Card Set Information
Combinatorial joining of gene segments
The joining of gene segments to form the components for Ig receptors.
Human kappa receptor formation
DNA has various V (variable) and J (joining) regions.
1) Transcription causes specific V, J and C (constant) region to come together.
2) RNA splicing removes excess RNA.
3) Translation produces light chain.
Heavy chain receptor formation
V, D, and J region.
1) D and J form first, and then V joins DJ.
2) 51 V, 6 J, and 27 D different genes.
During joining of antibody gene fragments, nucleotides are lost from the ends of recombining gene fragments. Insertions can happen too.
6 alleles total, 3 from paternal and 3 from maternal.
Only two will be activated and the others will not be used during B cell development.
B cell development
1) Combinatorial joining of gene segments.
2) Junctional diversification during joining of gene segments.
3) Combinatorial joining of light/heavy chains (allelic exclusion).
4) Somatic hypermutation
2) Defend vertebrates against infection.
3) Membrane bound receptors and never secreted.
1) Heterodimer of a and b chain
2) Each chain has 2 Ig like domain
3) Each chain encoded by V, D, and K
4) No somatic hypermutation.
5) Low binding affinity (Ka ~10^6 L/mol).
Cytotoxic T cell
Directly kill cells infected with pathogen.
Helper T cells
Stimulate response of others such as macrophages, B cells, and Tc.
T cell responses vs. B cell responses
1) Once T cell activated to become
, they act only at short range with target cell and either kill or signal.
2) Antigen causes proliferation only when it is displayed by antigen-presenting cells.
Antigen presenting cells in lymphoid organs
1) Dendritic cells (innate)
2) Macrophages (innate)
3) B cells (humoral)