What makes an Ig flexable?
disulfide bridge (hinge region)
What Ig have 4 C regions?
IgM and IgE
What Ig are monomers when membrane bound?
All of them
Which Ig forms can form a dimer?
IgA
What is the hypervariable region?
The region at the tip of the variable region that binds to the epitope of the Ag
Five classes of Ig
IgA, IgE, IgD, IgM, IgG
What is an antigen that contains more than one epitome called?
Multivalent
What forces are involved in AB:AG binding?
Electrostatic, van Der Waals, Hydrophobic, Hydrogen. (Non-covalent)
How are monoclonal antibodies made?
Isolate B cells from animals, immortalize it in a tumor cell to form a hybridoma
What is somatic recombination?
The process of choosing one of many gene segments to form an econ that can be transcribed (V, D, J segments).
Light chains have V and J
Heavy chains have V,D, and J
Where are the gene segments encoded for Its?
Chromosome, 22, 2, and 14
What is RSS?
Somatic recombination is directed by RSS that flank V,D, and J segments. It provides a target for enzymes to cut and rejoin the gene segments. (V (D) J recombinase).
What is RAG (1 & 2)
Recombination activating genes (RAG). Forms the DNA into a hairpin, then cleaves and rejoins it
What is junctional diversity?
When RAG enzymes join the gene segments.
What is TdT?
If nucleotides need to be added to recombine segments, TdT is used
What is the overall BCR diversity?
4.8x10^13
How is SCIDs formed?
Lack of RAG enzymes (no functional T or B cells)
What are the 2 AB that are expressed on B cells?
IgM and IgD (called coexpression)
What is somatic hypermutation?
Process that increases diversity in Ig after the B cell encounters its Ag. Causes random point mutations
What is AID
Converts cytokine to uracil that causes a mutation to happen changing uracil to another DNA nucleotides
What is class switching dependent on?
AID
What allows IgM to be a pentameter or IgA to be a dimers?
A J chain
Best neutralizing Abs
IgG 1-4 and IgA
Best opsonizing
IgG1,3,4 and IgA
Sensitization for NK
IgG1 and IgG3
Sensitization for mast
IgE, IgG1 and IgG3
Complement activation
IgM, IgG 1-3, and IgA
TP across epithelium
dimeric IgA and some IgM
TP across placenta
IgG (1-4)
Diffusion into extravascular spaces
IgG, monomeric IgA, IgE
Info about IgM
-First AB produced during primary IR.
-Low affinity, but due to multiple binding sites, has higher avidity.
-Good complement activator, not a good opsonin
- Does not cross easily into extravascular spaces or MM
Info about IgG
- Most abundant in blood
- Smaller and more flexible (can cross into extravascular space)
- Crosses placenta
- Higher affinity than IgM
-IgG1 and IgG3 are opsonins for phagocytic cells
Info about IgA
- Monomeric IgA in serums (MM have limerick)
- IgA's found in sweat, breast milk and tears
- Can last longer than other Ig's because of secretory component present
Info about IgE
First exposure to Ag (pollen, parasite) results in IgE production.
- Mast cells
What are TCRs similar to?
Fan region on the Ig
Two major types of TCR
Alpha beta, and gamma delta.
What are different about TCR compared to BCR
No somatic hypermutation, only 1 constant region, only membrane bound, only used for recognition