PMID: 15696168

 

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Title : Crystal structure of a soluble CD28- Fab complex

Abstract :
  1. Naive T cell activation requires signaling by the T cell receptor and by nonclonotypic cell surface receptors
  2. The most important costimulatory protein is the monovalent homodimer CD28 , which interacts with CD80 and CD86 expressed on antigen-presenting cells
  3. Here we present the crystal structure of a soluble form of CD28 in complex with the Fab fragment of a mitogenic antibody
  4. 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
  5. Cryo-electron microscopy-based comparisons of complexes of CD28 with mitogenic and nonmitogenic antibodies place new constraints on models of antibody-induced receptor triggering
  6. This work completes the initial structural characterization of the CD28- CTLA-4- CD80- CD86 signaling system