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PhosphoSitePlus® Resource

  • Additional protein information
  • Analytical tools


Western Blotting

Western Blot analysis of extracts from serum starved HeLa cells, untreated or IFN-alpha-treated (100 ng/ml for 5 minutes), using a variety of Phospho-Stat3 and Stat 3 antibodies. The upper panels show the antibody pre-incubated with the blocking peptide while the lower panels have no blocking peptide added.

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Immunohistochemistry (Paraffin)

Immunohistochemical analysis of paraffin-embedded human colon carcinoma, using Phospho-Stat3 (Tyr705) (D3A7) Rabbit mAb #9145 in the presence of control peptide (left) or Phospho-Stat3 (Tyr705) Blocking Peptide (right).

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Product Description

This peptide is used to block Phospho-Stat3 (Tyr705) (D3A7) rabbit mAb #9145, Phospho-Stat3 (Tyr705) Antibody #9131, and Phospho-Stat3 (Tyr705) (3E2) mouse mAb #9138 reactivity.

Quality Control

The quality of the peptide was evaluated by reversed-phase HPLC and by mass spectrometry. The peptide blocks Phospho-Stat3 (Tyr705) (DA37) Rabbit mAb # 9145 by immunohistochemistry and western blotting and Phospho-Stat3 (Tyr705) Antibody # 9131 and Phospho-Stat3 (Tyr705) (3E2) Mouse mAb # 9138 signal by western blotting.

Product Usage Information

Use as a blocking reagent to evaluate the specificity of antibody reactivity in western immunoblotting and immunohistochemistry protocols. For immunohistochemistry, add twice the volume of peptide as volume of antibody used in 100 μl total volume. Incubate for a minimum of 30 minutes prior to adding the entire volume to the slide. Recommended antibody dilutions can be found on the product data sheet.

For western immunoblotting, add 10 µl of antibody and 10 µl of blocking peptide to 10 ml of antibody dilution buffer, and incubate at room

temperature for 30 minutes before allowing to react with the blot.

Storage: Supplied in 20 mM potassium phosphate (pH 7.0), 50 mM NaCl, 0.1 mM EDTA, 1 mg/ml BSA, 5% glycerol and 1% DMSO. Store at –20°C.

The Stat3 transcription factor is an important signaling molecule for many cytokines and growth factor receptors (1) and is required for murine fetal development (2). Research studies have shown that Stat3 is constitutively activated in a number of human tumors (3,4) and possesses oncogenic potential (5) and anti-apoptotic activities (3). Stat3 is activated by phosphorylation at Tyr705, which induces dimerization, nuclear translocation, and DNA binding (6,7). Transcriptional activation seems to be regulated by phosphorylation at Ser727 through the MAPK or mTOR pathways (8,9). Stat3 isoform expression appears to reflect biological function as the relative expression levels of Stat3α (86 kDa) and Stat3β (79 kDa) depend on cell type, ligand exposure, or cell maturation stage (10). It is notable that Stat3β lacks the serine phosphorylation site within the carboxy-terminal transcriptional activation domain (8).

1.  Heim, M.H. (1999) J Recept Signal Transduct Res 19, 75-120.

2.  Takeda, K. et al. (1997) Proc Natl Acad Sci U S A 94, 3801-4.

3.  Catlett-Falcone, R. et al. (1999) Immunity 10, 105-15.

4.  Garcia, R. and Jove, R. (1998) J Biomed Sci 5, 79-85.

5.  Bromberg, J.F. et al. (1999) Cell 98, 295-303.

6.  Darnell, J.E. et al. (1994) Science 264, 1415-21.

7.  Ihle, J.N. (1995) Nature 377, 591-4.

8.  Wen, Z. et al. (1995) Cell 82, 241-50.

9.  Yokogami, K. et al. (2000) Curr Biol 10, 47-50.

10.  Biethahn, S. et al. (1999) Exp Hematol 27, 885-94.

Entrez-Gene Id 6774
Swiss-Prot Acc. P40763

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Phospho-Stat3 (Tyr705) Blocking Peptide