B and T cell receptors
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How many signals are req for complete lymphocyte activation?
- 1. interaction w/ specific antigen
- 2. interaction w/ co-stimulatory molecules
B cell receptors for antigen; family of glycoproteins
What are the two forms of antibodies?
ONLY as membrane bound receptor, NOT secreted
How are TCR diff from antibodies?
- 1. recognize Ags only
- 2. do not recog whole Ag
- 3. are only in mem bound form
How many chains make up an Ig molecule? What bonds exist?
2 identical H chains, 2 identical L chains
- interchain disulfides: link peptide chains, i.e. H to L
- intrachain disulfides: link within peptide chains, i.e. w/in H chain
delta heavy chain class
gamma heavy chain class
epsilon heavy chain class
alpha heavy chain class
alpha 1 or 2
What are the light chain classes?
Why is the hinge region sig in antibody structure?
it's proline rich characteristic allows the antibody arms to bend when binding to antigen
has interchain disulfides, protease sensitive
Variable region domain
first 110 amino acids at AMINO TERMINAL of H and L chains (similarity to histones?)
least variable of all domains and allows specificity to antigens
Constant region domain
- H chain: 3 or 4 domains
- L chain: 1 domain
consistent w/in a class
L chain structure
each domain has 2 anti-parallel B-pleated sheets, linked by disulfide bond...makes B barrel! Loops that stick out into env form antigen binding sites
- "hydrophobic sandwich":
- bread=B sheets
- tuna=phobic parts of AA
- toothpick=intrachain disulfide
- complementarity determining regions or hypervariable regions: loops btw B pleated sheets
- -complementary to structure of antigen that binds
conserved seq btw CDRs that correspond to B sheets and maintain integrity of Ig
How many CDRs do H and L chains in humans have?
3 each...6 total
What characteristics make a for a good fit?
low repulsion, high attraction
What characteristics make for a poor fit?
low attraction, high repulsion
What is affinity dep on?
chem features di gruppe coppie: H bonds, electrostatic, VdW, phobics
strength of interaction that involves antibodies binding to a single antigen by more than one binding site at the same time
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