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6.2 Antigen Processing β Test 1
Q1. Endogenous (cytosolic) antigens are degraded for MHC class I presentation by the:β Proteasome
Q2. Peptides destined for MHC class I are transported into the endoplasmic reticulum by:β TAP (transporter associated with antigen processing)
Q3. Exogenous antigens for MHC class II presentation are degraded in the:β Endosomal/lysosomal compartment
Q4. Before a class II molecule can bind antigenic peptide, its groove is occupied by:β The invariant chain (and its CLIP fragment)
Q5. HLA-DM functions in the class II pathway to:β Catalyse exchange of CLIP for antigenic peptide
Q6. Cross-presentation refers to the ability of some dendritic cells to:β Present exogenous antigens on MHC class I to CD8 T cells
Q7. The proteasome variant induced by IFN-Ξ³ to optimise class I peptide generation is the:β Immunoproteasome
Q8. A virus that blocks TAP would impair:β MHC class I presentation of viral peptides
Q9. The peptide-loading complex in the ER, which aids class I assembly, includes:β Tapasin, calreticulin and ERp57 with TAP
Q10. Why do almost all nucleated cells need the class I processing pathway?β So cytotoxic T cells can detect intracellular infection or transformation in any cell
Q11. Professional antigen-presenting cells are distinguished by their ability to:β Express MHC class II and provide co-stimulation
Q12. The invariant chain (Ii) directs newly synthesised class II molecules to:β The endosomal/lysosomal compartment for peptide loading
Q13. Loss of MHC class I on a virus-infected or tumour cell makes it a target for:β NK cells (recognising 'missing self')
Q14. MHC class I typically presents peptides of approximately:β 8β10 amino acids
Q15. MHC class II typically presents peptides of approximately:β 13β25 amino acids (and longer, with open ends)
Q16. Ubiquitination of a cytosolic protein primarily marks it for:β Degradation by the proteasome
Q17. The two distinct processing pathways ensure that:β Intracellular antigens go to CD8 (class I) and extracellular antigens to CD4 (class II)
Q18. A defect in the class II pathway (e.g. bare lymphocyte syndrome) leads to:β Impaired CD4 helper responses due to absent class II expression
Q19. Peptides generated by the proteasome are further trimmed before/after ER entry by:β Aminopeptidases (e.g. ERAP)
Q20. MHC class I and class II molecules are associated, respectively, with which antigen-processing pathways?β Cytosolic (endogenous) and endocytic (exogenous) pathways
Q21. The proteasome generates peptides in which antigen-processing pathway?β The cytosolic (class I) pathway
Q22. TAP (transporter associated with antigen processing) operates in which pathway?β The cytosolic (class I) pathway
Q23. The invariant chain blocks the antigen-binding groove of newly synthesised MHC II in which pathway?β The endocytic (class II) pathway
Q24. The invariant chain blocks the MHC II groove in order to:β Prevent endogenous (cytosolic) peptides binding MHC II prematurely
Q25. Cytosolic (e.g. viral) protein-antigen fragments are presented on:β MHC class I molecules
Q26. Match each molecule with its role in antigen processing and select the correct option.β A-ii, B-i, C-iv, D-iii