Structure and dimerization of a soluble form of B7-1.
Ikemizu, S., Gilbert, R.J., Fennelly, J.A., Collins, A.V., Harlos, K., Jones, E.Y., Stuart, D.I., Davis, S.J.(2000) Immunity 12: 51-60
- PubMed: 10661405 
- DOI: https://doi.org/10.1016/s1074-7613(00)80158-2
- Primary Citation of Related Structures:  
1DR9 - PubMed Abstract: 
B7-1 (CD80) and B7-2 (CD86) are glycoproteins expressed on antigen-presenting cells. The binding of these molecules to the T cell homodimers CD28 and CTLA-4 (CD152) generates costimulatory and inhibitory signals in T cells, respectively. The crystal structure of the extracellular region of B7-1 (sB7-1), solved to 3 A resolution, consists of a novel combination of two Ig-like domains, one characteristic of adhesion molecules and the other previously seen only in antigen receptors. In the crystal lattice, sB7-1 unexpectedly forms parallel, 2-fold rotationally symmetric homodimers. Analytical ultracentrifugation reveals that sB7-1 also dimerizes in solution. The structural data suggest a mechanism whereby the avidity-enhanced binding of B7-1 and CTLA-4 homodimers, along with the relatively high affinity of these interactions, favors the formation of very stable inhibitory signaling complexes.
Organizational Affiliation: 
Division of Structural Biology, Wellcome Trust Centre for Human Genetics, The University of Oxford, United Kingdom.