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 the peptide maps of the alpha and beta subunits are extremely different, indicating that the subunits are encoded by different genes, and 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 not 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.