Description
Introduction: Vascular endothelial cell growth factor (VEGF), also known as vascular permeability factor, is an endothelial cell mitogen, which stimulates angiogenesis by binding to specific receptors (VEGFRs) on the surface of vascular endothelial cells. The VEGF ligand/receptor signaling system plays a key role in vascular development and regulation of vascular permeability. All the three receptors for VEGF, VEGFR1~3, belong to CSF-1/PDGF receptor subfamily of receptor tyrosine kinase superfamily (RTKs), and contains seven Ig-like C2-type domains in the ECD, as well as a intracellular protein kinase domain. VEGFR2, also called as KDR or Flk-1, is identified as the receptor for VEGF and VEGFC and an early marker for endothelial cell progenitors, whose expression is restricted to endothelial cells in vivo. The adaptor protein SHB has been shown to interact with VEGFR2 in receptor tyrosine kinase signaling. In addition, VEGFR2 is able to interact with HIV-1 extracellular Tat protein upon VEGF activation, and seems to enhance angiogenesis in Kaposi's sarcoma lesions.
Principle of the Assay: The microtiter plate provided in this kit has been pre-coated with an antibody specific to VEGFR-2/Flk-1. Standards or samples are then added to the appropriate microtiter plate wells with a biotin-conjugated polyclonal antibody preparation specific for VEGFR-2/Flk-1 and Avidin conjugated to Horseradish Peroxidase (HRP) is added to each microplate well and incubated. Then a TMB (3,3',5,5' tetramethyl-benzidine) substrate solution is added to each well. Only those wells that contain VEGFR-2/Flk-1, biotin-conjugated antibody and enzyme-conjugated Avidin will exhibit a change in color. The enzyme-substrate reaction is terminated by the addition of a sulphuric acid solution and the color change is measured spectrophotometrically at a wavelength of 450 nm +/- 2 nm. The concentration of VEGFR-2/Flk-1 in the samples is then determined by comparing the O.D. of the samples to the standard curve