[EPHB4_HUMAN] Receptor tyrosine kinase which binds promiscuously transmembrane ephrin-B family ligands residing on adjacent cells, leading to contact-dependent bidirectional signaling into neighboring cells. The signaling pathway downstream of the receptor is referred to as forward signaling while the signaling pathway downstream of the ephrin ligand is referred to as reverse signaling. Together with its cognate ligand/functional ligand EFNB2 plays a central role in heart morphogenesis and angiogenesis through regulation of cell adhesion and cell migration. EPHB4-mediated forward signaling controls cellular repulsion and segregation form EFNB2-expressing cells. Plays also a role in postnatal blood vessel remodeling, morphogenesis and permeability and is thus important in the context of tumor angiogenesis.
The Eph receptor tyrosine kinases and their ligands, the ephrins, regulate numerous biological processes in developing and adult tissues and have been implicated in cancer progression and in pathological forms of angiogenesis. We report the crystal structure of the EphB4 receptor in complex with a highly specific antagonistic peptide at a resolution of 1.65 angstroms. The peptide is situated in a hydrophobic cleft of EphB4 corresponding to the cleft in EphB2 occupied by the ephrin-B2 G-H loop, consistent with its antagonistic properties. Structural analysis identifies several residues within the EphB4 binding cleft that likely determine the ligand specificity of this receptor, while isothermal titration calorimetry experiments with truncated forms of the peptide define the amino acid residues of the peptide that are critical for receptor binding. These studies reveal structural features that will aid drug discovery initiatives to develop EphB4 antagonists for therapeutic applications.
Structure and thermodynamic characterization of the EphB4/Ephrin-B2 antagonist peptide complex reveals the determinants for receptor specificity.,Chrencik JE, Brooun A, Recht MI, Kraus ML, Koolpe M, Kolatkar AR, Bruce RH, Martiny-Baron G, Widmer H, Pasquale EB, Kuhn P Structure. 2006 Feb;14(2):321-30. PMID:16472751
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↑ Fuller T, Korff T, Kilian A, Dandekar G, Augustin HG. Forward EphB4 signaling in endothelial cells controls cellular repulsion and segregation from ephrinB2 positive cells. J Cell Sci. 2003 Jun 15;116(Pt 12):2461-70. Epub 2003 May 6. PMID:12734395 doi:10.1242/jcs.00426
↑ Erber R, Eichelsbacher U, Powajbo V, Korn T, Djonov V, Lin J, Hammes HP, Grobholz R, Ullrich A, Vajkoczy P. EphB4 controls blood vascular morphogenesis during postnatal angiogenesis. EMBO J. 2006 Feb 8;25(3):628-41. Epub 2006 Jan 19. PMID:16424904 doi:10.1038/sj.emboj.7600949
↑ Chrencik JE, Brooun A, Recht MI, Kraus ML, Koolpe M, Kolatkar AR, Bruce RH, Martiny-Baron G, Widmer H, Pasquale EB, Kuhn P. Structure and thermodynamic characterization of the EphB4/Ephrin-B2 antagonist peptide complex reveals the determinants for receptor specificity. Structure. 2006 Feb;14(2):321-30. PMID:16472751 doi:10.1016/j.str.2005.11.011