Nrp1, also known as Neuropilin 1, is a transmembrane glycoprotein that acts as a co-receptor for a number of extracellular ligands including class III/IV semaphorins, certain isoforms of vascular endothelial growth factor and transforming growth factor beta. It binds vascular endothelial growth factor (VEGF)-A and is thought to act as a coreceptor for kinase insert domain-containing receptor (KDR) by associating with KDR and enhancing VEGF signaling. It is a marker of regulatory T cells. Recombinant mouse Nrp1, fused to His-tag at C-terminus, was expressed in insect cell and purified by using conventional chromatography techniques.