Recombinant Human HER2/ErbB2 Protein (C-His)

Measured by functional ELISA. Immobilized recombinant human HER2 ECD binds trastuzumab and pertuzumab (domains IV and II, respectively) with EC50 values in the range of 10–50 ng/mL.

HER2 (human epidermal growth factor receptor 2, ErbB2, CD340) is a receptor tyrosine kinase of the EGFR/ErbB family and one of the most clinically validated tumor-associated antigens. Unlike its relatives, HER2 has no known soluble ligand; it functions as the preferred heterodimerization partner for the other ErbB receptors and thereby potently amplifies MAPK and PI3K signaling. HER2 amplification or overexpression — present in roughly 15–20% of breast cancers and a subset of gastric and gastroesophageal cancers — defines a treatable molecular subtype addressed by trastuzumab, pertuzumab, the antibody–drug conjugates T-DM1 and trastuzumab deruxtecan, and small-molecule TKIs. The full extracellular domain presented here spans all four subdomains (I–IV), enabling epitope-level characterization of therapeutic and biosimilar antibodies, receptor-shedding studies, and the development of HER2-directed diagnostics and bispecifics.