Receptor tyrosine-protein kinase (ErbB3), also known as human epidermal growth factor receptor 3 (HER3), is a membrane bound protein that is encoded by the ERBB3 gene. ErbB3 possesses a neuregulin binding domain but lacks an active kinase domain, and as a result, it can bind this ligand but cannot phosphorylate proteins to send the signal to the cell. Together with other kinase-active members of the EGF receptor family, ErbB3 forms heterodimers. Pathways that cause cell proliferation or differentiation are activated by heterodimerization. In human breast cancer and other tumors such as prostate and bladder, ErbB3 overexpression is a sign of poor patient prognosis.

The AlphaLISA SureFire Ultra Multiplex Human Phospho-ErbB3 (Tyr1289)/Total ErbB3 Detection Kit is used to measure phosphorylated ErbB3 (Tyr1289) and total levels of ErbB3 in cellular lysates in a multiplexing Alpha no-wash assay. No specially engineered cell lines are required. The 615 nm (Eu) signal corresponds to the phosphorylated ErbB3, and the 545 nm (Tb) signal corresponds to the total ErbB3 analysis. This kit has been formulated to provide superior signal:background assay windows and to perform without interference in the presence of extraneous antibodies, making it amenable to the study of therapeutic and blocking antibodies.

• No-wash steps, no separation steps
• Multiplexing assay
• Sensitive detection
• No interference from exogenous antibodies
• Results in less than 3 hours

In this assay, the Alpha 615 Acceptor bead is coated with the CaptSure™ antibody, which binds the CaptSure-tagged anti-phospho target antibody. The Alpha 545 Acceptor bead is coated with the CaptSure2™ agent, which binds the CaptSure2 tagged anti-total target protein antibody. The Alpha Donor bead binds the biotinylated anti-total target protein antibody.