10 - Antigen Processing and Presentation

Question 1

Which pathway are endogenous antigens processed by and which MHC molecule is it presented on?

Answer 1

cytosolic/enodgenous pathway | MHC class I

Question 2

Which pathway are exogenous antigens processed by and which MHC molecule is it presented on?

Answer 2

exogenous pathway | MHC class II

Question 3

MHC class I interact with peptides derived from?

Answer 3

cytosolic degradation of endogenously-synthesized proteins

Question 4

MHC class II interact with peptides derived from?

Answer 4

endocytic degradation of exogenous antigens

Question 5

What is the secretory pathway? What are the 3 places products in this pathway end up at?

Answer 5

intracellular pathway | take cytosolic proteins and package them into intracellular vesicles to either be: secreted, on the surface, or in lysosomes | endogenous antigen

Question 6

What is the endocytic pathway?

Answer 6

taking something up (endocytose) and target it into endosome and lysosome for degradation | exogenous antigen

Question 7

What are the 2 methods in which the amount of each type of protein inside a cell is regulated by?

Answer 7

protein degradation | synthesis of new proteins

Question 8

What are the 2 organelles in which proteins are degraded in?

Answer 8

lysosome | proteosome

Question 9

What are the protease complexes that generate the peptides that associate with MHC I?

Answer 9

proteosomes

Question 10

What is an immunoproteosome?

Answer 10

proteosome = more efficient at cutting up proteins to specific fragment length needed to bind to MHC I

Question 11

What is the function of proteosomes?

Answer 11

recognizes and degrades ubiquitin-tagged intracellular proteins

Question 12

Where are immunoproteasomes found and which cells can activate them?

Answer 12

all nucleated cells | by APCs

Question 13

What is the role of chaperones in the endogenous pathway? What is one key chaperone mentioned?

Answer 13

helps with protein folding in the ER | folds MHC I molecule and ensures peptide is bound to MHC I | calnexin

Question 14

What is the function of the TAP protein?

Answer 14

shuttles cytosolic peptides into the lumen of RER

Question 15

What are the 3 ways that extracellular antigens can get into intracellular vesicles?

Answer 15

actin-mediated phagocytosis | receptor-mediated endocytosis | autophagy

Question 16

Where are the internalized antigens that will associated with MHC II found?

Answer 16

endosome

Question 17

How do B-cells take extracellular antigens up into itself?

Answer 17

receptor-mediated endocytosis

Question 18

What allows for the dissociation of the peptide from the receptor?

Answer 18

drop in pH in the late endosome

Question 19

What is the role of the invariant chain (li)?

Answer 19

associates with MHC II in ER lumen = blocks MHC II peptide binding site to ensure that MHC II won’t get loaded with peptides for MHC I

Question 20

What is CLIP?

Answer 20

protein blocking peptide binding groove after invariant chain is degraded

Question 21

What is HLA-DM?

Answer 21

exchanges CLIP out for the processed exogenous peptide to bind on MHC II

Question 22

How is the invariant chain degraded?

Answer 22

via proteolytic activity

Question 23

What is Cross-Presentation of exogenous antigens

Answer 23

a way for MHC I to present an exogenous peptide | exogenous antigens are redirected to the endogenous presentation pathway

Question 24

What is the purpose of the Cross-Presentation of exogenous antigen? Why does it need to be presented on MHC I and not on MHC II?

Answer 24

to activate CD8 T-cells | normal cells cannot activate CD8 T-cells, only APCs

Question 25

Which cells can activate CD8 T-cells?

Answer 25

APCs

Question 26

Which cell carries put cross-presentation?

Answer 26

ONLY dendritic cells