Structure and dimerization of a soluble form of B7-1.
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Ikemizu S, Gilbert RJ, Fennelly JA, Collins AV, Harlos K, Jones EY, Stuart DI, Davis SJ
Structure and dimerization of a soluble form of B7-1.
Immunity. 2000 Jan;12(1):51-60.
- PubMed ID
- 10661405 [ View in 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.