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  The protein import motor of mitochondria: a targeted molecular ratchet driving unfolding and translocation

Okamoto, K., Brinker, A., Paschen, S. A., Moarefi, I., Hayer-Hartl, M., Neupert, W., et al. (2002). The protein import motor of mitochondria: a targeted molecular ratchet driving unfolding and translocation. EMBO Journal, 21(14), 3659-3671.

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Item Permalink: http://hdl.handle.net/11858/00-001M-0000-0010-6EC0-F Version Permalink: http://hdl.handle.net/11858/00-001M-0000-0010-6EC1-D
Genre: Journal Article
Alternative Title : Embo J.

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 Creators:
Okamoto, K., Author
Brinker, A.1, Author              
Paschen, S. A., Author
Moarefi, I.2, Author              
Hayer-Hartl, M.3, Author              
Neupert, W.1, Author              
Brunner, M., Author
Affiliations:
1External Organizations, ou_persistent22              
2Hartl, Franz-Ulrich / Cellular Biochemistry, Max Planck Institute of Biochemistry, Max Planck Society, ou_1565152              
3Hayer-Hartl, Manajit / Chaperonin-assisted Protein Folding, Max Planck Institute of Biochemistry, Max Planck Society, ou_1565153              

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Free keywords: Brownian ratchet; Hsp70; mitochondria; protein import; unfolding
 Abstract: Unfolding and import of preproteins into mitochondria are facilitated by a molecular motor in which heat shock protein 70 (Hsp70) in the matrix plays an essential role. Here we present two different experimental approaches to analyze mechanisms underlying this function of Hsp70. First, preproteins containing stretches of glutamic acid (polyE) or glycine (polyG) repeats in front of folded domains were imported into mitochondria. This occurred although Hsp70 cannot pull on these stretches to unfold the folded domains, since it does not bind to polyE and polyG. Secondly, preproteins containing titin immunoglobulin (Ig)-like domains were imported into mitochondria, despite the fact that forces of >200 pN are required to mechanically unfold these domains. Since molecular motors generate forces of similar to5 pN, Hsp70 could not promote unfolding of the Ig-like domains by mechanical pulling. Our observations suggest that Hsp70 acts as an element of a Brownian ratchet, which mediates unfolding and translocation of preproteins across the mitochondrial membranes.

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Language(s): eng - English
 Dates: 2002-07-15
 Publication Status: Published in print
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Method: Peer
 Identifiers: eDoc: 41384
ISI: 000176784700011
 Degree: -

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Title: EMBO Journal
  Alternative Title : Embo J.
Source Genre: Journal
 Creator(s):
Affiliations:
Publ. Info: -
Pages: - Volume / Issue: 21 (14) Sequence Number: - Start / End Page: 3659 - 3671 Identifier: ISSN: 0261-4189