein import.

Original languageEnglish
Pages (from-to)1579-1586
Number of pages8
JournalEMBO Journal
Volume12
Issue number4
DOIs
Publication statusPublished - 1993

Keywords

  • Adrenodoxin precursor
  • Chaperone
  • Cytosolic factor
  • Mitochondrial protein import
  • Rat liver mitochondria

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)

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