Recombinant Human EGFR Fc Chimera Avi-tag Protein, CF

The EGFR subfamily of receptor tyrosine kinases comprises four members: EGFR (also known as HER-1, ErbB1, or ErbB), ErbB2 (Neu, HER-2), ErbB3 (HER-3), and ErbB4 (HER-4). All family members are type I transmembrane glycoproteins with an extracellular ligand binding domain containing two cysteine-rich domains separated by a spacer region and a cytoplasmic domain containing a membrane-proximal tyrosine kinase domain followed by multiple tyrosine autophosphorylation sites (1-4). Soluble receptors consisting of the extracellular ligand binding domain are generated by alternate splicing in human and mouse (5‑7). Within the mature ECD, human EGFR shares 88% aa sequence identity with mouse and rat EGFR. Human EGFR shares 43%-44% aa sequence identity with the ECD of human ErbB2, ErbB3, and ErbB4. EGFR binds a subset of the EGF family ligands, including EGF, amphiregulin, TGF-alpha, betacellulin, epiregulin, HB-EGF, and epigen (1, 2). Ligand binding induces EGFR homodimerization as well as heterodimerization with ErbB2, resulting in kinase activation, heterodimerization tyrosine phosphorylation and cell signaling (8‑12). EGFR can also be recruited to form heterodimers with the ligand‑activated ErbB3 or ErbB4. EGFR signaling regulates multiple biological functions including cell proliferation, differentiation, motility, and apoptosis (13, 14). EGFR is overexpressed in a wide variety of tumors and is the target of several anti-cancer drugs (15).