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REACTIVITY SENSITIVITY MW (kDa) SOURCE
H Endogenous 185 Rabbit

Western blot analysis of extracts from T47-D cells, untreated (-) or treated (+) with NRG (Neuregulin) ligand (100 ng/ml, 5 min), using Phospho-HER3/ErbB3 (Tyr1328) Antibody (upper) or HER3/ErbB3 (1B2E) Rabbit mAb #4754 (lower).

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Product Usage Information

Application Dilutions
Western Blotting 1:1000
Immunoprecipitation 1:50

Storage: Supplied in 10 mM sodium HEPES (pH 7.5), 150 mM NaCl, 100 µg/ml BSA and 50% glycerol. Store at –20°C. Do not aliquot the antibody.

Specificity / Sensitivity

Phospho-HER3/ErbB3 (Tyr1328) Antibody recognizes endogenous levels of HER3/ErbB3 protein only when phosphorylated at Tyr1328. This antibody may cross-react with other overexpressed phosphotyrosine proteins.


Species Reactivity: Human
Species predicted to react based on 100% sequence homology: Mouse, Rat, Monkey

Source / Purification

Polyclonal antibodies are produced by immunizing animals with a synthetic phosphopeptide corresponding to residues surrounding Tyr1328 of human HER3/ErbB3 protein. Antibodies are purified by protein A and peptide affinity chromatography.

HER3/ErbB3 is a member of the ErbB receptor protein tyrosine kinase family, but it lacks tyrosine kinase activity. Tyrosine phosphorylation of ErbB3 depends on its association with other ErbB tyrosine kinases. Upon ligand binding, heterodimers form between ErbB3 and other ErbB proteins, and ErbB3 is phosphorylated on tyrosine residues by the activated ErbB kinase (1,2). There are at least 9 potential tyrosine phosphorylation sites in the carboxy-terminal tail of ErbB3. These sites serve as consensus binding sites for signal transducing proteins, including Src family members, Grb2, and the p85 subunit of PI3 kinase, which mediate ErbB downstream signaling (3). Both Tyr1222 and Tyr1289 of ErbB3 reside within a YXXM motif and participate in signaling to PI3K (4).

Investigators have found that ErbB3 is highly expressed in many cancer cells (5) and activation of the ErbB3/PI3K pathway is correlated with malignant phenotypes of adenocarcinomas (6). Research studies have demonstrated that in tumor development, ErbB3 may function as an oncogenic unit together with other ErbB members (e.g. ErbB2 requires ErbB3 to drive breast tumor cell proliferation) (7). Thus, investigators view inhibiting interaction between ErbB3 and ErbB tyrosine kinases as a novel strategy for anti-tumor therapy.


Phosphorylation of Tyr1328 on ErbB3 was identified at Cell Signaling Technology (CST) using PhosphoScan®, a CST™ LC-MS/MS platform for phosphorylation site discovery (8).


1.  Yarden, Y. and Sliwkowski, M.X. (2001) Nature Rev. Mol. Cell. Biol. 2, 127-137.

2.  Guy, P.M. et al. (1994) Proc. Natl. Acad. Sci. USA 91, 8132-8136.

3.  Songyang, Z. et al. (1993) Cell 72, 767-778.

4.  Kim, H.H. et al. (1994) J. Biol. Chem. 269, 24747-24755.

5.  Sithanandam, G. et al. (2003) Carcinogenesis 24, 1581-1592.

6.  Kobayashi, M. et al. (2003) Oncogene 22, 1294-1301.

7.  Holbro, T. et al. (2003) Proc. Natl. Acad. Sci. USA 100, 8933-8938.

8.  Rush, J. et al. (2005) Nat Biotechnol 23, 94-101.


Entrez-Gene Id 2065
Swiss-Prot Acc. P21860


For Research Use Only. Not For Use In Diagnostic Procedures.
Cell Signaling Technology® is a trademark of Cell Signaling Technology, Inc.