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Related Concept Videos

Molecular Chaperones and Protein Folding03:00

Molecular Chaperones and Protein Folding

17.9K
The native conformation of a protein is formed by interactions between the side chains of its constituent amino acids. When the amino acids cannot form these interactions, the protein cannot fold by itself and needs chaperones. Notably, chaperones do not relay any additional information required for the folding of polypeptides; the native conformation of a protein is determined solely by its amino acid sequence. Chaperones catalyze protein folding without being a part of the folded protein.
The...
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Protein Folding Quality Check in the RER01:29

Protein Folding Quality Check in the RER

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ER is the primary site for the maturation and folding of soluble and transmembrane secretory proteins. The calnexin cycle is a specific chaperone system that folds and assesses the confirmation of N-glycosylated proteins before they can exit the ER lumen. The primary players of this quality check pipeline are the lectins, ER-resident chaperones, and a glucosyl transferase enzyme. In case the calnexin system in the lumen fails to salvage a misfolded protein, it is transported to the cytoplasm...
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Post-translational Translocation of Proteins to the RER01:27

Post-translational Translocation of Proteins to the RER

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A sizable fraction of proteins destined for ER are first synthesized in the cell cytosol and then transported across the ER membrane–a process called post-translational translocation. Similar to cotranslationally translocated proteins, these proteins also use the Sec translocon complex to enter the ER lumen.
Targeting proteins to the ER
Hsp40 and Hsp70 chaperone molecules bind the translated proteins in the cytosol to prevent their folding. The chaperone binding helps to keep the signal...
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Protein Modifications in the RER01:26

Protein Modifications in the RER

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Modification of secretory and transmembrane proteins entering the rough ER begins in the ER lumen. These modifications aid in protein folding and stabilize the acquired tertiary structure. Protein modifications in the rough ER co-occur at different stages of protein folding.
Broadly, these modifications can be categorized into four main categories — glycosylation, formation of disulfide bonds, assembly of protein subunits, and specific proteolytic cleavages like removal of signal...
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Regulation of the Unfolded Protein Response01:31

Regulation of the Unfolded Protein Response

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Inositol-requiring kinase one or IRE1 is the most conserved eukaryotic unfolded protein response (UPR) receptor. It is a type I transmembrane protein kinase receptor with a distinctive site-specific RNase activity. As the binding mechanics of the misfolded proteins with the N-terminal domain of IRE-1 are unclear, three binding models — direct, indirect, and allosteric -- are proposed for receptor activation. Nevertheless, it is known that once a misfolded protein associates with IRE1, it...
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Cotranslational Protein Translocation01:20

Cotranslational Protein Translocation

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Translocation of proteins across membranes is an ancient process that occurs even in bacteria and archaebacteria. In fact, the components of the translocation machinery are still conserved between prokaryotes and eukaryotes.
Sec61 channel partners for cotranslational translocation
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Detection of the pH-dependent Activity of Escherichia coli Chaperone HdeB In Vitro and In Vivo
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Chaperone function in Fe-S protein biogenesis: Three possible scenarios.

Jaroslaw Marszalek1, Elizabeth A Craig2, Marcin Pitek1

  • 1Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk, Poland.

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|April 4, 2024
PubMed
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The ISC machinery, essential for iron-sulfur cluster biogenesis, utilizes a unique chaperone system. This review explores the chaperone

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Defining Hsp33's Redox-regulated Chaperone Activity and Mapping Conformational Changes on Hsp33 Using Hydrogen-deuterium Exchange Mass Spectrometry
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In Situ Monitoring of Transiently Formed Molecular Chaperone Assemblies in Bacteria, Yeast, and Human Cells
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In Situ Monitoring of Transiently Formed Molecular Chaperone Assemblies in Bacteria, Yeast, and Human Cells
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Area of Science:

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Background:

  • Iron-sulfur (FeS) clusters are vital cofactors for numerous proteins.
  • FeS cluster biogenesis involves complex machinery, with the ISC system being unique due to its reliance on molecular chaperones.
  • The Hsc20/Hsp70 chaperone system interacts with IscU, a scaffold protein crucial for FeS cluster assembly and transfer.

Purpose of the Study:

  • To review the specific roles of the molecular chaperone system in the iron-sulfur cluster (ISC) machinery.
  • To elucidate the functions of the Hsc20/Hsp70 chaperones in FeS cluster biogenesis.
  • To explore potential mechanisms of chaperone involvement in cluster transfer and IscU regulation.

Main Methods:

  • Literature review of existing research on the ISC machinery and its associated chaperones.
  • Analysis of proposed models for chaperone function in FeS cluster biogenesis.
  • Synthesis of current knowledge regarding chaperone interactions with IscU and FeS cluster transfer.

Main Results:

  • The precise functions of the Hsc20/Hsp70 chaperone system within the ISC machinery remain incompletely understood.
  • Three potential, non-exclusive roles for the chaperones are discussed: involvement in cluster transfer, regulation of IscU levels, and facilitating assembly.
  • Chaperone involvement is critical for the efficient function of the ISC machinery.

Conclusions:

  • The Hsc20/Hsp70 chaperone system plays an essential, albeit not fully defined, role in iron-sulfur cluster biogenesis via the ISC machinery.
  • Further research is needed to precisely delineate the chaperone's contributions to cluster transfer and the regulation of the scaffold protein IscU.
  • Understanding these chaperone functions is key to comprehending FeS cluster homeostasis and its impact on cellular processes.