Anti-Smad4 Polyclonal Antibody for WB, IF/ICC, IHC-P, ELISA - Q13485

Core Product Specifications and Parameters

Biological Background: Smad4 Function and Localization

• SMAD4 is the common mediator (co-SMAD) of TGF-β superfamily signal transduction. It forms a heterotrimeric complex with receptor-regulated SMADs (e.g., SMAD2/3) in the nucleus, which is essential for TGF-β-mediated transcriptional regulation.
  Related references:
  PMID:25514493
• Acts as a transcriptional coactivator: SMAD4 facilitates DNA binding of the SMAD2/SMAD4/FAST-1 complex and provides an activation domain for SMAD1- or SMAD2-driven transcription. It also participates in the AP-1 transcription factor complex (SMAD3/SMAD4/JUN/FOS) to synergize TGF-β responses.
• Functions as a tumor suppressor; loss or inactivation of SMAD4 is a frequent event in pancreatic ductal adenocarcinoma, colorectal cancer, and other malignancies, underscoring its role in growth control.
• In muscle physiology, SMAD4 acts as a nodal switch: when recruited by myostatin (MSTN), it promotes atrophy through SMAD2/4 signaling; when released, it shifts to BMP-mediated hypertrophy via SMAD1/5/8 (by similarity).
• SMAD4 positively regulates PDPK1 kinase activity by promoting its dissociation from the inhibitory 14-3-3 protein YWHAQ.
• Localizes in both cytoplasm and nucleus; nuclear translocation is induced upon TGF-β or BMP stimulation, where it accumulates in transcriptionally active complexes.
• Contains N-terminal MH1 domain for DNA binding to SBEs (5’-GTCT/AGAC-3’) and C-terminal MH2 domain for receptor interaction, oligomerization, and transcriptional activation. The protein is subject to acetylation, phosphorylation, and ubiquitination.

Experimental Guidance and Technical Tips

• The immunogen corresponds to the C-terminal MH2 domain (aa 320–552), which is highly conserved across human, mouse, and rat, consistent with the reported cross-reactivity. For novel species, sequence alignment is recommended.
• For Western blotting (WB), a band at approximately 60 kDa is expected. Use appropriate loading controls and validate in TGF-β-treated versus untreated lysates to confirm specificity.
• For immunofluorescence/immunocytochemistry (IF/ICC) and immunohistochemistry (IHC-P), nuclear or cytoplasmic staining may be observed depending on signaling context. Include appropriate negative controls (e.g., knockout cell lines or blocking peptide) to verify signal specificity.
• For ELISA applications, optimize coating antigen and detection conditions. The antibody can be paired with monoclonal antibodies against different epitopes to develop sandwich ELISA systems for SMAD4 quantification.
• Given the antibody's polyclonal nature, lot-to-lot consistency should be verified in critical quantitative assays. Consider using recombinant antibody technology if reproducibility is a primary concern.

CamelBio: Your One-Stop Sourcing Bridge

CamelBio provides researchers and diagnostic manufacturers with reliable access to critical signaling pathway reagents like anti-Smad4 antibodies. From validated antibody pairs to bulk ancillary reagents, our portfolio supports the development of robust assays for TGF-β/BMP pathway analysis and cancer research. We also offer customized sourcing for rare targets, enabling seamless progression from concept to clinic.