T Cell Receptor Hugh B. Fackrell Nov 9, 1998
T Cell Receptor • Assigned Reading • Content Outline • Performance Ojectives • Key terms • Key Concepts • Short Answer Questions
Assigned Reading • Chapter: 11 pp 264-283 • Janis Kuby’s Immunology 3rd Ed
Early Studies Structure of T cell Receptors TCR Genes Cloning TCR multi gene families T Cell Receptor Complex TCR-Peptide-MHC Complex Associative recognition hypothesis Formation of ternary complex Alloreactivity of T Cells Content Outline
Early Studies • self MHC restriction • isolation of t cell receptors
Hetero dimer 95% Alpha: Beta 2-5% Gamma: Delta Variable Domains 3 HVR Constant Domains Transmembrane region (Tm) ~20 AA Cytoplasmic Tail (CT) 5-12 amino acids TCR: Structure
Cloning TCR Genes DNA subtractive hybridization
TCR multi gene families: Outline • Variable region rearrangements • TCR DNA rearrangements • Allelic exclusion • Structure of rearranged TCR genes • Generation of TCR diversity
TCR Multigene Families: General • 4 multigene families • one for each chain • Gene rearrangements • Alpha: Gamma - V J exons • Beta: Delta - V D J exons • Chain exclusion
T Cell Receptor Complex • CD4 & CD8 coreceptors • Accessory membrane molecules
Associative recognition hypothesis • Formation of ternary complex • Affinity of TCR • Peptide topology
Key Terms • CD2, CD4, CD8, CD28, CD54, CD58, integrins, T cell receptors, • alpha beta TCR, gamma delta TCR, Transcription factor • NF-KB
Key Concepts • Draw the structure of the T Cell Receptor (TCR) • Compare and constrast the structure of TCR with B cell receptor • Draw a diagram of the T cell receptor gene organization
Describe the stragetgies for diversification of T Cell Receptors • Describe how a T cell Receptor recognizes an antigen • Describe the TCR-Antigen-MHC complex
Hedrick and Davis used the technique of subtractive hybridization to isolate cDNA clones encoding for the T cell receptor. • Briefly explain the method of subtractive hybridization. • State why this method was so important in the characterization of the TCR.
What does it mean to say that TCRs belong to the Ig supergene family? • Briefly describe the heterodimeric structure of the TCR. • TCR genes use the same strategies as antibody genes to develop receptor diversity; however, TCR genes do not exhibit somatic hypermutation. Why? • The TCR is closely assoicated with another surface protein complex. What is its name and function?
Describe the three way complex that occurs during antigenic recognition by T cells. • T cells can react only with protein fragments. • What is this process called? • How does it occur? • Which pathway leads to antigen interaction with MHC-I molecules? • Which pathway leads to interaction with MHC-II molecules?
What are accessory molecules? • Give some examples. • Briefly discuss how they may be involved in antigen recognition by T cells.