chpt 9
Terms
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3 similarites of Ig and TcR
2 differences -
Similariteis:
1. both in Ig domain superfamily members
2. both undergo gene rearrangement
3. both contain multigene families - main differences between TcR and BcR
- distinct recognition and effector mechanisms
- how many CDRs in each V chain of TcR?
- 3; because two V chains, total 6 CDRs
- what do CDRs bind to?
- MHC AND ANTIGEN
- how many multigene families encode the T cell receptor?
- 4; alpha, beta, delta, gamma
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gene segments for alpha and gamma:
for beta and delta: -
VJC
VDJC - what is the MAIN DIFFERENCE between TCR and Ig genes?
- only one or two Constant genes for TcR; no class switching, NO DIFFERENTIAL RNA PROCESSING
- 3 enzymes for gene rearrangement
- Rag 1 and 2, dsbr
- difference in gene rearrangement of TcR
- additional alternative joining of D gene segment in B and delta cuz of RSS arrangement; more diversity in TCR than Antibodies.
- 4 additional molecules necessary for interaction of TcR with Ag:
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CD3 complex
CD4
CD8
Adhesion Molecules - think of glue, adhesive strip - WHEN do adhesion molecules help TcR bind to Ag/MHC
- after interaction of the aforesaid; enhanced display of these molecules when the cell is activated allows longer tango
- allograft organ transplant
- tissue transfer between organisms of same species but different genes
- why do CTL's recognize allograft transplants, when they should only recognize SELF mhc???
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Cross-reactivity of TCR; the CTL binds to the foreign peptide/foreign MHC with LOW AFFINITY, but yet it does bind.
remember there is a lot more MHC1 on cells than MHC2; this overcomes the weak interaction. by sheer force of #