Ingham-7: MHC II

Question 1

What does dRIPs stand for?

Answer 1

defective ribosomal products

Question 2

How are dRIPs produced?

Answer 2

• improperly spliced mRNAs

- ribosomal frameshifts

Question 3

Where are amino acids ubiquitylated?

Answer 3

epsilon amino group of Lys

Question 4

Describe components of 26S proteosome

Answer 4

• 19S “lid”

- 20S core

Question 5

Function of 19S lid (x3)

Answer 5

• binds ubiquitin
• unfolds proteins that are not completely folded
• recycles ubiquitin

Question 6

Function of 20S core

Answer 6

contains proteasomes that chop up proteins

Question 7

What is special about 20S core in proteasome of pAPCs?

Answer 7

it has a special subunits to make the immunoproteasome

Question 8

What proteases are in the immunoproteasome?

Answer 8

LMP2, LMP7, LMP10

Question 9

What cytokines upregulate the expression of subunits of the immunoproteasome?

Answer 9

IFN-gamma and TNF-alpha

Question 10

Importance of PA28

Answer 10

allows increased peptide generation

Question 11

What does PA28 replace in immunoproteasome?

Answer 11

19S

Question 12

Function of TAP

Answer 12

• ATP-dependent transporter that transfers peptides into RER

Question 13

Where are the alpha and beta-2 microglobulin chains synthesized?

Answer 13

RER lumen

Question 14

Function of calnexin and ERPp57?

Answer 14

bind partially folded alpha chain (help fold it)

Question 15

Components of the peptide loading complex

Answer 15

• TAP transporter
• Calreticulin
• Tapasin
• ERp57

Question 16

Function of tapasin

Answer 16

links TAP to alpha chain and beta-2 microglobulin complex

Question 17

Function of ERp57 (more specific)

Answer 17

breaks and reforms disulfide bonds to help fold alpha chain

Question 18

Mutations in what genes cause bare lymphocyte symdrome type 1

Answer 18

TAP1 or TAP2 genes

Question 19

What does MIIC stand for?

Answer 19

MHC Class II-containing compartment

Question 20

Where are the alpha and beta chains for MHC II synthesized?

Answer 20

RER

Question 21

Function of the invariant chain (Ii)

x3

Answer 21

• prevents peptides from binding to MHC II in RER
• helps fold MHC II
• directs MHC II out of ER and towards low endosomal compartments

Question 22

Function of cathepsinf

Answer 22

• cleaves Ii in acidic vesicles

Question 23

Function of CLIP

Answer 23

prevents peptides from binding to peptide biding groove

Question 24

Significance of the MIIC late endosome

Answer 24

• MHC II/CLIP complex meets broken down peptides and binds them

Question 25

Function of HLA-DM

Answer 25

binds MHC II/CLIP complex and promotes release of CLIP and binding of internalized peptide

Question 26

What mutations cause bare lymphocyte syndrome type 2?

Answer 26

mutations in TFs that promote MHC II expression

Question 27

What is cross presentation?

Answer 27

exogenous Ags can get into the Class I pathway