Title : Crystal structure of a soluble
CD28-
Fab complex
Abstract :
- 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