Antibodies Part I- Diebel Flashcards
What is the H Chain?
Heavy Chain
what is the L chain?
Light Chain
What are kappa and Lambda chains?
They are the two types of light chains. Each antibody will only use one of these
What is the hinge region? Why is it important?
Region between Fabs and Fc, results in a buldging of the structure when bound to something…..which helps with
- binding phagocytic cells that have Fc receptors
- C1q of the complement region becomes exposed and binds to two adjacent Fc’s of IgG to become activated….IgM can activate complement alone because it is pentameric (need the bend to expose the C1q headpiece)
What is Fab, F(ab’)2, and Fc?
F(ab’)2 is the top part “V”
Fab is half of the “V”
Fc is the bottom of the “Y”
Using Papain you can break down aby into tow Fab and one Fc.
Using Pepsin you can break it down into one F(ab’)2 and one Fc’
What does valence mean?
Basically means how many things it can bind to…..each Fab can bind an epitope…..so IgG has a valence of 2…..IgA has a valence of 4…..IgM is weird and has a valence of 5 (theoretically it would be 10 because it is a pentameric antibody)
What are hypervariable regions?
Hypervariable regioins or (complementarity-determining regions) are in the V domain and have the most variability….this is the actual binding site for antigen…..this is made up of a light and heavy domain.
What are all these VL, CL, VH, and CH all about?
They indicate whethere the domain is variable (V) or constant (C) and light/heavy chain….chains are held together by disulfide bonds.
What is unique about IgE and IgM structure?
They both have J chains that hold them together.
What is unique about IgD?
It is only found in the membrane bound flavor and only found in naive B cells
What happens in class switching?
The heavy chain changes but the L chain stays the same
what are isotypes, ideotypes, and allotypes?
Isotypes- basically means the different classes (IgG1, IgG2, etc)
Allotypes- minor allele differences in the sequence of immunoglobulins.
Idiotypes- antibody’s unique binding site
What are the different antibody classes and functions?
IgG- main aby in blood and tissue, binds stuff and activates complement
IgA- dimer, released into secretions
IgM- first aby in serum after immunization, good at activating complement, pentameric
IgD- not really known, receptor on naive B cells
IgE- causes type I hypersensitivity, resistance to helminth infections
Can you just make IgG from the get go?
No! You need to make either IgM or IgD and then undergo CSR to get to IgG!
What is the structural difference between IgG1 and IgG3? Why is this important?
IgG3 has a much larger hinge region so it is better at complement binding/activation…..
