NCIt synonyms : MHC Receptor; Major Histocompatibility Complex Receptor; TCR;
NCIt definition : Heterodimeric antigen receptors present on the surface of T-cells. Two T-cell antigen
receptors have been identified, consisting of heterodimeric 40-55 kD Ig-like alpha/beta
or gamma/delta integral membrane glycoproteins. Genes for TCR alpha, beta, gamma,
and delta subunits are assembled during T-cell development by somatic rearrangement
of germline gene segments, resembling B-cell Ig genes in their mechanisms of diversity
generation and activation of expression. Alpha/beta heterodimers are found on helper
and cytotoxic T-cells and are specific for antigenic peptides presented by MHC gene
products. T-cells expressing gamma/delta heterodimers directly recognize proteins
and non-proteinacious phospho-ligands. T-cell receptors are non-covalently associated
with CD3, forming the TCR-CD3 complex. TCRs activate MAPKs and JNK1 through the CD3
antigens, the adaptor protein LAT, and tyrosine kinases LCK and ZAP70. (from OMIM
and NCI);