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| 3684326107 | TCR Structure | αβ - 95% γδ - 5% Extracellular α1 and β1 domains are variable Extracellular α2 and β2 domains are constant There are also transmembrane domains and short intracytoplasmic tails The two TCR chains are connected by a disulfide bond between constant sequences |  | 0 |
| 3684346112 | Variable domains of TCR | α1 and β1 The variable domains contain 3 hypervariable regions (CDR1, 2 and 3) similar to the variable domains of Igs | 1 | |
| 3684356673 | TCR genes | There are four TCR multigene families (one for each of the receptor chains): α, β, γ, and δ The α and δ loci are one chromosome 14 The β locus is on chromosome 6 The γ locus is on chromosome 13 Functional TCR genes are produced by rearrangements of V and J segments in the α and δ chain genes and between V, D, and J in the β and γ chain genes | 2 | |
| 3684384917 | Rearrangement- V (D) J recombination | Gene rearrangement for α and β The α-chain DNA undergoes a variable-region Vα-Jα joining The β-chain DNA undergoes two variable region joinings. Dβ to Jβ first and then Vβ to DβJβ T cells express RAG1/2 recombinase enzyme to catalyze V-J and V-D-J joining during TCR-gene rearrangement | 3 | |
| 3684414736 | TCR complex: TCR/CD3 | TCR associates with CD3, forming the TCR-CD3 membrane complex CD3 is required for the surface expression of TCR CD3 is also required for the initiation of the transduction signals as TCR has a very short intracellular tail that cannot signal |  | 4 |
| 3684448193 | CD3 complex invariant chains | 5 total (γ, δ, ε, ζ and η) that form 3 types of dimers: 1) heterodimer: γε 2) heterodimer: δε 3) homodimer of ζζ (90%) or a heterodimer of ζη γ, δ, and ε have Ig-like extracellular domains, transmembrane domain and intracellular domains The intracellular domains contain immunoreceptor tyrosine based activation motif (ITAM), important for signal transduction (Note: γ, δ, and ε have 1 and ζ and η have 3 | 5 | |
| 3684484820 | CD4 receptor | CD4 is a monomeric membrane glycoprotein with 4 extracellular Ig-like domains, a transmembrane domain, and a long cytoplasmic tail containing serine (which can be phosphorylated) The extracellular domains of CD4 bind to the β2 domains of class II MHC |  | 6 |
| 3684494541 | CD8 receptor | CD8 is a disulfide-linked heterodimer αβ. The chains contain a single extracellular domain, a transmembrane domain, and a cytoplasmic tail, containing several phosphorylation sites The extracellular domains of CD8 bind to α3 of class I MHC |  | 7 |
| 3684511663 | TCR signaling | Engagement of MHC-peptide initiates processes that lead to assembly of signaling complex CD4/8-associated p56LCK phosphorylates ITAMs of zeta chains, create docking site for ZAP-70 ZAP-70 phosphorylates a number of adaptor molecules that recruit components of several signaling pathways Signaling pathways induced by ZAP70 promote T cell activation and differentiation |  | 8 |
| 3684530214 | Accessory membrane molecules | Accessory membrane molecules bind to other ligands on APC (Note: Tc cells do the same to ligands on target cells) and strengthen adhesion 1) CD28 on Th cells interacts with B7 (CD80/86) on APC. This interaction serves as a costimulatory signal for T cell activation 2) CD2 on Th cells to LFA-3 on APC 3) LFA1 on Th cells to ICAM-1 on APC | 9 | |
| 3684543139 | B cell receptor (BCR) structure | Since all mIgs have very short cytoplasmic tails which can not generate a signal, they associate with two Iga/IgB heterodimers with long cytoplasmic tails to form BCR that allows signal generation |  | 10 |
| 3684570908 | B cell coreceptor | Composed of 3 molecules: 1) CD19 (long cytoplasmic tail) 2) CR2 (CD21, receptor for C3d) 3) TAPA-1 (CD81) CR2 binds to the complement-coated Ag bound to the BCR (C3d/Ag/BCR) that results in the phosphorylation of CD19 to induce signal transduction pathway |  | 11 |
| 3684581616 | Combinatorial Joining | V(D)J rearrangement brings together multiple germline gene segments that may combine randomly, and different combinations produce different antigen receptors that contributes to the diversity of TCR and BCR | 12 |
