Protein Degradation - Proteasome Overview
42 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Which statement correctly describes the role of chaperon BiP?

  • BiP promotes the dimerization of IRE1.
  • BiP binds only to unfolded proteins without interacting with IRE1.
  • BiP assists in the proper folding of proteins. (correct)
  • BiP is a prokaryotic protein that degrades proteins.

What is the main function of the proteasome in protein degradation?

  • To catalyze the synthesis of new proteins.
  • To solely assist in protein folding.
  • To degrade ubiquitinated proteins into peptides. (correct)
  • To recycle proteins back into their original shape.

Which of the following is NOT a consideration in the degradation process?

  • Maintenance of dynamic homeostasis of structural proteins.
  • Spatial and temporal control of protein degradation.
  • Necessity of compartmentalization in prokaryotes.
  • Universal presence of proteasomes in all living organisms. (correct)

What role does PERK play in the response to unfolded proteins?

<p>It activates a specific kinase related to protein synthesis. (B)</p> Signup and view all the answers

How is ubiquitination involved in the process of ERAD?

<p>It signals proteins for degradation by the proteasome. (A)</p> Signup and view all the answers

What is the primary role of the proteasome in cellular function?

<p>Degrade misfolded or damaged proteins (D)</p> Signup and view all the answers

What does ERAD stand for in the context of protein management?

<p>Endoplasmic Reticulum Associated Degradation (D)</p> Signup and view all the answers

What can trigger the Unfolded Protein Response (UPR)?

<p>Overproduction of unfolded or misfolded proteins (D)</p> Signup and view all the answers

Which class of disease is characterized by loss of function of a protein through mutation?

<p>Class I (C)</p> Signup and view all the answers

How does the presence of mutated proteins impact the endoplasmic reticulum?

<p>Leads to overcharge and potential ER derangement (B)</p> Signup and view all the answers

What is the primary role of the proteasome in protein degradation?

<p>To degrade misfolded or damaged proteins (D)</p> Signup and view all the answers

What is one function of chaperones in the context of the proteasome?

<p>Assist in the folding of newly synthesized proteins (D)</p> Signup and view all the answers

What does UPR stand for and what is its role in the cell?

<p>Unfolded Protein Response, a mechanism to manage protein folding (A)</p> Signup and view all the answers

What process is primarily responsible for directing proteins to the proteasome for degradation?

<p>Ubiquitination (D)</p> Signup and view all the answers

Which disease is associated with dysfunctional CFTR protein linked to proteasome activity?

<p>Cystic fibrosis (C)</p> Signup and view all the answers

What can be a consequence of an overloaded endoplasmic reticulum?

<p>Increased transcription of chaperone proteins (D)</p> Signup and view all the answers

What is one potential consequence of improperly folded proteins aggregating in eukaryotic cells?

<p>Formation of toxic aggregates (D)</p> Signup and view all the answers

Which of the following statements about the proteasome is accurate?

<p>It is an essential component for degrading misfolded proteins. (D)</p> Signup and view all the answers

How does the endoplasmic reticulum (ER) assist in protein degradation?

<p>By managing the folding and degradation of proteins through ERAD. (A)</p> Signup and view all the answers

What role do chaperons play in protein management within the cell?

<p>They inhibit protein aggregation. (C)</p> Signup and view all the answers

What can be a consequence of glycation on proteins?

<p>It inhibits the activity of certain proteins. (C)</p> Signup and view all the answers

What is the primary function of reverse chaperons in the degradation process?

<p>Promoting protein solubility and unfolding (D)</p> Signup and view all the answers

Which factor is critical for the assembly and function of the proteasome?

<p>Ubiquitin (D)</p> Signup and view all the answers

What is one risk associated with the degradation process within the cell?

<p>Inadequate regulation of protein degradation (D)</p> Signup and view all the answers

How does PERK contribute to the response to unfolded proteins?

<p>By enhancing chaperon expression (C)</p> Signup and view all the answers

Which of the following statements accurately describes the role of the endoplasmic reticulum (ER) in protein degradation?

<p>ER mediates the passage of proteins to the proteasome (B)</p> Signup and view all the answers

What happens when the load on the endoplasmic reticulum (ER) exceeds its capacity?

<p>Unfolded proteins are dispatched to the proteasome (B)</p> Signup and view all the answers

Which process is crucial for tagging proteins to be degraded in the proteasome?

<p>Ubiquitination (B)</p> Signup and view all the answers

What is one role of chaperones in the context of the proteasome?

<p>To facilitate the correct folding of proteins (B)</p> Signup and view all the answers

What can be a direct consequence of a defect in the Unfolded Protein Response (UPR)?

<p>Increased apoptosis rates (A)</p> Signup and view all the answers

Which type of cellular stress can trigger the Unfolded Protein Response (UPR)?

<p>Accumulation of misfolded proteins (C)</p> Signup and view all the answers

What is the primary consequence of ERAD (Endoplasmic Reticulum Associated Destruction)?

<p>Destruction of faulty proteins to maintain cell quality (B)</p> Signup and view all the answers

How does the proteasome assist in maintaining cellular homeostasis?

<p>By degrading misfolded and damaged proteins (D)</p> Signup and view all the answers

What role does the UPR play in the response to endoplasmic reticulum stress?

<p>Induces genes related to protein folding and degradation (C)</p> Signup and view all the answers

Which of the following correctly describes a function of chaperons during protein degradation?

<p>They assist in protein folding and prevent aggregation. (B)</p> Signup and view all the answers

What is the role of the proteasome in the context of cellular protein management?

<p>To degrade misfolded or damaged proteins. (C)</p> Signup and view all the answers

In the process of ER-associated degradation (ERAD), what is the initial step taken for misfolded proteins?

<p>They are ubiquitinated to mark them for degradation. (C)</p> Signup and view all the answers

What occurs during the unfolded protein response (UPR)?

<p>The cell mounts a response to reduce protein aggregation. (D)</p> Signup and view all the answers

Which statement about proteasome structure is accurate?

<p>It is made up of multiple subunits that form a hollow cylindrical structure. (C)</p> Signup and view all the answers

What is a common consequence of improperly folded proteins in eukaryotic cells?

<p>They can lead to toxic aggregates causing cell dysfunction. (D)</p> Signup and view all the answers

Which condition can lead to the activation of the unfolded protein response (UPR)?

<p>Elevated levels of unfolded or misfolded proteins. (A)</p> Signup and view all the answers

How does glycation affect proteins, according to common findings?

<p>It is a non-enzymatic reaction that inhibits their activity. (C)</p> Signup and view all the answers

Flashcards

BiP (Binding Immunoglobulin Protein)

A protein chaperone that binds to unfolded proteins or to the IRE1 protein in the ER, playing a key role in the unfolded protein response (UPR).

Unfolded Protein Response (UPR)

A system in the ER that helps maintain protein homeostasis by detecting and responding to misfolded or unfolded proteins.

ERAD (ER-associated Degradation)

A protein that is responsible for degrading misfolded or damaged proteins in the ER. It is also involved in the process of ubiquitination, marking proteins for degradation by the proteasome.

Proteasome

A large protein complex that degrades proteins tagged with ubiquitin chains. It plays a crucial role in cellular processes such as cell cycle control, immune responses, and signal transduction.

Signup and view all the flashcards

Ubiquitination

A process by which multiple ubiquitin proteins are attached to a target protein, marking it for degradation by the proteasome.

Signup and view all the flashcards

Protein Degradation

The process of breaking down proteins into smaller peptides or amino acids.

Signup and view all the flashcards

ER-associated Degradation (ERAD)

A process by which misfolded proteins are recognized and transported from the ER to the cytosol for degradation by the proteasome.

Signup and view all the flashcards

Intracellular Proteolysis

The breakdown of proteins within a cell. It can occur in various compartments like the lysosome or the proteasome.

Signup and view all the flashcards

Protein Destruction

A cellular process that ensures the removal of misfolded proteins, preventing their accumulation and potential harmful effects.

Signup and view all the flashcards

Chaperons

A group of proteins that assist in the proper folding of other proteins.

Signup and view all the flashcards

What is the UPR?

The unfolded protein response (UPR) is a cellular stress response that is activated when misfolded proteins accumulate in the endoplasmic reticulum (ER). It aims to restore ER homeostasis by reducing protein synthesis, increasing chaperone expression, and promoting degradation of misfolded proteins.

Signup and view all the flashcards

What is ERAD?

ER-associated degradation (ERAD) is a quality control pathway that removes misfolded proteins from the ER. This process involves targeting the misfolded protein with ubiquitin, which signals for its transport to the proteasome for degradation.

Signup and view all the flashcards

What is the proteasome?

The proteasome is a large protein complex that breaks down proteins into smaller peptides. This process is crucial for regulating protein levels, removing damaged proteins, and controlling cellular processes.

Signup and view all the flashcards

What is ubiquitination?

Ubiquitination is a process where a small protein called ubiquitin is attached to a target protein. This tagging signals for the protein to be targeted for degradation by the proteasome.

Signup and view all the flashcards

What triggers ER stress?

ER stress can be triggered by various factors such as mutations in proteins, increased protein synthesis, and metabolic stress. It leads to an accumulation of unfolded proteins in the ER, ultimately impacting the entire cell.

Signup and view all the flashcards

How does the UPR respond to ER stress?

During ER stress, the UPR aims to reduce protein synthesis, increase chaperone expression, and promotes degradation of misfolded proteins. This process helps restore ER homeostasis and prevents cell damage.

Signup and view all the flashcards

What is the importance of ERAD?

ERAD plays a crucial role in maintaining cell function by removing misfolded proteins that can disrupt normal cellular processes. It helps prevent the accumulation of potentially harmful proteins in the cell.

Signup and view all the flashcards

What are the consequences of defects in UPR/ERAD?

Defects in the UPR or ERAD pathways are implicated in various diseases, including diabetes, hemophilia, and cystic fibrosis. These conditions arise from the impaired protein folding and degradation processes.

Signup and view all the flashcards

Proteasome Function

The ability of the proteasome to degrade ubiquitinated proteins, making it a key player in the process of protein destruction.

Signup and view all the flashcards

Importance of UPR/ERAD

The importance of the UPR and ERAD pathways is to prevent the accumulation of misfolded proteins in the ER, which can disrupt normal cellular processes and ultimately lead to cell death.

Signup and view all the flashcards

Consequences of defects in UPR/ERAD

Defects in the UPR or ERAD pathways can lead to various diseases, including diabetes, hemophilia and cystic fibrosis. These conditions arise from the impaired protein folding and degradation processes.

Signup and view all the flashcards

ER Capacity and Charge

The capacity of the ER to fold proteins correctly is linked to the amount of unfolded proteins that need to be processed.

Signup and view all the flashcards

Stress on the ER

This occurs when the demand for protein folding exceeds the capacity of the ER, resulting in a build-up of unfolded proteins. This triggers the UPR to restore balance.

Signup and view all the flashcards

Glycosylation

The process of attaching sugars to proteins through enzymatic reactions. It affects protein stability and function.

Signup and view all the flashcards

Glycation

A non-enzymatic reaction where sugars attach to proteins, primarily harming proteins and causing damage.

Signup and view all the flashcards

Study Notes

Protein Degradation - Proteasome

  • Protein degradation is essential for cellular function.
  • The unfolded protein response (UPR) is a cellular response to an increase in unfolded proteins in the endoplasmic reticulum.
  • ER-associated degradation (ERAD) is a pathway that targets misfolded proteins in the ER for degradation by the proteasome.
  • Ubiquitination is a process that marks proteins for degradation by the proteasome.
  • Proteasomes are large protein complexes that degrade target proteins.
  • Proteasome assembly and structure are critical functions.
  • The proteasome and chaperones work together in folding and destruction.
  • Eukaryotes may have up to 30% misfolded proteins at a time.
  • Toxic protein aggregates can be dominant negatives.
  • Misfolding can occur due to mutations, or post-synthetic damage (e.g., oxidation, glycation, deamidation).
  • There are ~50 diseases linked to UPS/ERAD which can also result in apoptosis.

Proteasome Overview

  • Proteasomes are involved in a range of cellular processes, far beyond the degradation of misfolded proteins.
  • Regulation of protein degradation provides homeostasis.
  • Protein control systems ensure accuracy and function are vital.
  • Protection of other cellular components is crucial, especially in bacteria that lack compartments.
  • Efficient machinery (auto-assembly, auto-organization) is needed.
  • Proteins destined for degradation in the ER require specific mechanisms to exit the ER, including the UPR and ERAD pathways.
  • The pathways are crucial for maintaining cellular health and function, influencing cellular processes such as immune response and antigen presentation.
  • Different types of ubiquitination (mono, multi- and poly-ubiquitination) can occur.

Ubiquitination

  • Ubiquitination is a crucial step in protein degradation.
  • Ubiquitination involves the attachment of a small protein called ubiquitin to a target protein. This can take different forms(mono, multi, poly).
  • Ubiquitination can be mono-, multi-, or poly-ubiquitination, with different outcomes.
  • Proteasomes recognize poly-ubiquitinated proteins for degradation.

Protein Degradation - Proteasome, Further considerations

  • Ubiquitination is essential for protein degradation.
  • The proteasome complex plays an important role in protein turnover within cells.
  • Spacial and temporal control is important during protein degradation, with compartments protecting cells from damage.
  • Compartmentalization protects cells from unwanted proteolysis damaging the cell.
  • Chaperones are needed for unfolding and to assist cells in protein folding.
  • The ER is not a degradation compartment but assists in the protein degradation process by chaperones and assistance mechanisms before a target protein can be degraded.

ERAD

  • ERAD is involved in degrading misfolded proteins in the endoplasmic reticulum (ER).
  • The process is tightly linked to folding and quality control.
  • ERAD plays a role in numerous cellular processes and requires different steps (induction/attenuation, retrotransport, degradation).
  • ERAD is an important quality control mechanism, ensuring proper function of proteins involved in various cellular processes.

Proteasomes: Steps in degradation

  • Binding
  • Unfolding
  • Translocation and hydrolysis
  • Release

Proteasome: Structure and Components

  • PA700, PA28, and other components are related to this.
  • Proteasome inhibitors can be a topic of therapeutic interest.

Proteasome: Other Aspects

  • Ubiquitin-like modifications (UBLs) are involved in protein regulation, transport, and degradation.
  • SUMO and NEDD8 are examples of UBLs with different roles and functions.
  • The different forms of ubiquitination allow different types of regulatory functions.
  • The structure of the proteasome is critical for its function, particularly the proteolytic chambers.
  • Proteasome chambers and their function are important to study, involving high-resolution EM, interactions with other proteins, cross-linking, X-ray, and NMR analysis.
  • Proteins can be acetylated for modification or as a signal for their degradation. Note that acetylation can impact protein folding, localization, and potentially degradation.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

Related Documents

Protein Degradation - Proteasome PDF

Description

Explore the essential role of proteasomes in protein degradation and cellular function. This quiz delves into concepts such as ubiquitination, the unfolded protein response, and ER-associated degradation pathways. Understand how misfolded proteins are targeted for degradation and the significant impact on cellular processes.

More Like This

Peptide Binding to Class I MHC Molecules
7 questions

Peptide Binding to Class I MHC Molecules

StupendousNovaculite avatar
StupendousNovaculite
Retta - L12
40 questions

Retta - L12

DeadCheapSage avatar
DeadCheapSage
Muscle Protein Degradation Quiz
7 questions

Muscle Protein Degradation Quiz

EffectiveMesa avatar
EffectiveMesa
Use Quizgecko on...
Browser
Open
Browser
Browser