The T cell receptor (TCR) is a heterodimeric molecule expressed on the surface of T lymphocytes, responsible for recognizing antigens presented by MHC molecules. In ~95% of T cells, the TCR consists of an α (alpha) and β (beta) chain (αβ TCR), while in ~5% of T cells, it is composed of γ (gamma) and δ (delta) chains (γδ TCR). TCR β is a member of the immunoglobulin superfamily and a component of the CD3/TCR complex, which includes CD3 subunits essential for signal transduction. This complex mediates antigen recognition, signal transduction, and subsequent T cell activation.
