Phosphorylation of the T cell antigen receptor: multiple signal transduction pathways

In our previous description of the murine T cell antigen receptor complex (Samelson et al., 1985a), we demonstrated that the clonotypic alpha-beta heterodimer is associated with four additional polypeptides. These include the 26 kd delta chain, the 25 kd epsilon chain, a 21 kd glycoprotein probably homologous with the human T3 gamma chain, and a 16 kd homodimer, the zeta chain. These polypeptides are co-immunoprecipitated from T cell clones and normal peripheral T cells with monoclonal antibodies that bind the alpha-beta heterodimer or with antisera that bind the delta chain (Samelson et al., 1986b) or the zeta chain (Weissman et al., 1986). All of these murine polypeptides have counterparts on human T cells. These results indicated that the T cell antigen receptor is a seven-chain complex.