Protein folding in the cytosol: chaperonin-dependent and -independent mechanisms

Recent findings suggest that a combination of chaperonin-assisted and unassisted mechanisms operate in protein folding in the cytosol. While nascent chain-binding chaperones, such as Hsp70, could have a general role in maintaining the folding competence of translating polypeptide chains, the contrib...

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Bibliographic Details
Published in:Trends in Biochemical Sciences 1998-02, Vol.23 (2), p.68-73
Main Authors: Netzer, William J., Ulrich Hartl, F.
Format: Article
Language:English
Subjects:
Bacterial Proteins - metabolism
Biological Evolution
Chaperonin 60 - metabolism
Chaperonins - metabolism
Cytosol - metabolism
Escherichia coli - metabolism
HSP70 Heat-Shock Proteins - metabolism
Models, Biological
Protein Biosynthesis
Protein Folding
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Summary:Recent findings suggest that a combination of chaperonin-assisted and unassisted mechanisms operate in protein folding in the cytosol. While nascent chain-binding chaperones, such as Hsp70, could have a general role in maintaining the folding competence of translating polypeptide chains, the contribution of the cylindrical chaperonin complexes to overall folding is limited to a subset of aggregation-sensitive polypeptides. The majority of bacterial proteins are relatively small and they are synthesized rapidly and folded independently of the chaperonin GroEL in a posttranslational manner. Eukaryotes have a proportionally larger number of multi-domain proteins than bacteria. The individual domains of these proteins can be folded cotranlationally and sequentially. The use of this mechanism explains how large proteins fold independently of a chaperonin and could have been crucial in the evolution of a wide array of modular polypeptides in eukaryotes.
ISSN:0968-0004
1362-4326
DOI:10.1016/S0968-0004(97)01171-7