Lecture #5

Question 1

The structures of BCR and TCR

Answer 1

Question 2

Structural differences between secreted Ig and BCR

Answer 2

Question 3

Isotype of an Ab

Answer 3

Different glycosylation pattern on the constant region of the heavy chain

miu, gamma, alpha, epsilon, delta

Question 4

Allotype of an Ab

Answer 4

WIthin classes (isotypes) one SNP in the gene coding for the isotype is creating more variants

Ex: IgG1,2,3,4

Question 5

Idiotype of an Ab

Answer 5

Changes in the variable region

Question 6

Binding sites on immunoglobulins

Answer 6

Groove between CH1 and VH for the binding of C3b C4b

CH2 binding site for the head of C1q

Fc region for FcR

Question 7

CDR

Answer 7

Complement determining regions on Abs or TCRs

Composed of 3 N’ terminal loops in the variable region which are highly variable and can bind non covalently to the Ag

Also called HV1, HV2, HV3

Question 8

CDR in TCR

Answer 8

HV1 and HV2 bind specific AA on the MHC

HV3 binds specific AA on the Ag

Question 9

Genetic modifications in order to increase the pool of possible BCRs and TCRs

Answer 9

1. Somatic gene rearrangment
2. Junctional diversity

Question 10

Ig heavy chain genes are found on chr ____ lambda light chain on chr_____ and kappa on chr_____

Answer 10

14

22

2

Question 11

What is the constitution of the gene goding for Ig heavy chain (general)

Answer 11

Question 12

Somatic gene rearrangment

Answer 12

Also called VDJ recombination

In the bone marrow, CLP is matured to B cell and in , the process of BCR synthesis, one gene is chosen from each V, D and J genes consisting the variable region

The light chains undergo the same recombination only with V and J

Same happens for TCR in the thymus during T cell maturation

(beta chain has VDJ alpha chain has VJ)

Question 13

Junctional diversity

Answer 13

Mediated by RAG1/2 recombinases

Only expressed in developing lymphocytes

RAG complex recognize RSS recombination signal sequences at the junctions between VDJ genes

1. Binding to RSS
2. Hair pin formation and cleavage by artemis endonuclease
3. Addition of random nucleotides and ligation

Question 14

The principle of allelic exclusion

Answer 14

During B cell maturation only one gene for BCR is expressed, either maternal or paternal the other one is inhibited

Question 15

Junctional diversity defect

Answer 15

Ommen’s syndrome

Partial activity of RAG1/2/Artemis

There will be no B cells and low amount of T cells