Anti-HER3 antibody is specifically designed for immunoprecipitation and can be used for immunoblotting in conjunction with a detection antibody like anti-phosphotyrosine. Reactivity in other assays is likely, but has not been determined. Recognition of HER3 is independent of the phosphorylation status of the molecule. Human prostate cell lines (LNCap) or human breast cell line (MDA-453) are typically used as positive control sources. For immunoprecipitation use approximately 5 µL of the antibody. The immunoprecipitation mix contained the antibody, 25 µL of Protein A-agarose beads and 1.0 ml of lysate (lysate contains approximately 1.0 mg of total protein). This mixture is rotated overnight at 4°C and then washed 3 times with lysis buffer (used to prepare the lysate). The resulting bead complex is dissolved in 20-30 µL of 3X SDS-PAGE sample buffer and approximately 15 µL is loaded per lane on an 8% polyacrylamide gel. The combination of immunoprecipitation and immunoblotting was performing using the anti-HER3 antibody for immunoprecipitation followed by immunoblot detection using an anti-phosphotyrosine antibody. The complex is then reacted with HRP Goat-anti-Rabbit IgG and ECL for detection and shows a single HER3 band at 180kDa. Researchers should determine optimal titers for other applications.