AffinityImmuno Products

Introduction

ERBB3 (HER3) encodes a receptor tyrosine kinase belonging to the EGFR/ErbB family, but its intracellular domain lacks catalytic kinase activity, so it functions as a signaling partner rather than an autonomous enzyme. It carries a binding site for the ligand neuregulin-1, and engagement by this or related ligands drives pairing with catalytically active family members such as EGFR or HER2, triggering downstream proliferation and differentiation cascades including PI3K/AKT signaling. Amplification or overexpression of ERBB3 has been documented across a range of solid tumors, including breast, prostate, bladder, and gastrointestinal malignancies, making it a target of interest in oncology research. Separately, rare inherited loss-of-function variants in the same gene have been linked to congenital neuromuscular contracture and visceral neuropathy syndromes, underscoring its additional developmental role outside of cancer biology.

HER3 has become a validated oncology drug target through patritumab deruxtecan (HER3-DXd), an antibody-drug conjugate studied extensively in EGFR-mutated non-small cell lung cancer, adding a fast-moving translational-oncology use case to HER3’s established role as an amplified/overexpressed signaling partner across breast, prostate, bladder, and GI tumors.

Principle of the Assay

This kit utilizes a sandwich enzyme immunoassay format in which the microtiter plate wells are pre-coated with a capture antibody specific to Human HER3/ERBB3. During the assay, standards or samples are introduced into the appropriate wells alongside a biotin-conjugated detection antibody that also targets Human HER3/ERBB3. Avidin conjugated to horseradish peroxidase (HRP) is then added to each well and allowed to incubate. Upon addition of TMB substrate solution, a colorimetric signal develops exclusively in wells where Human HER3/ERBB3, the biotin-conjugated detection antibody, and the avidin-HRP conjugate are all present. The enzymatic reaction is halted by addition of a sulphuric acid stop solution, and the resulting color change is measured spectrophotometrically at 450 nm (± 10 nm). HER3/ERBB3 concentrations in unknown samples are subsequently determined by referencing sample optical density values against a standard curve.