Lecture 19

Question 1

Variable Domains Provide:

Answer 1

Antigen binding
- varying binding site changes antigen binding profile

Question 2

Constant Domains Provide:

Answer 2

1. Docking site for effector proteins
2. Extended presentation of V domains

Question 3

Ab secretion

Answer 3

IgA alpha C-Domain

Question 4

Parasite Attack

Answer 4

IgE epsilon C-Domain

Question 5

Placental X-ing

Answer 5

IgG gamma C-Domain

Question 6

BCRs and TCRs

Answer 6

1. > 107 B- and T- Cells
2. Immunorepertoire >106 B- and T- Cells
   ** each B- and T- cell expresses 100,000 copies **

Question 7

Germ Line Theory

Answer 7

1. An early hypothesis
2. Each antibody (BCR) is encoded by a gene

Question 8

ONE GENE = ONE PROTEIN

Answer 8

10^6 distinct BCR/antibodies
– 3,000 nucleotides in an individual Ab coding sequence

Question 9

BCR A.A Sequencing

Answer 9

1. Multitude of V domain sequences
2. Conserved C domain sequences
   - molecular shuffling

Question 10

Transposons ‘jumping’ genes

Answer 10

1. 1948; corn DNA
2. DNA segments ‘cut-n-pasted’
3. DNA segments ‘copied-n-pasted’
   Generally in NON-CODING regions

Question 11

DNA Recombination

Answer 11

Potential mechanism for generation antibody diversity

Question 12

Somatic Cell Recombination

Answer 12

1965; Dreyer and Bennett
1. Heavy chains and light chains on separate genes
2. V- and C- regions DNA`= recombined in B-Cells; V-C gene

Question 13

Susumu Tonegawa

Answer 13

1. Isolate DNA
2. Cut DNA at specific sites
3. Segregate cut DNA by size
4. Blot DNA onto nitrocellulose paper

Question 14

DNA Migration: Germline

Answer 14

Constant and Variable on different restriction fragments

Question 15

DNA Migration: Plasma Cells

Answer 15

Constant and Variable on the same restriction fragments

Question 16

Immature B-Cell

Answer 16

1. DNA Recombination: V Domain
2. Lymphoid Organ: Bone Marrow

Question 17

Activated B-Cell

Answer 17

1. Somatic Hypermutation: V Domain
2. Ig Class Switching: C Domain
3. Lymphoid Organ: Germinal Centers

Question 18

Variable Domains

Answer 18

Coded by V-, J-, and D- segments

Question 19

Human VkJkCk Genes

Answer 19

1. 34-48 functional variable genes
2. 7 functional joining regions

Question 20

Human VIJICI Genes

Answer 20

1. 33 function VI regions
2. 7 pre-assigned JICI regions
   
   • J and C regions recombine
   • recombination only downstream

Question 21

Human V-D-J-C Genes

Answer 21

1. > 38 functional VH regions
2. 23 functional D regions
3. 6 functional J regions
4. 8 functional C regions
   
   • Antibody class
   • effector functions

Question 22

Recombination Signal Sequences

Answer 22

Conserved DNA sequence motifs that enzymes use to target sites of DNA recombination

Question 23

RSS Conserved

Answer 23

1. Heptamer (size and sequence)
2. 23bp/12 bp sizes
3. nonamer

Question 24

RSS Less Conserved

Answer 24

23 bp/ 12 bp spacer sequences

Question 25

Recombination Heavy Chain DNA

Answer 25

1. D-J always first
2. V-D always second

Question 26

RAG1/2 Recombinase

Answer 26

Expressed exclusively in T- and B- Cells

Question 27

RAG1

Answer 27

Forms a complex with RSS

Question 28

RAG2

Answer 28

Stabilizes the RSS: RAG1 Complex

Question 29

RAG1/RAG2

Answer 29

Initiates the recombination (nicks DNA)

Question 30

Terminal deoxynucleotidyl Transferase (TdT)

Answer 30

1. Expressed exclusively in T- and B- Cells
2. Adds untemplated nucleotides to free 3’ ends