Cross-linking of human T cell receptor proteins: association between the T cell idiotype β subunit and the T3 glycoprotein heavy subunit

Abstract

Bifunctional cross-linking reagents DSP, DSS, and BSOCOES were used to cross-link 125I-surface-labeled viable T lymphocytes. The cross-linked cells were solubilized in Nonidet-P40, immunoprecipitated with anti-Ti (monoclonal antibody T40/25) or anti-T3 (monoclonal antibodies UCHT-1 or OKT3), and analyzed by SDS-PAGE. With all three cross-linkers, the intact cross-linked products obtained with monoclonal antibody T40/25 from HPB-ALL cells were 20–30 kd heavier than the Ti dimer (M r 80,000). When the DSP cross-linked product was isolated using either anti-Ti or anti-T3 monoclonal antibodies and then cleaved, bands having molecular weights identical with both the Ti and T3 subunits were obtained. The two-dimensional SDS-PAGE analysis (nonreducing followed by reducing conditions) of the DSS and BSOCOES cross-linked products revealed the specifically cross-linked bands to have M r 40,000 and M r 28,000. These data indicate that the Ti molecule and the T3 molecule are spatially associated on the cell surface and suggest the predominant association is between the Ti β subunit (M r 40,000) and the T3 heavy subunit (M r 28,000).