Human epidermal growth factor receptor 2 (HER2), also known as ERBB2 and Neu, is a cell surface receptor and member of the EGF family of receptor tyrosine kinases that is encoded by ERBB2 in humans.1 It is a 185 kDa transmembrane receptor composed of an intracellular tyrosine kinase domain, a transmembrane lipophilic segment, and an extracellular domain, that is expressed at low levels in various epithelial tissues, as well as breast, lung, kidney, ovary, placenta, and the gastrointestinal tract.2 Unlike other EGF receptors, HER2 does not bind ligands or undergo a conformational change in its extracellular domain for activation. HER2 is activated upon heterodimerization with HER3 or HER4, which stabilizes ligand binding to HER3 and HER4, or homodimerization and enhances kinase-mediated activation of the MAPK and PI3K cellular signaling pathways.1,2 Truncated forms of HER2 with constitutive oncogenic activity can be generated by proteolytic cleavage of the extracellular domain, and serum levels of the extracellular domain are increased in patients with breast, ovarian, lung, and prostate cancers.2 ERBB2 is overexpressed in 12 to 15% of breast cancer tumors and is associated with accelerated growth rate, increased rate of recurrence, and poor overall survival.2 Various mutations in ERBB2, with or without gene amplification, have been found in prostate, colon, bladder, breast, lung, and colorectal tumors, as well as metastatic cutaneous squamous small cell carcinomas.3,4 Cayman’s HER2/ERBB2 Extracellular Domain (human, recombinant) protein can be used for ELISA, Western blot, and cell-based assay applications. This protein is a disulfide-linked homodimer. The reduced monomer, comprised of HER2/ERBB2 (amino acids 23-652) fused to human IgG1 Fc at its C-terminus, consists of 868 amino acids and has a calculated molecular weight of 96.1 kDa. As a result of glycosylation, the monomer migrates at approximately 130-140 kDa by SDS-PAGE under reducing conditions.WARNING This product is not for human or veterinary use.
