14- Structure and Function of Antibodies Flashcards
List the different types of heavy chains of an antibody
Alpha, epsilon, gamma, delta, mu
What are the types of light chains of an antibody?
Lambda or kappa
The heavy chains of an antibody determine the class (isotype) of an antibody. Why?
Because the Fc portion if determined by the type of heavy chain region
- activity of the Ig is dependent on the receptors of the Fc region on different cells
Define the hyper variable regions (CDRs) of an antibody
An antigen binding site consists of VH and VL domains. Within these domains are hypervariable regions. Amino acids in these regions vary significantly and bind to the antigen. Hypervariable regions are not next to each other in a linear structure but come together to form an antigen binding site when the protein folds
- Complimentarity determining regions (CDRs) are made up of hypervariable regions
List the characteristics and primary functions of IgG.
-4 HC domains
- found in the blood stream and interstitial fluid in tissues
- high concentrations in colostrum of large animals
- 1/2 life of 3 weeks and 80% of total serum
- functions: complement activation, neutralization of viruses and toxins, opsonization, systemic immunity in newborn, antibody dependent cell mediated cytotoxicity
** can easily get out of circulation because it is small compared with IgM which is large
List the characteristics and primary functions of IgM.
- pentamer
- heavy chain has 5 domains
- held together by disulfide bonds and J chain
- can bind 10 identical epitopes
- found in the bloodstream
- first class of antibody produced in a primary response
- functions: complement activation, aggultination**
List the characteristics and primary functions of IgA.
- dimer
- 4 heavy chain domains
- held together by a J chain
- most of it is found on mucosal surfaces
- secretory component is added to the molecule as it is transported to the mucosal surface
- functions: found on mucosal surfaces where it can neutralize toxins and block entry of pathogens and it is found in mothers milk and provides intestinal immunity to neonate
List the characteristics and primary functions of IgE.
- five domains in heavy chain
- a lot of polysaccharide attached to heavy chain
- Fc portion of IgE has a high affinity for the Fc receptor on mast cell
- Binding of antigen to the IgE on a mast cell can result in mast cell degranulation
- most IgE is found on mast cells and the concentration in plasma is low
- functions: important in parasite defense, mediator of immediate hypersensitivity
List the characteristics and primary functions of IgD.
- found on B cell surfaces and has a regulatory function
- Important in B cell development
All immunoglobulins originate as what?
B cell antigen receptors (BCRs) and shed into body fluids
_____ is the predominant immunoglobulins in serum and is mainly responsible for systemic defense.
IgG
_____ is a very large immunoglobulins and mainly produced during a primary immune response.
IgM
_______ is the immunoglobulin produced on body surfaces. It is responsible for the defense of the intestinal and respiratory tracts.
IgA
____ is found in very small quantities in very small quantities in serum and is responsible for immunity to parasitic worms and allergies
IgE
______ is found on the surface of immature lymphocytes
IgD
