PDB 1YJD deposited: 2005-01-14 modified: 2011-07-13
Title Crystal structure of human CD28 in complex with the Fab fragment of a mitogenic antibody (5.11A1)
Authors Davis, S.J., Esnouf, R.M., Evans, E.J., Fennelly, J.A., Gilbert, R.J.C., Hanke, T., Hunig, T., James, J.R., Manso-Sancho, R., Sorensen, P., Stuart, D.I., Vowles, C., Walse, B., Yu, C.
Structure factors resolution 2.7 rfactor 0.239 rfree 0.282
DPI 1.05 theoretical min: 0.48

Naive T cell activation requires signaling by the T cell receptor and by nonclonotypic cell surface receptors. The most important costimulatory protein is the monovalent homodimer CD28, which interacts with CD80 and CD86 expressed on antigen-presenting cells. Here we present the crystal structure of a soluble form of CD28 in complex with the Fab fragment of a mitogenic antibody. Structural comparisons redefine the evolutionary relationships of CD28-related proteins, antigen receptors and adhesion molecules and account for the distinct ligand-binding and stoichiometric properties of CD28 and the related, inhibitory homodimer CTLA-4. Cryo-electron microscopy-based comparisons of complexes of CD28 with mitogenic and nonmitogenic antibodies place new constraints on models of antibody-induced receptor triggering. This work completes the initial structural characterization of the CD28-CTLA-4-CD80-CD86 signaling system.

Nat.Immunol. 2005 Mar; 6(3):271-279 doi:10.1038/ni1170

Cross References
Database source Identifier Description
PubMed 15696168
Biomolecule Structure Assembly Serial Assembly Type Conformational State Chains Ligands Atoms
1YJD/1 1YJD 1 hexamer 0 6 6 8202