1. Organization & Expression of Immunoglobulin Genes
Hugh B. Fackrell
Read chappter 7 of Kuby

2. Organization & Expression of Immunoglobulin Genes
Assigned Reading
Content Outline
Performance Objectives
Key terms
Key Concepts
Short Answer Questions

3. Assigned Reading
Chapter: 7 pp
Janis Kuby’s Immunology 3rd Ed

4. Content Outline Genetic models
Multigene Organization of Immunoglobulin Genes
Variable-Region Gene Rearrangements
Generation of Antibody Diversity
Class Switching in C region genes
Expression of Ig Genes
Regulation of Ig-Gene Transcription

7. Genetic models Germ line vs somatic mutation model
Dryer Bennett: Two gene model
Verification

11. Multigene Organization of Immunoglobulin Genes
lambda chain multigenes
kappa chain multigenes
heavy chain multigenes

16. Variable-Region Gene Rearrangements
V-J rearrangements of light chains
V-D-J rearrangements of heavy chains

20. Mechanisms recombination signal sequences
enzymatic joining of gene segements
RAG-1 RAG-2
Defects
Productive vs non productive gene rearrangements
Allelic exclusion

27. Generation of Antibody Diversity
multiple germ line gene segments
combinatorial V-J & V-D-J joining
junctional flexibility
P-nucleotide addition
N-nucleotide addition
Somatic hypermutation
Association of light & heavy chains

31. Class Switching in C Region Genes
Expression of Ig Genes
Differential processing of RNA transcripts of heavy chains
Membrane bound vs secreted Ig
Coexpression of IgM & IgD
Synthesis, assembly and secretion

33. Regulation of Ig-Gene Transcription
DNA rearrangement
Inhibition by T Cells

34. DONE!!!

35. Performance Objectives

36. Key Terms allelic exclusion, class switching,
combinatorial freedom of chain association,comibinatorial association of
gene segments, Constant (c) gene segments, Diversity (D) gene segemtns,
Palindromes, acceptor junctions, donor junctions, enhancers, exons,

37. 7-9 rule, 12-23 rule, Germline theory, somatic theory, imprecise DNA rerangement,
Insertion of random N regions, introns, Joining (J) gene segments,
junctional diversity, leader sequence, Membrane (M) exons), n regions
promotors, recognition sequences, spacer sequences, somatic hypermutation,
switch recombination. switch (S) regions, variable(V) gene segments

38. Key Concepts
Describe how the number and organization of immunoglobulin gene segements or exons contribute to the generation of antibody diversity
Draw the organization of Kappa light chain genes.
Draw the organization of Lambda light chain genes.

39. Draw the organization of heavy chain genes.
Describe the V-J joining for light chain genes in terms of the 7-9 and the rules
Describe the V-D-J joining of heavy chain genes in terms of the 7-9 and the rules.
Explain how allelic exclusion leads to cells that produce immunoglobulins with a single antigen binding site.

40. Describe how transcription controls immunoglobulin gene expression
Describe at least four mechanisms that contribute to antibody diversity
Describe the coexpression of IgM and IdD in terms of RNA processsing
Describe the mechanisms for class switching
Correlate B cell differentiation with immunoglobulin gene rearrangements

41. Short Answer Questions

42. Why is it important to have antibody diversity?
Differentiate between the germline theory and the somatic theory of generation of antibody diversity.
How are BOTH germline and somatic mechanisms sources of antibdoy diversity?
Why did the amino acid sequencing of antibody light chains lead Dryer and Bennet to abandon the one gene- one polypeptide theory and propose that two genes code for a single polypeptide?

43. Describe Tonagawa's approach to answering Dreyer and Bennett's hypothesis that two genes code for a single polypeptide.
In addition to showing that DNA seqments come together to form a functional antibody gene, Tonagawa's experiments showed two other things. What were they?

44. The phrases "race car", "Madam I am Adam" and "sex at noon taxes" represent pallindromes in the english language.
What are pallindromes in the genetic code and what is their importance in V region construction?
What are the two DNA recombinational events required to assemble a functional heavy chain V region gene?

45. The two DNA recombinational events required to assemble a functional heavy chain V region gene, are governed by the 7-9 and the rules. Explain.
Discuss four mechanisms that contribute to antibody diversity.
Describe the differential splicing of RNA that progresses from membrane bound IgM to secreted IgM.

46. Explain how a particular B cell can secrete different antibody isotypes, yet remain specific for the same epitope.
What are the two stages of class switching?
Dicuss allelic exclusion; what it is and how it is regulated.
List in correct chronological order the events leading to the synthesis of a Kappa light chain and its incorporation into an antibody molecule.

47. List in correct chronological order the events leading to the synthesis of a Gamma chain and its incorporation into an antibody molecule.