T Cell Receptor Gene Family

Abstract

The T cell receptor (TCR) is responsible for antigen recognition by T lymphocytes. Two types of TCRs defined by their component chains, TCRαβ and TCRγδ, are mutually exclusively expressed by αβ T cells and γδ T cells. The TCRα, β, -γ, and -δ polypeptide chains are encoded by the TCRA, TCRB, TCRG, and TCRD loci, respectively. The genes encoding the TCR proteins are composed of V and C exons, with the V exon being made up of small V, D, and/or J gene segments that are assembled at the DNA level by V(D)J recombination. The TCRA and TCRG loci contain V and J gene segments, but no D segments. TCRD is nested within the TCRA locus and contains its own Vδ, Dδ, and Jδ gene segments and Cδ exon, but also shares the use of some Vα gene segments. The additional D-D joints present in these exons dramatically enhance the junctional diversity found in TCRδ chains.