Structural highlights
Function
[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.[1] [2]
Publication Abstract from PubMed
The EphB receptors have key roles in cell morphology, adhesion, migration and invasion, and their aberrant action has been linked with the development and progression of many different tumour types. Their conflicting expression patterns in cancer tissues, combined with their high sequence and structural identity, present interesting challenges to those seeking to develop selective therapeutic molecules targeting this large receptor family. Here, we present the first structure of the EphB1 tyrosine kinase domain determined by X-ray crystallography to 2.5A. Our comparative crystalisation analysis of the human EphB family kinases has also yielded new crystal forms of the human EphB2 and EphB4 catalytic domains. Unable to crystallize the wild-type EphB3 kinase domain, we used rational engineering (based on our new structures of EphB1, EphB2 and EphB4) to identify a single point mutation which facilitated its crystallization and structure determination to 2.2A. This mutation also improved the soluble recombinant yield of this kinase within Escherichia coli, and increased both its intrinsic stability and catalytic turnover, without affecting its ligand-binding profile. The partial ordering of the activation loop in the EphB3 structure alludes to a potential cis-phosphorylation mechanism for the EphB kinases. With the kinase domain structures of all four catalytically competent human EphB receptors now determined, a picture begins to emerge of possible opportunities to produce EphB isozyme-selective kinase inhibitors for mechanistic studies and therapeutic applications.
Completing the structural family portrait of the human EphB tyrosine kinase domains.,Overman RC, Debreczeni JE, Truman CM, McAlister MS, Attwood TK Protein Sci. 2014 Feb 15. doi: 10.1002/pro.2445. PMID:24677421[3]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ 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
- ↑ Overman RC, Debreczeni JE, Truman CM, McAlister MS, Attwood TK. Completing the structural family portrait of the human EphB tyrosine kinase domains. Protein Sci. 2014 Feb 15. doi: 10.1002/pro.2445. PMID:24677421 doi:http://dx.doi.org/10.1002/pro.2445
