Peptide VIS

T-cell receptors (TCRs) made up of α- and β-chains have a very large number of ligands, including self- and foreign peptides, superantigens, lipids, small organic haptens, and metal ions. These ligands usually react with TCRs when they are bound to major histocompatibility complex (MHC) proteins. TCRs usually bind MHC/peptide combinations in similar orientations such that the TCR is aligned diagonally across the MHC/peptide, with the Vβ region of the TCR placed over the α1 α-helix of the MHCI heavy chain or of the MHCII α-chain and the Vα region placed over the α2 α-helix of the MHCI heavy chain or the β1 α-helix of the MHCII β-chain.