L4_Antibody Structure and Function Flashcards
Which chains contain variable regions and how many hypervariable regions do they have?
Both the light and heavy chain have variable regions with 3 hypervariable regions
Which chain can be variably labeled with Carbohydrates?
The heavy chain.
What chain defines the class of an antibody?
Heavy
Are the light and heavy chains made by the same or separate genes?
Separate.
What are the two types of light chains?
lambda and kappa
What are the different types of heavy chains how many subunits for each type?
M(5) , D(4), G(4), A(4), E(5)
On average what is the molecular weight of an antibody, what is the exception
~150kDa (IgM 1000kDa due to pentamer formation)
What subclass of Antibody is most abundant in the serum, least abundant?
IgG is most IgE is least
Which type of antibody is responsible for activating mast cells triggering an allergic reaction?
IgE
What types of antibody are mainly responsible for neutralization?
IgG and IgA (weak IgM)
What two types of IgG are mainly responsible for opsonization?
IgG1 and IgG3 (weak IgG4 and IgA)
What types of antibodies mainly activate the complement system?
IgM, IgG1, IgG3 (weak IgA and IgG2)
What type of antibody diffuses across the placenta?
IgG (IgG1 the strongest IgG2 the weakest)
What type of antibody can cross epithelium the easiest and is found in mothers breast milk? Which form of it?
IgA dimers
What type of antibodies diffuse into extravascular space?
All IgG and IgA monomers. (weak IgE)
What is the region called where the heavy chains are linked by disulfide bonds on IgG?
Hinge Region
Name the functions/capabilities of IgG
Toxin neutralizing, agglutinating, opsonizing, bacteriolytic (with aid of complement system)
Do immune cells have IgM receptors?
No
Name the functions/capabilities of IgM
Antigen receptor on B-cells and agglutinating. Only with the aid of complement can it be opsonizing or bacteriolytic (Immune cells do not have IgM receptors)
Does IgM have a hinge region?
NO
What chain is involved when IgM and IgA form multimers?
J Chain
What type of Ab is predominant in secretions?
IgA (dimers)
What are the main functions of IgA
agglutinating, neutralization, and opsonization
What piece of IgA aids in secretion and what does it do?
T-Piece resists acid hydrolysis
What does Papain do? What does Pepsin do?
Papain digests hinge region(3 fractions 1 Fc and 2 Fab). Pepsin digests heavy chain starting at C-terminus and ending at interchain disulfides (1fraction Fab2)
What are the residues in the variable region that do not vary much referred to as?
Framework residues
What does IgE do?
Immediate hypersensitivity, fixes to mast cells, mediates changes in vascular permeability.
What antibody is the most potent at complement fixation?
IgM
