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Reminders. Animations on blackboard & web site. CD- “Clusters of Differentiation”. WALKER BIOLOGY CLUB MEETING & GUEST SPEAKER!!. Dr. Larry Grand from N.C. State’s Plant Pathology Department will be speaking!
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Reminders • Animations on blackboard & web site. • CD- “Clusters of Differentiation”
WALKER BIOLOGY CLUB MEETING & GUEST SPEAKER!! Dr. Larry Grand from N.C. State’s Plant Pathology Department will be speaking! Come hear about the Plant Pathology Graduate Program at N.C. State, as well as graduate programs & applications in general! February 27, 2008 5:00 p.m. in Room 210 Pizza & Drinks Provided
Antigen Processing & Presentation The exogenous pathway continued
Cathepsins- S & L: acid proteases
-Cathepsins S & L: acid proteases
MHC class II compartments- (MIIC) • 2-4 hrs to travel to endosome / phagosome.
What will happen if there is no infection? • What would happen if a pathogen lives inside the phagosomes of the macrophage? • Leishmania sp • Mycobacterium sp • Coxiella burnetti.
The two classes of MHC are differentially expressed on cells:
The TCR p. 68
3 Dimensional Structure of the a/b TCR: • CDR or HV regions
CD3 Complex CD3 heterdimers Epsilon-delta Epsilon-gamma Invariant accessory chains. The TCR interacts with other proteins to make the TCR Complex: • Zeta/zeta homodimer
Coreceptors function: CD4 recognizes & binds to the class II MHC. CD8 recognizes & binds to the class I MHC. Increase cell signaling event 100 fold. hinge The TCR complex requires coreceptors to be active: Fig. 3.10, p. 74, 2nd edition
How does the TCR complex Interact with the MHC-antigenic-peptide?
The TCR must recognize & bind to both the MHC molecule & the foreign peptide.
Light & dark blue- beta chain CDR1 & CDR2 Light & dark purple- alpha chain CDR1 & CDR2. Yellow- alpha chain CDR3 Green- beta chain CDR 3 Red- HV4 of beta chain. Dark Yellow- peptide in MHC.
Vb interacts with MHC-a1 & carboxy terminus of peptide. Va interacts with MHC-a2 & amino terminus of peptide. peptide a1 MHC a2
MHC alpha 1 MHC alpha 2 alpha & beta CDR3 make most contact with Ag peptide.
TCR- beta CD8 binding is distally located from the TCR binding area. TCR alpha MHC alpha CD8 alpha& beta MHC b-2
CD4 D1 binds to the b2 subunit in a hydrodphobic crevice between beta 2 & alpha 2 on the MHC class II. D1
CD4 D1 binds to the b2 subunit in a hydrodphobic crevice between beta 2 & alpha 2 on the MHC class II. alpha beta D2 D1