Recombinant Human ErbB3

V-erb-b2 erythroblastic leukemia viral oncogene homolog 3 (avian), also known as ERBB3 is a member of the epidermal growth factor (EGF) receptor subfamily of receptor tyrosine kinases and is believed to be a receptor for an unknown ligand.¹ ErbB3 has a heregulin (HRG) or neuregulin binding domain but lacks intrinsic protein tyrosine kinase activity.² Therefore, it can bind to the ligand but not convey the signal into the cell through protein phosphorylation. However, it does form heterodimers with other EGF receptor family members which do have kinase activity.
Heterodimerization leads to the activation of pathways which lead to cell proliferation or differentiation. Amplification of ErbB3 and/or over-expression of its protein have been reported in numerous cancers, including prostate, bladder, and breast tumors.

The biological activity of Human ErbB3 was determined by its ability to inhibit the biological activity of human Neuregulin-1-b1 on MCF-7 cells. The expected ED₅₀ for this effect in the presence of 10 ng/ml rhNRG-1-b1 is 1.5-6.0 mg/ml.

Fc Fusion Protein

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Ser20

Lyophilized

The predicted molecular weight of Recombinant Human ErbB3 is Mr 96 kDa. However, the actual molecular weight as observed by migration on SDS-PAGE is Mr 130-140 kDa.

96

This recombinant protein was 0.2 µm filtered and lyophilized from modified Dulbecco’s phosphate buffered saline (1X PBS) pH 7.2 – 7.3 with no calcium, magnesium, or preservatives.

This lyophilized protein is stable for six to twelve months when stored desiccated at -20°C to -70°C. After aseptic reconstitution, this protein may be stored at 2°C to 8°C for one month or at -20°C to -70°C in a manual defrost freezer. Avoid Repeated Freeze Thaw Cycles. See Product Insert for exact lot specific storage instructions.

Next Day Ambient

1. Cerione, RA. et al. (1994) J Biol Chem. 269: 14303
2. Koland, JG. et al. (1998) Biochem J. 333: 757