TCRαβ Chains Associate with the Plasma Membrane Independently of CD3 and TCRζ Chains in Murine Primary T Cells

Abstract

AbstractThe TCR is a multisubunit complex composed of the clonotypic α/β disulfide-linked heterodimer and noncovalently linked invariant CD3γε and CD3δε and TCRζ chains. Recent studies demonstrate that the surface expression of CD3 components can occur independently of the clonotypic TCR complexes in both thymocytes and splenic T cells. In this study, we report that free noncovalently associated TCRαβ heterodimers that exist independently of CD3 and TCRζ chains are expressed on the cell surface of immature thymocytes and peripheral T cells, but not of T cell lines and T cell hybridomas. This suggests that the regulation of surface expression of TCRαβ heterodimers differs between primary T cells and T cell lines or T cell hybridomas. The isolation and biochemical characterization of surface clonotype-independent CD3 complexes and free membrane-associated TCRαβ complexes may provide a structural basis for the quantitative difference in amount of T cell proliferation stimulated by anti-CD3ε and anti-TCRβ.