3v6b

Publication Abstract from PubMed

Vascular Endothelial Growth Factors (VEGFs) activate three receptor tyrosine kinases, VEGFR-1-3, promoting angiogenic and lymphangiogenic signaling. The extracellular receptor domain (ECD) consists of seven immunoglobulin-homology domains; domains 2 and 3 (D23) represent the ligand binding domain, while the function of D4-7 is unclear. Ligand binding promotes receptor dimerization and instigates transmembrane signaling and receptor kinase activation. Isothermal titration calorimetry showed that the Gibbs free energy of VEGF-A, -C or -E binding to D23 or the full length ECD is dominated by favorable entropic contribution with enthalpic penalty. The free energy of VEGF binding to the ECD is 1.0-1.7 kcal/mol less favorable than for binding to D23. A model of the VEGF-E/VEGFR-2 ECD complex derived from small angle scattering data provided evidence for homotypic interactions in D4-7. We also solved the crystal structures of complexes between VEGF-A or -E with D23 which revealed comparable binding surfaces and similar interactions between the ligands and the receptor, but showed variation in D23 twist angles. The energetically unfavorable homotypic interactions in D4-7 may be required for re-orientation of receptor monomers. This mechanism might prevent ligand-independent activation of VEGFR-2 to evade the deleterious consequences for blood and lymph vessel homeostasis arising from inappropriate receptor activation.

Thermodynamic and structural description of allosterically regulated VEGF receptor 2 dimerization.,Brozzo MS, Bjelic S, Kisko K, Schleier T, Leppanen VM, Alitalo K, Winkler FK, Ballmer-Hofer K Blood. 2011 Dec 29. PMID:22207738^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.