Antigen Recognition by B cell Receptors Flashcards
What are the antigen-recognition molecules for B cells?
immunoglobulin
Define an antigen
any substance that can bind an anitbody
Define and immunogen
any substance that can elicit an immune response
When does the adaptive response occur?
after 96 hours
What do T cells recognise?
peptides from pathogens presented by MHC on APCs
Role of the variable domain on immunoglobulins
Bind a variety of antigen
Role of constant domain of immunoglobulins
Recruits other cells/molecules
2 types of light chains
lambda and kappa
5 types of heavy chains
M,D,G,A,E
How does the C-terminus change between BCR and antibody
hydrophobic in BCR
hydrophilic in antibody
Subdivisions of the variable region
Hypervariable region
Framework region
Other name for HV regions
Complementarity determining regions (CDRs)
Role of the FR regions
Forms a structure which serves as a scaffold to hold the HV resions in position to contact antigen
Function of antibodies
To bind pathogens and facilitate their removal
Different types of binding sites
- groove
- extended surface
- protruding surface
What type of chemical force exists between antibody and antigen?
non-covalent
- hydrogen bonds bind over a wide SA
- VDW, electrostatic and hydrophobic add to strength and specificity of binding
What can disrupt an antibody-antigen interaction?
high salt conc
extreme pH
detergents
competition
What is somatic recombination?
A mechanism of genetic recombination in the early stages of Ig and TCR production of the immune system
Process of VDJ recombination
- germline DNA
- D-J rearranges and DNA joined
- V-J or V-DJ joined
- transcription of primary transcript RNA
- splicing to mRNA
- translation
Difference between heavy and light chain somatic recombination
light chain is only V-J
What guides DNA rearrangement?
Recombination signal sequences (RSS)
Enzyme complex that carry out VDJ recombination
VDJ recombinase
lymphoid tissue specific enzymes that carry out VDJ recombination
RAG-1 and RAG-2
Other enzymes involved in gene rearrangement
- DNA dependent protein kinase (DNA-PK)
- artemis (opens haripin to reveal ssDNA)
- DNA ligase IV (joins DNA ends)
