Biophysical and structural studies of TCRs and ligands: implications for T cell signaling

The availability of soluble αβ TCRs and the individual chains has now made it possible to carry out structural studies of these molecules and analyze their molecular interactions with peptide-MHC ligands. Recent X-ray crystallographic structures of TCR α and β chains have finally established their structural similarity with the Ig molecules. Kinetic measurements of the interaction between TCRs and their ligands have provided strong evidence in favour of an affinity/avidity model for T cell activation in the periphery as well as during development in the thymus.