B and T cell receptors

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B and T cell receptors
2011-08-17 17:02:18
cells immunology

MS1/Mod 1: immunology; B and T cell receptors
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  1. How many signals are req for complete lymphocyte activation?
    • two
    • 1. interaction w/ specific antigen
    • 2. interaction w/ co-stimulatory molecules
  2. Antibodies
    B cell receptors for antigen; family of glycoproteins
  3. What are the two forms of antibodies?
    • Membrane bound
    • Secreted
  4. TCR
    ONLY as membrane bound receptor, NOT secreted
  5. How are TCR diff from antibodies?
    • TCR...
    • 1. recognize Ags only
    • 2. do not recog whole Ag
    • 3. are only in mem bound form
  6. 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
  7. IgM
    mu heavy chain class
  8. IgD
    delta heavy chain class
  9. IgG
    gamma heavy chain class

  10. IgE
    epsilon heavy chain class
  11. IgA
    alpha heavy chain class

    alpha 1 or 2
  12. What are the light chain classes?
    • Kappa
    • Lambda
  13. 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
  14. 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
  15. Constant region domain
    • H chain: 3 or 4 domains
    • L chain: 1 domain

    consistent w/in a class
  16. 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
  17. CDRs
    • complementarity determining regions or hypervariable regions: loops btw B pleated sheets
    • -complementary to structure of antigen that binds
  18. Framework regions
    conserved seq btw CDRs that correspond to B sheets and maintain integrity of Ig
  19. How many CDRs do H and L chains in humans have?
    3 each...6 total
  20. What characteristics make a for a good fit?
    low repulsion, high attraction
  21. What characteristics make for a poor fit?
    low attraction, high repulsion
  22. What is affinity dep on?
    chem features di gruppe coppie: H bonds, electrostatic, VdW, phobics
  23. Avidity
    strength of interaction that involves antibodies binding to a single antigen by more than one binding site at the same time