Cell Signaling Technology

Product Pathways - TGF-beta/Smad Signaling

Phospho-Smad3 (Ser423/425) (C25A9) Rabbit mAb #9520

Applications Reactivity Sensitivity MW (kDa) Isotype
W IP ChIP H M R (Mk) (X) (Z) (B) Endogenous 52 Rabbit IgG

Applications Key:  W=Western Blotting  IP=Immunoprecipitation  ChIP=Chromatin IP
Reactivity Key:  H=Human  M=Mouse  R=Rat  Mk=Monkey  X=Xenopus  Z=Zebrafish  B=Bovine
Species cross-reactivity is determined by western blot. Species enclosed in parentheses are predicted to react based on 100% sequence homology.

Protocols

Specificity / Sensitivity

Phospho-Smad3 (Ser423/425) (C25A9) Rabbit mAb detects endogenous levels of Smad3 when phosphorylated at Ser423/425. This antibody does not cross-react with other family members.

Source / Purification

Monoclonal antibody is produced by immunizing animals with a synthetic phosphopeptide corresponding to residues surrounding Ser423/425 of Smad3.

Western Blotting

Western Blotting

Western blot analysis of extracts from HT-1080 cells, untreated or treated with TGF-β1, TGFR inhibitor SB-431542 or BMP-2, using Phospho-Smad3 (Ser423/425) (C25A9) Rabbit mAb (top) or total Smad3 (C67H9) Rabbit mAb #9523 (bottom).

Chromatin IP

Chromatin IP

Chromatin immunoprecipitations were performed with cross-linked chromatin from 4 x 106 HaCaT cells treated with Human TGF-β3 #3706 (7 ng/ml) for 1 h and either 5 μl of Phospho-Smad3 (Ser423/425) (C25A9) Rabbit mAb or 2 μl of Normal Rabbit IgG #2729 using SimpleChIP® Enzymatic Chromatin IP Kit (Magnetic Beads) #9003. The enriched DNA was quantified by real-time PCR using SimpleChIP® Human CDKN1A Intron 1 Primers #4669, SimpleChIP® Human ID1 Promoter Primers #5139, human c-Myc intron 1 primers, and SimpleChIP® Human α Satellite Repeat Primers #4486. The amount of immunoprecipitated DNA in each sample is represented as signal relative to the total amount of input chromatin, which is equivalent to one.

Background

Members of the Smad family of signal transduction molecules are components of a critical intracellular pathway that transmit TGF-β signals from the cell surface into the nucleus. Three distinct classes of Smads have been defined: the receptor-regulated Smads (R-Smads), which include Smad1, 2, 3, 5, and 8; the common-mediator Smad (co-Smad), Smad4; and the antagonistic or inhibitory Smads (I-Smads), Smad6 and 7 (1-5). Activated type I receptors associate with specific R-Smads and phosphorylate them on a conserved carboxy terminal SSXS motif. The phosphorylated R-Smad dissociates from the receptor and forms a heteromeric complex with the co-Smad (Smad4), allowing translocation of the complex to the nucleus. Once in the nucleus, Smads can target a variety of DNA binding proteins to regulate transcriptional responses (6-8).

Following stimulation by TGF-β, Smad2 and Smad3 become phosphorylated at carboxyl terminal serine residues (Ser465 and 467 on Smad2; Ser423 and 425 on Smad3) by TGF-β Receptor I. Phosphorylated Smad 2/3 can complex with Smad4 and translocate to the nucleus to regulate gene expression (9-11).

  1. Heldin, C.H. et al. (1997) Nature 390, 465-471.
  2. Attisano, L. and Wrana, J.L. (1998) Curr. Opin. Cell Biol. 10, 188-194.
  3. Derynck, R. et al. (1998) Cell 95, 737-740.
  4. Massague, J. (1998) Annu. Rev. Biochem. 67, 753-791.
  5. Whitman, M. (1998) Genes Dev. 12, 2445-2462.
  6. Wu, G. et al. (2000) Science 287, 92-97.
  7. Attisano, L. and Wrana, J.L. (2002) Science 296, 1646-1647.
  8. Moustakas, A. et al. (2001) J. Cell Sci. 114, 4359-4369.
  9. Abdollah, S. et al. (1997) J. Biol. Chem. 272, 27678-27685.
  10. Souchelnytskyi, S. et al. (1997) J. Biol. Chem. 272, 28107-28115.
  11. Liu, X. et al. (1997) Proc. Natl. Acad. Sci. USA 94, 10669-10674.

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