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Related Concept Videos

Molecular Chaperones and Protein Folding03:00

Molecular Chaperones and Protein Folding

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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.
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Bacterial Protein Maturation01:26

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Bacterial protein maturation is a tightly regulated process that ensures newly synthesized polypeptides achieve correct functional conformations. This maturation involves a series of modifications, folding events, and quality control steps, often assisted by specialized chaperone proteins.N-Terminal ModificationsThe maturation of bacterial polypeptides begins cotranslationally as the polypeptide exits the ribosome. The first amino acid, N-formylmethionine (fMet), is typically modified at the...
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Energy to Drive Translocation01:37

Energy to Drive Translocation

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Mitochondrial protein import is powered by two distinct energy sources: ATP hydrolysis and electrochemical potential across the inner membrane. Newly synthesized precursors are bound by cytosolic chaperones of the Hsp70 family, which guide them to the import receptors on the mitochondrial surface. Utilizing the energy of ATP hydrolysis, Hsp70 chaperones transfer these precursors to the TOM receptors on the mitochondrial outer membrane.
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Post-translational Translocation of Proteins to the RER01:27

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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
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Protein Complex Assembly02:41

Protein Complex Assembly

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Proteins can form homomeric complexes with another unit of the same protein or heteromeric complexes with different types.  Most protein complexes self-assemble spontaneously via ordered pathways, while some proteins need assembly factors that guide their proper assembly. Despite the crowded intracellular environment, proteins usually interact with their correct partners and form functional complexes.
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Translocation of Proteins into the Mitochondria01:19

Translocation of Proteins into the Mitochondria

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Mitochondrial precursors are translocated to the internal subcompartments via independent mechanisms involving distinct protein machineries called translocases.
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Specification of Hsp70 Function by Hsp40 Co-chaperones.

Douglas M Cyr1, Carlos H Ramos2

  • 1Department of Cell Biology and Physiology, School of Medicine University of North Carolina, Chapel Hill, NC, USA. dmcyr@med.unc.edu.

Sub-Cellular Biochemistry
|December 15, 2022
PubMed
Summary

Molecular chaperones, including Heat Shock Protein 70 (Hsp70) and its co-chaperones Heat Shock Protein 40 (Hsp40), maintain cellular proteostasis. This review details how Hsp40s direct Hsp70 clients toward protein folding or degradation pathways.

Keywords:
Hsp40Hsp70Molecular chaperoneProtein foldingProtein triage

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Area of Science:

  • Cellular biology
  • Molecular biology
  • Biochemistry

Background:

  • Cellular homeostasis relies on maintaining protein integrity and preventing proteotoxicity.
  • Molecular chaperones are crucial for cell survival, aiding in protein folding, refolding, and degradation of damaged proteins.
  • Heat Shock Protein 70 (Hsp70) plays a vital role in cellular protein metabolism by interacting with non-native proteins.

Approach:

  • This review focuses on the role of Heat Shock Protein 40 (Hsp40) family members as Hsp70 co-chaperones.
  • Hsp40s utilize their intrinsic chaperone activity to identify and bind misfolded proteins, selecting substrates for Hsp70.
  • The J-domain of Hsp40 stimulates Hsp70's ATPase activity, stabilizing their interaction with client proteins.

Key Points:

  • Hsp40s act as crucial regulators, determining the fate of Hsp70 client proteins.
  • Specialized sub-domains within different Hsp40s direct specific clients towards either protein folding or degradation.
  • This triage mechanism is essential for preventing proteotoxicity and maintaining cellular function under stress.

Conclusions:

  • Hsp40s are key mediators in the cellular response to proteotoxic stress.
  • Understanding Hsp40 mechanisms provides insight into protein quality control pathways.
  • Targeting Hsp40-Hsp70 interactions could offer therapeutic strategies for protein-misfolding diseases.