VEGF-R1/Flt-1 His Tag Protein, Human

There are three evolutionarily related VEGF receptors in humans: VEGFR1 (FLT1), VEGFR2 (KDR/FLK1), and VEGFR3 (FLT4). They all comprise an extracellular, ligand-binding domain composed of seven immunoglobulin-like loops, a transmembrane domain, a juxtamembrane domain, a split intracellular TK domain, and a C-terminal tail; all three have different ligand-binding properties and biological functions. Expression of VEGFR1 depends on the microenvironment, is differentially regulated under hypoxic and inflammatory conditions, and it has been detected in retinal and choroidal endothelial cells, pericytes, retinal and choroidal mononuclear phagocytes (including microglia), Müller cells, photoreceptor cells, and the retinal pigment epithelium. VEGF signals primarily through the receptor tyrosine kinases VEGF receptor 1 (VEGF-R1, Flt-1) and 2 (VEGF-R2, Flk-1/KDR). VEGF-A binds VEGF receptors 1 and 2 (VEGFR1/2), whereas VEGF-B and PlGF only bind VEGFR1. In neo-vascularization, it is known that VEGF-R1 and VEGF-R2 (vascular endothelial growth factor receptors) act as receptors for VEGF-A (vascular endothelial growth factor). Placenta growth factor, a selective agonist of the VEGF-R1 receptor, induced phosphorylation of focal adhesion kinase (FAK) and extracellular signal regulated kinase 1/2 (ERK1/2).