Major Histocompatibility Complex MHC

Question 1

MHC are

Answer 1

PM bound glycoproteins

Question 2

MHC fn

Answer 2

to present peptide ligands to T cells

Question 3

MHC I is found on

Answer 3

all nucleated cells (meaning not on RBC)

Question 4

MHC II are found on

Answer 4

only antigen presenting cells such as dendritic cells, macrophage and B cells

Question 5

MHC I how many peptides

Answer 5

composed of 2 polypeptides

Question 6

MHC I larger peptide

Answer 6

larger one called alpha chain; compose of 3 external domains (a1,a2,a3), a transmembrane region followed by a cytoplasmic region

Question 7

MHC smaller peptide

Answer 7

called beta2-microglobulin. noncovalently bound to the alpha chain

Question 8

Beta2-microglobuline and alpha3 domains similarities

Answer 8

in structure and sequence homology to the constant region of immunoglobulins, called immunoglobulin-like domain

Question 9

alpha1 and alpha2 form a

Answer 9

peptide binding cleft

Question 10

MHC II components

Answer 10

2 diff polypeptides, alpha and beta chain, non covalently associated.

Question 11

what are the alpha and beta chains of MHC II composed of

Answer 11

2 external domains, a transmembrane region and a cytoplasmic region. a2 and b2 domains are Ig-like domains.

Question 12

fn of MHC

Answer 12

present antigenic peptides to T cells

Question 13

MHC I presents antigenic peptides derived from

Answer 13

cytoplasmic proteins to CD8 T cells. these proteins could be viral or bacterial

Question 14

proteosome

Answer 14

enzyme complex that degrades endogenous proteins

Question 15

TAP

Answer 15

trasnmembrane protein that transpoorts resulting peptides into the RER

Question 16

what happens to MHC I once inside the RER

Answer 16

peptide can bind to MHC I. MHC I-peptide complex is then transported to cell’s PM

Question 17

fn of MHC II

Answer 17

to present exogenous peptides to CD4+ T cells. antigen presenting cells take up exogenous antigen by phogocytosis/endocytosis

Question 18

invariant chain (Ii) fn

Answer 18

in RER, protein that binds too peptide binding cleft of MHC II to prevent endogenous peptides from binding

Question 19

where is the MHC II-invariant chain transported to

Answer 19

phagosome/endosome, where invariant chain is degraded. exogenous peptide binds to cleft. MCH II-peptide complex transported to PM

Question 20

is binding of peptides to MHC specific

Answer 20

no