L11_T-Cell Receptor

Question 1

What does MHC stand for?

Answer 1

Major Histocompatability Complex

Question 2

How do cells monitor what is going on inside of them and communicate this to the outside world?

Answer 2

peptide presenting MHC molecules

Question 3

Describe the difference in how B-cells and T-cells recognize antigen

Answer 3

B-cells recognize the native form of the foreign antigen in its 3D structure. They can recognize protein, carbohydrate or lipids. T cells recognize short peptide sequences presented by MHC that can originate form anywhere in the foreign protein. T- cells only recognize protein

Question 4

describe the biochemical characterization of TCRs

Answer 4

Disulfide linked heterodimer, transmembrane protein, constant and variable regions in both chains, Both chains are glycoproteins

Question 5

Is there more diversity in TCR or BCRs

Answer 5

TCR

Question 6

What MHC class generally presents the following pathogens on the cell surface? Cytosolic, Intravesicular, Endocytosed extracellular

Answer 6

MHC1, MHC2, MHC2

Question 7

What has stronger affinity for its target, TCR or Antibody?

Answer 7

Antibody

Question 8

How do TCRs help increase sensitivity for their targets?

Answer 8

CD8 and CD4 recognize specific MHC

Question 9

What do CD4 and CD8 recognize and are they dimers or monomers?

Answer 9

CD4 recognized MHCII and is a monomer. CD8 recognizes MHCI and is a heterodimer.

Question 10

What region of the MHC receptors does CD4 and CD8 recognize?

Answer 10

The constant region of MHC molecules.

Question 11

Describe the difference of how gamma delta recognized antigen compared to alpha beta

Answer 11

gamma delta recognize much more similar to a BCR by recognizing the 3D antigen even if it is not attached to MHC but is still acting as a TCR.

Question 12

How do superantigens work? what is one species that is well known for producing superantigens.

Answer 12

Staph Aureus enterotoxin. Superantigens glue together TCR and MHC molecules in a non specific manner which causes a massive cytokine storm which leads to shock. Some people are more susceptible than others. generally bind to Vbeta domain of TCR. Superantigens can cause 1 in 4 T-cells to respond to MHC compared to 1 in 1000-10000 in a normal immune response

Question 13

Identify MHCI and MHCII as monomer or dimer

Answer 13

MHCI is a 3 subunit monomer that interacts with Beta2 microglobulin. MHCII is a heterodimer (alpha and beta)

Question 14

Identify the HLA genes that make up Class 1 and 2 MHC molecules

Answer 14

MHCI - HLA-A, HLA-B, HLA-C

MHCII - HLA-D alpha and beta chain (Subclasses DP, DQ, DR)

Question 15

What is the purpose of the DO and DM genes of MHCII

Answer 15

They help with loading the peptide onto the other (DR, DP, DQ)

Question 16

Where is there more diversity, in the individual alpha beta genes of the MHCII or in the A, B, or C genes of MHCI

Answer 16

A,B, and C of MHCI because thats all you get. There is now diversity from combination of two chains like in MHCII

Question 17

Describe how the TCR sees the peptide sequence and MHC structure differently

Answer 17

It sees the 3D structure of MHC and the linear AA sequence of the protein fragment.

Question 18

What cells express MHCI

Answer 18

All nucleated cells

Question 19

What cells express MHCII

Answer 19

subset of hematopoietic cells and thymic stromal cells: B-cells, Macrophages, Other APC (langerhans and dendritic) and epithelial cells of the thymus

Question 20

What are the 3 requirements for presentation of MHCI

Answer 20

1. Beta2 Microglobulin
2. Properly folded monomer
3. Peptide in binding groove

Question 21

What subunits of MHCI create the binding groove?

Answer 21

alpha 1 and alpha 2

Question 22

What subunits of MHCII create the binding groove in MHCII

Answer 22

alpha 1 and beta 1

Question 23

What is the major difference between the binding groove in MHCI and MHCII?

Answer 23

MHC1 binding groove is closed off at either end which restricts the length of the peptide to smaller fragments (8-10AA). The MHCII binding groove is open and can house large and more variable peptide chains (at least 12-13AA)

Question 24

What are the vesicles called that carry MHCII molecules and fuse with endolysozomes that contain antigen

Answer 24

M2C vesicles.

Question 25

How do MHCI molecules come into contact with antigen peptides?

Answer 25

Cytosolic proteins are broken down by proteosome. ATP-dependent TAP moves these peptide into the ER where the MHCI molecule is help inactivated by chaperones. THe peptide binds, the chaperones release, and the MHCI is moved to the cell membrane through default pathway.

Question 26

does affinity maturation occur with T-Cells?

Answer 26

NO

Question 27

What is the primary function of a T-cell?

Answer 27

To monitor the intracellular environment of the host cell.

Question 28

State whether MHC I and II are monomers or dimers

Answer 28

MHC I is a monomer, MHC II is a dimer

Question 29

To what portions of the MHC and TCR do super antigens bind?

Answer 29

The variable regions. Specifically the Vbeta of the TCR