The<unk>  or<unk>  is a molecule found on the surface of T lymphocytes (or T cells) that is, in general, responsible for recognizing antigens bound to major histocompatibility complex (MHC) molecules.
It is a heterodimer consisting of an alpha and beta chain in 95% of T cells, whereas 5% of T cells have<unk> s consisting of gamma and delta chains.
Engagement of the<unk>  with antigen and MHC results in activation of its T lymphocyte through a series of biochemical events mediated by associated enzymes, co-receptors, and specialized accessory molecules.
T cell receptor
Pattern recognition receptor
Tumor necrosis factor receptor
Interleukin-8 receptor
Receptor 
Soluble CD40 ligand 
Cell adhesion molecule
STAT protein