Superantigens

thumb|right|Staphylococcal Enterotoxin B|SEB, a typical bacterial superantigen (PDB:3SEB). The β-grasp domain is shown in red, the β-barrel in green, the "[[disulfide loop" in yellow.]] thumb|right|SEC3 (yellow) complexed with an MHC class II molecule (green & cyan). The SAgs binds adjacent to the antigen presentation cleft (purple) in the MHC-II. thumb|Schematic representation of MHC class II. thumb|The T-cell receptor complex with TCR-α and TCR-β chains, CD3 and ζ-chain accessory molecules.