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Questions and Answers
What is usually synonymous with the acquisition of antigen during a viral infection?
What is usually synonymous with the acquisition of antigen during a viral infection?
the infected state
What do viruses rely on to generate new viral proteins?
What do viruses rely on to generate new viral proteins?
What process involves polyubiquitinylation to target a protein for destruction?
What process involves polyubiquitinylation to target a protein for destruction?
Targeting antigen for destruction
Protein synthesis is a perfect process with no errors involved.
Protein synthesis is a perfect process with no errors involved.
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Error-containing proteins must be rapidly removed to prevent clogging up the ______.
Error-containing proteins must be rapidly removed to prevent clogging up the ______.
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What is the significance of properly folded proteins in the context of the class I MHC pathway?
What is the significance of properly folded proteins in the context of the class I MHC pathway?
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Study Notes
Class I MHC Pathway
- The Class I MHC pathway presents cytosolic antigens
- Viral infection commonly triggers Class I MHC pathway activation.
- Viruses rely on the host cell's biosynthetic machinery, creating new viral proteins.
- Protein synthesis can be error-prone, leading to premature termination of nascent polypeptide chains, misincorporation of amino acids, and improper folding.
- Errors in protein synthesis can affect both host proteins and viral proteins.
- Errors in protein synthesis necessitate a rapid removal mechanism to prevent disruption of the cellular machinery.
Acquisition of Antigen
- Error-containing proteins represent a significant source of peptides destined for presentation by Class I MHC molecules.
- The Class I MHC pathway primarily processes peptides derived from proteins synthesized by the host cell.
Targeting Antigen for Destruction
- Polyubiquitinylation plays a crucial role in the process of targeting proteins for destruction.
- Ubiquitin is a small protein that acts as a tag when attached to other proteins in the "polyubiquitinylation" process.
- The process of polyubiquitinylation is tightly regulated.
Proteasome & Peptide Processing
- The proteasome, a protein complex, degrades polyubiquitinated proteins.
- The proteasome breaks down targeted proteins into smaller peptides.
- These peptides are then passed into the endoplasmic reticulum (ER).
Peptide Transportation
- The transporter associated with antigen processing (TAP) transports peptides from the cytosol into the ER.
- TAP1 and TAP 2 are a pair of proteins that make up TAP.
Peptide Loading complex
- In the ER, peptides bind to the peptide-loading complex, a multi-protein complex.
- This complex includes:
- Class I MHC molecules
- Tapasin
- Calreticulin
- ERp57
- Calnexin
- This complex helps in loading peptides onto Class I MHC molecules.
Plasma membrane presentation
- Loaded peptide-MHC complex is transported to the cell surface.
- The peptide-MHC complex is presented to the immune system for recognition by T cells.
- Class I MHC pathways present antigens that are derived from proteins synthesized by the cell itself (endogenous antigens).
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Description
Test your knowledge on the Class I MHC pathway, which is vital for presenting cytosolic antigens. Learn how viral infections trigger this pathway and the implications of errors in protein synthesis. This quiz covers the mechanisms of antigen acquisition and targeting for destruction.
