Molecular characterization of the murine T cell antigen receptor and associated structures

Previous studies have demonstrated that the T cell antigen-specific receptor is a disulfide-linked heterodimer with subunits of 40-48 kilodaltons. We have produced a series of antiserums and monoclonal antibodies to epitopes carried by the molecule, including clonotypic epitopes specific to individual T lymphomas as well as epitopes shared by different T cell lines. Using these reagents we have isolated the heterodimers from a variety of T cells for comparison of primary structure via two-dimensional peptide mapping. The results indicate that 1) the peptide maps of the α and β subunits are extremely different, indicating that the subunits are encoded by different genes, and 2) both subunits contain constant as well as variable peptides. To determine whether the murine T cell receptor is associated with other cell surface structures, C6VL lymphoma cells were radioiodinated, cross-linked with the cleavable reagent dimethyl-3,3'-dithiobispropionimidate, solubilized, and subjected to immunoprecipitation with the clonotypic antibody 124-40, and the precipitates were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Cross-linked samples, but no sham-treated precipitates, contained structures similar to the human Leu-4/T3 structure in addition to the receptor subunits. These results indicate that similar structures may be associated with the receptor in the human and the mouse.