TCR

TCR or T Cell Receptor is a protein complex found on the surface of T cells, a type of white blood cell that plays a crucial role in the immune system. The TCR is responsible for recognizing fragments of antigen as peptides bound to major histocompatibility complex (MHC) molecules.

Structure

The TCR is composed of two different protein chains (α and β chain). In 95% of T cells, the TCR consists of an alpha (α) chain and a beta (β) chain (encoded by TRA and TRB, respectively), whereas in 5% of T cells the TCR consists of gamma and delta (γ/δ) chains (encoded by TRG and TRD, respectively).

Function

The main function of the TCR is to recognize antigens bound to MHC molecules on the surface of antigen presenting cells. This recognition is crucial for the immune response, leading to the activation and proliferation of T cells, and their differentiation into effector and memory cells.

Clinical significance

Alterations in the TCR can lead to diseases such as autoimmune diseases, cancer, and infectious diseases. For example, in autoimmune diseases, the TCR may recognize self-antigens, leading to an immune response against the body's own cells.

See also

• Major histocompatibility complex
• Antigen presenting cell
• Autoimmune diseases
• Cancer
• Infectious diseases