T Cell Receptor

The T cell receptor is a protein molecule located on the surface of T cells, whose function is to recognize antigens bound to major histocompatibility complex (MHC) molecules. The T cell receptors allow the T cell to recognize antigen presented in the context of major histocompatibility complex class I or class II molecules, which are expressed on infected cells or professional antigen-presenting cells.

A T cell receptor is a heterodimer which is composed of an alpha and beta chain in 95% of T cells, whereas 5% of T cells have TCRs consisting of gamma and delta chains. Engagement of the T cell receptor with antigen and major histocompatibility results in activation of its T lymphocyte through a series of biochemical events mediated by associated enzymes, co-receptors, specialized accessory molecules and activated or released transcription factors.