T-cell receptor

The T cell system evolved to recognize peptide/ MHC (pepMHC) ligands, thereby triggering a response to "foreign" antigens. Aberrant expression of a protein elicits T cells activation upon binding of the heterodimeric αβ T cell receptor (TCR) to the peptide/ MHC ligand. TCR docks onto the pepMHC in a conserved diagonal orientation, and that the specificity for the peptide is conferred largely by interactions between the complementarity-determining region (CDR) three loops of each TCR chain (CDR3a, CDR3b) and the peptide. The other four CDR loops (CDR1a, CDR2a, CDR1b, CDR2b) are generally more involved in MHC contact, although CDR1 loops can in some cases contact peptide
During T cell development, the random splicing of TCR gene segments generates multiple TCR segments: Vα, Jα, Vβ, Dβ, and Jβ, within the TCR locus. Antigen specificity is imparted through the hypervariable complementarity determining regions (CDRs) encoded within the V gene segments. TCR diversity is associated with many kinds of diseases, such as cancer, autoimmunity disease and HIV infection. TCR diversity is very important for human health; some scholars believe that αβ T cell receptors can be predictors of health and disease.