Immunology-Antigen Receptors Flashcards
What are the specific antigen recognition agents?
Immunoglobulin (Ig)/antibody TCR MHC class I and II
What two antigen recognizers are antigen-specific, thus confer specificity?
TCR and Ig/antibody
Where are the V domains located and what do they do?
Located nearest to the amino-terminal contribute to antigen-binding site, determines antigen specificity
What do C domains do?
Contribute to antibody function
What do antibodies consist of?
Two identical heavy chains and two identical light chains
What does the heavy chain consist of?
4 or 5 protein domains: amino-terminal V domain, 3-4 C domains
What does the light chain consist of?
One V and one C domain
What is the main function of the V domain?
determine specificity by amino acid composition
different composition=different folding to fit specific antigens
What is the main function of the C domain
determine biological functions of the antibody molecule (promote phagocytosis, binding complements, or mast cells, etc)
not variable, don’t bind antigen
secreted antibodies don’t possess this region
What are the five classes of heavy chain C domains?
IgM
IgG
IgE
IgA
IgD (humans and mice; expressed on B cell membranes, with IgM, never secreted)
True or false: specificity (V domain sequence) is related to antibody class
False; different classes of antibody can be associated with same V domains and have same specificity
What happens after IgM B cells are exposed to antigens?
Differentiate and synthesize other classes of immunoglobulin
Retain same V domains (specificity) expressed by parent B cell
Reg’d by T cell cytokines
What controls class switch?
cytokines from antigen-activated T cells
What are TCR made of?
Combo of either alpha-beta or gamma-delta chains
