MI 02b: Ab and TCRs

Question 1

Antibody, aka an (X) molecule/monomer, has (Y) structure.

Answer 1

X = Ig
Y = hetero-tetramer

Question 2

Ab has (X) heavy and (Y) light chains that are (non-covalently/covalently) joined by (Z) bonds.

Answer 2

X = Y = 2
Covalently;
Z = disulfide

Question 3

At the (carboxyl/amino) terminal end of (heavy/light) chains is the “variable” region of Ab.

Answer 3

Amino;

Both heavy and light chains

Question 4

At the (carboxyl/amino) terminal end of (heavy/light) chains is the “constant” region of Ab.

Answer 4

Caroxyl;

Both heavy and light chains

Question 5

Within (X) region of Ab, there are (2/3/4/5) stretches of (Y) that exhibit even greater degrees of variability between Ab molecules. What are these regions called?

Answer 5

X = variable
3;
Y = AA

Hypervariable regions or complementarity-determining regions (CDR1, CDR2, CDR3)

Question 6

Which region(s) on Ab are in contact/complementary to the antigen?

Answer 6

Hyper-variable regions (CDR1, 2, and 3)

Question 7

The (X) of the (H/L) chain of Ab determines the isotype.

Answer 7

X = AA sequence of constant region

H chain

Question 8

In humans, there are (X) number of Ab isotypes that are placed into (Y) number of classes. List the classes. Star those with subclasses.

Answer 8

X = 9
Y = 5

IgM, IgA, IgD, IgG, IgE

Question 9

All cell surface Ig classes are (mono/di/tri/tetra)-mers and anchored to the membrane through (C/N) terminus of (H/L) chain.

Answer 9

monomers;
C;
H

Question 10

In soluble form, which Ig classes are monomers?

Answer 10

IgD, IgG, IgE

Question 11

In soluble form, which Ig classes are dimers?

Answer 11

IgA

Question 12

In soluble form, which Ig classes are tetramers?

Answer 12

None

Question 13

In soluble form, which Ig classes are pentamers?

Answer 13

IgM

Question 14

In soluble form, the Ig classes that aren’t monomers are held together by:

Answer 14

J chain

Question 15

In soluble Ab, the (Fab/Fc) region is responsible for mediating effector functions, aka recruitment of (X), when the (Fab/Fc) region is (bound/unbound) to (Y).

Answer 15

Fc;
X = innate immune forces
Fab;
Bound
X = complementary antigen

Question 16

The TCR has (X) structure, composed of which chain(s)?

Answer 16

X = heterodimer

One alpha and one beta chains

Question 17

In TCR structure, (alpha/beta) chain consists of (N/C) variable region.

Answer 17

Both; N-terminal

Question 18

In TCR structure, (alpha/beta) chain consists of (N/C) constant region.

Answer 18

Both; C-terminal

Question 19

In TCR structure, (constant/variable) region traverses the (X) cell membrane.

Answer 19

Constant (C-terminal);

X = T cell

Question 20

T/F: CDR1, 2, and 3 hypervariable regions are exclusively found on Ab.

Answer 20

False

Question 21

Variable region of TCR contains which (if any) hypervariable regions?

Answer 21

CDR1, 2, and 3 (like Ab)

Question 22

T/F: A minority of TCRs are made up of gamma and delta chains.

Answer 22

True (5-10%)

Question 23

What’s an epitope?

Answer 23

Part of antigen that contacts the antigen receptor

Question 24

T/F: BCRs and TCRs recognize different types and forms of antigens.

Answer 24

True

Question 25

In soluble form, TCR forms (mono/di/tri)mer?

Answer 25

NEVER secreted in soluble form! Only on cell surface

Question 26

(BCR/TCR)s can recognize any chemical structure in its native form.

Answer 26

BCRs

Question 27

(BCR/TCR)s are high-maintenance. They only interact with (X)-derived (Y) that are presented in context of (Z).

Answer 27

TCRs; X = antigen Y = peptides Z = self-MHC molecules

Question 28

In general, TCRs CDR1 region interacts with:

Answer 28

MHC molecule

Question 29

In general, TCRs CDR2 region interacts with:

Answer 29

MHC molecule

Question 30

In general, TCRs CDR3 region interacts with:

Answer 30

Peptide

Question 31

T/F: MHC class I and II molecules are expressed on the same types of cells.

Answer 31

False

Question 32

MHC Class I molecules are expressed on (X) cells.

Answer 32

X = all nucleated

Question 33

MHC Class II molecules are expressed on (X) cells.

Answer 33

X = Antigen-presenting | and thymic epithelial cells

Question 34

MHC Class I molecule has (X) chains with (Y) number of domains. It's (covalently/non-covalently) associated with (Z).

Answer 34

X = one alpha Y = 3 Non-covalently Z = beta-2-microglobulin (beta-2m) protein

Question 35

MHC Class II molecule has (X) chains with (Y) number of domains. Its (covalently/non-covalently) associations form which structure?

Answer 35

X = one alpha and one beta Y = 2 domains on each chain Non-covalently; Heterodimer

Question 36

MHC class (I/II) contain peptide-binding cleft.

Answer 36

Both

Question 37

MHC Class I has peptide-binding cleft formed by (X) domain of (Y) chain.

Answer 37

``` X = first two Y = alpha ```

Question 38

MHC Class II has peptide-binding cleft formed by (X) domain of (Y) chain.

Answer 38

``` X = first Y = both alpha and beta chains ```

Question 39

The human MHC is also referred to as:

Answer 39

HLA (human leukocyte antigen)

Question 40

How many loci encode distinct human MHC class I proteins? List them. What does each locus encode?

Answer 40

3 loci HLA-A, HLA-B, HLA-C Each locus encodes one alpha chain

Question 41

How many loci encode distinct human MHC class II proteins? List them. What does each locus encode?

Answer 41

3 loci HLA-DP, HLA-DQ, HLA-DR Each locus encodes a distinct alpha and beta chain

Question 42

We inherit (X) sets of MHC alleles from each parent.

Answer 42

X = one

Question 43

T/F: The MHC loci are the most highly polymorphic loci in any mammalian genome.

Answer 43

True

Question 44

The majority of polymorphic AA in MHC molecules are localized in which part of molecule?

Answer 44

Peptide-binding cleft

Question 45

Each specific MHC molecule can bind peptides of (one/many) sequence(s) and (one/multiple) peptides at a time.

Answer 45

Many; | one

Question 46

What can you say about all peptides that can bind to one specific MHC molecule? Be specific.

Answer 46

They share structural features (similar AA residues at critical positions)

Question 47

What's the formal name of AA residues in critical positions that allow peptide to fit into binding pockets of MHC cleft.

Answer 47

Anchor residues

Question 48

AA residues on peptide that face away from MHC molecule interact with (X) and are thus called (Y).

Answer 48

``` X = TCR Y = TCR contact residues ```

Question 49

One individual will inherit (X) different MHC class I alleles from each parent.

Answer 49

X = 3

Question 50

One individual will inherit (X) different MHC class II alleles from each parent.

Answer 50

X = 3

Question 51

What determines which MHC Class I or II allele (from mom or dad) will be expressed on a given cell?

Answer 51

All alleles are expressed co-dominantly!

Question 52

Every individual is capable of producing (X) different MHC Class I proteins and (Y) different MHC Class II proteins.

Answer 52

``` X = 6; Y = 12 ```

Question 53

The disparity in (X) between individuals is the greatest contributor to rejection in organ/tissue transplantation.

Answer 53

X = MHC sequences

Question 54

MHC Class I molecules present (X) to which specific type of (Y) cells?

Answer 54

X = antigen-derived peptide CD-8 Y = T cells

Question 55

MHC Class II molecules present (X) to which specific type of (Y) cells?

Answer 55

X = antigen-derived peptide CD-4 Y = T cells

Question 56

The function of CD4/8 molecules, aka (X), on (Y) cells is to:

Answer 56

``` X = co-receptors Y = T ``` Enhance avidity of TCR:MHC binding

Question 57

CD4/8 molecules interact with which specific regions of (X)?

Answer 57

X = MHC molecules | Non-polymorphic regions

Question 58

MHC Class I pathway presents peptides derived from (intra/extra)-cellular pathogens.

Answer 58

Intracellular

Question 59

MHC Class II pathway presents peptides derived from (intra/extra)-cellular pathogens.

Answer 59

Extracellular (phagocytosed/endocytosed)

Question 60

MHC Class (I/II) pathway: the cytosolic protein is degraded into peptides by (X). The peptides are then transported across (Y) via (Z).

Answer 60

Class I; X = proteosome Y = ER membrane Z = TAP (transporter)

Question 61

MHC Class (I/II) pathway: within ER, peptides are preferentially associated with newly synthesized (Y).

Answer 61

Class I | Y = MHC Class I proteins

Question 62

MHC Class (I/II) pathway: the engulfed microbe is degraded into peptides by (X). The peptides are then transported across ER via (Y).

Answer 62

Class II X = proteases (in lysosome) NOT transported to ER!

Question 63

T/F: Both MHC Class I and II proteins are transported through the ER.

Answer 63

True

Question 64

(Inside/outside) ER, MHC Class (I/II) proteins are bound to (X), occluding the (Y).

Answer 64

Inside; Class II X = invariant chain (Ii) protein Y = peptide-binding cleft

Question 65

The invariant chain (Ii) protein prevents (intra/extra)-cellularly derived peptides from binding to the MHC Class (I/II) proteins.

Answer 65

Intracellularly | Class II

Question 66

An extracellular pathogen engulfed by macrophage will eventually activate (CD4/CD8) T cell, which functions to (X) by (Y).

Answer 66

CD4 (helper T cell); X = help macrophage kill ingested microbe Y = secreting cytokines

Question 67

An extracellular pathogen endocytosed by B cell will eventually activate (CD4/CD8) T cell, which functions to (X) by (Y).

Answer 67

CD4 (helper T cell); X = stimulate B cells to produce Ab (to attack extracellular pathogen) Y = secreting cytokines

Question 68

An intracellular pathogen are presented by (X) and will eventually activate (CD4/CD8) T cell, which functions to (Y).

Answer 68

X = MHC Class I proteins CD8; Y = kill infected cell