Purification, crystallization and preliminary characterization of an Eph-B2/ephrin-B2 complex

Eph receptors and their ephrin ligands are involved in various aspects of cell-cell communication during development, including those of the axon pathfinding processes in the nervous system and cell-cell interactions of the vascular endothelial cells. The recognition and binding properties of the ligand-binding domain of EphB2 receptor and the extracellular domain of ephrin-B2 have been studied and two different cocrystals of their complex have been generated. One crystal form has space group C2, diffracts to 3.5 Angstrom and has unit-cell parameters a = 128, b = 88, c = 79 Angstrom, beta = 112degrees. The other crystal form grows in space group P1, has unit-cell parameters a = 78, b = 78, c = 78 Angstrom, alpha = 69, beta = 75, gamma = 69degrees and diffracts to 2.7 Angstrom. Structure-determination experiments using the latter form are in progress. The structure of the complex will elucidate the chemical nature of the interactions between Eph receptors and ephrins, which would create the possibility of using them as targets for structure-based anticancer-drug development.