Issues

Molecular model for recognition of a lipid antigen–CD1 complex by a T cell receptor. The hydrophobic CD1 antigen-binding groove is visualized from the side between the α1 and α2 helices. The mycolic acid–specific, CD1b-restricted DN1 TCR Vα and Vβ complementarity determining loops (blue) are modeled over human CD1b (red). Lipid antigen acyl chain tails are thought to bind in the CD1 hydrophobic groove, whereas the polar heads of amphipathic lipid and glycolipid antigens are predicted to be exposed at the solvent interface with the CD1 helices. The side chains of residues R97 and R98 in the DN1 TCR-β CDR3 region (yellow) project into the hydrophobic cleft where the polar moieties of the lipid antigen are hypothesized to be located. See related article in this issue by Grant et al., pp. 195–205.