T-cell receptor
T-cell receptor
The T-cell receptor (pronounced: T-cell ree-sep-tor) is a complex of integral membrane proteins that participates in the activation of T-cells in response to an antigen.
Etymology
The term "T-cell receptor" is derived from the type of cell it is found on, the T-cell, and its function as a receptor for antigens. The "T" in T-cell stands for thymus, the organ in which these cells mature.
Function
The T-cell receptor (TCR) recognizes fragments of antigen as peptides bound to major histocompatibility complex (MHC) molecules. The binding between TCR and antigen peptides is of relatively low affinity and is degenerate: many TCRs recognize the same antigen peptide and many antigen peptides are recognized by the same TCR.
Structure
The TCR is composed of two different protein chains (that is, it is a heterodimer). In humans, 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). This ratio changes during ontogeny and in diseased states (such as leukemia). It also differs between species.
Related Terms
- Antigen: A substance that induces an immune response in the body, especially the production of antibodies.
- Major Histocompatibility Complex (MHC): A set of cell surface proteins essential for the acquired immune system to recognize foreign molecules in vertebrates.
- Thymus: A specialized primary lymphoid organ of the immune system where T cells mature.
- Leukemia: A group of cancers that usually begin in the bone marrow and result in high numbers of abnormal white blood cells.
External links
- Medical encyclopedia article on T-cell receptor
- Wikipedia's article - T-cell receptor
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