Lecture 7: Generation of lymphocyte antigen receptor repertoire

Question 1

The TCR is composed of an ____ and ____ chain and its effector function is ____

Answer 1

alpha, beta
T Cell

Question 2

What is the approximate immuglobin repertoire in humans?

Answer 2

10^11-10^15

Question 3

What is the repertoire limited by at any one time?

Answer 3

B-cell population size and an individual’s exposure history

Question 4

Antibody genes are made up of _____

Answer 4

segments

Question 5

In mature lymphocytes, gene segments are brought together by ________, which means _______

Answer 5

somatic recombination; at random

Question 6

The variable region of light chain is composed of 95-101 aa ___ segment and about 13 aa ___ segment

Answer 6

V (variable); J (joining)

Question 7

The heavy chain has ___ segment in addition to V and J

Answer 7

D (diversity)

Question 8

What is recombination signal sequence? (RSS)

Answer 8

unique sequences that guide the process of choosing V and J (and D) domains,
heptamer, 23 aa, nonamer
nonamer, 12 aa, heptamer
in accordance with major/minor grooves of DNA

Question 9

RSS in lambda chain

Answer 9

V, 23RSS - - 12RSS, J

Question 10

RSS in kappa chain

Answer 10

V, 12 RSS - - 23 RSS, J

Question 11

RSS in heavy chain

Answer 11

V, 23 RSS – 12RSS, D, 12RSS - - 23 RSS, J

Question 12

RSS binds to ____ and _____ that will ____ dsRNA

Answer 12

RAG1 and RAG2; cut

Question 13

dsDNA breaks caused by RAG1 and 2 can be repaired by _____

Answer 13

NHEJ

Question 14

RAG1 binds to RSS by recognizing ______ sequence

Answer 14

nonamer

Question 15

_____ has endonuclease activity to make 2 ssDNA breaks on the ___ side of RSS

Answer 15

RAG2; 5’

Question 16

ssDNA break repaired by ________ with complementary strand

Answer 16

hairpin formation

Question 17

Flush dsDNA break formed at ________

Answer 17

the ends of the heptamers

Question 18

Proteins involved in NHEJ

Answer 18

Ku70/Ku80/DNA/PKcs

Question 19

_____ makes functional gene

Answer 19

DNA ligation

Question 20

_______ complex opens hairpin

Answer 20

DNA-PK:Artemis

Question 21

____ modifies hairpin by randomly adding/removing nucleotides

Answer 21

TdT

Question 22

____ ligates DNA together

Answer 22

DNA ligase IV and XRCC4

Question 23

What are the 4 ways to generate diversity in B cells?

Answer 23

Combinatorial diversity
Junctional diversity (TdT)
Random pairing of heavy/light chains
Somatic hypermutation

Question 24

Combinatorial diversity is responsible for ____ combinations in B cells/antibodies and is _____ in T cells

Answer 24

3x10^6
higher

Question 25

CDR 1 and 2 regions are encoded by ___ domain

Answer 25

V

Question 26

CDR3 diversity results from _____ and falls at the ____ boundary

Answer 26

random insertions/deletions of nucleotides; V-J (or V-D)

Question 27

_____ diversity is produced at a considerable cost, as 2/3 recombinations will result in nonfunctional proteins

Answer 27

Junctional

Question 28

What are the two classes of nucleotides incorporated?

Answer 28

Palindromic and non-templated (P and N)

Question 29

DNA-PK and Artemis complex generate _______ by opening up hairpins

Answer 29

P nucleotides

Question 30

TdT adds _____

Answer 30

N nucleotides

Question 31

After the addition of about 20 N nucleotides, ____ can occur

Answer 31

complementary base pairing

Question 32

SHM occurs via ______ of an optimal _______ with enhanced antigen binding capability

Answer 32

selection; structure

Question 33

SHM can produce two ______ sequences with ___ affinity for the ________ epitope

Answer 33

different; high; same

Question 34

____ will force presence of nicks and repair of DNA so that different nucleotides are inserted

Answer 34

AID

Question 35

_______ occurs via AID

Answer 35

SHM

Question 36

AID is only present in ______

Answer 36

B cells

Question 37

AID works by deaminating __ to ___

Answer 37

C -> U

Question 38

What removes uracil and ribose from DNA after AID deaminates it from cytidine?

Answer 38

UNG (Uracil-DNA glycosylase) APE1 (apurinic/apyrimidinic endonuclease)

Question 39

alpha chain in T cell receptor

Answer 39

Valpha, J alpha, C alpha

Question 40

Beta chain in TCR

Answer 40

Vbeta, Dbeta, Jbeta, Cbeta

Question 41

TCR recognizes a sequence of ____ aa

Answer 41

9

Question 42

The ____ of TCR makes contact with bound peptide and is responsible for the ____ variability

Answer 42

CDR3; most

Question 43

What cells does SHM occur in?

Answer 43

B cells only NOT T cells

Question 44

In T cells CDR3 variability comes from ______

Answer 44

P and N nucleotides

Question 45

In T cells, CDR1 and 2 variability comes from _____

Answer 45

germline (combinatorial)

Question 46

___ variability is unique to Igs due to their effector function

Answer 46

Constant region

Question 47

Isotype switching is guided by _______

Answer 47

switch regions mu