Question

4. Contrast the role of the proteosome vs. lysosome in the generation of antigenic peptide for MHC display. Be sure to address 1) the pathways in which they act, 2) the nature of the peptides produced, 3) how/where these peptides bind to the MHC, 4) how the peptides are matched to the binding sites of their respective MHC complexes.

Answer 1

PROTEOSOME

1. The pathway in which they act is ubiquitin-proteasome pathway.

2.The nature of peptides produced are immunoproteosomes.

3.The peptides binds to MHC at endoplasmic reticulum which are transported from cystol.

4.The peptides are matched to the binding sites of there respective MHC complex by anchor residue.These are located at the C-terminal of peptide which are enriched with hydrophobic residue.These peptide residue  then matches with the specific MHC Class 1 molecules's halotype and should form a stable peptide bond.

LYSOSOME

1. The pathway in which they act is  MHC class II processing and presentation pathway.

2.The nature of peptides produced are CLIP or Class II-associated invariant chain peptide.

3.The peptides binds to MHC at endosome compartment.

4. The peptides are matched to the binding sites of there respective MHC complex by recognizing a peptide with 13 to 17 amino acid which is shortened from C-terminal.