FAA3 Antibody

What is FAA3 and how does it relate to TGFBR2?

FAA3 (also known as HNPCC6) is one of several alternative names for the TGFBR2 gene (Transforming Growth Factor Beta Receptor II). FAA3 is consistently listed among the gene aliases for TGFBR2 across multiple antibody resources . The TGFBR2 protein (which FAA3 antibodies target) functions as a transmembrane serine/threonine kinase receptor that binds TGF-beta ligands, playing crucial roles in cellular signaling pathways related to growth, differentiation, and apoptosis . When researchers reference FAA3 antibody, they are specifically referring to antibodies targeting the protein encoded by the TGFBR2 gene.

What are the primary applications for FAA3/TGFBR2 antibodies in research?

FAA3/TGFBR2 antibodies are utilized across multiple experimental applications with varying degrees of validation. Based on comprehensive antibody validation data, the primary applications include:

• Western Blot (WB) - Consistently validated across multiple antibody products

• Immunohistochemistry (IHC) - Particularly effective with paraffin-embedded sections

• Immunofluorescence (IF) - Validated for cellular localization studies

• Enzyme-Linked Immunosorbent Assay (ELISA) - Used for quantitative detection

• Immunoprecipitation (IP) - Applied for protein complex isolation

The experimental utility varies by antibody source and preparation method, with most products being validated for multiple applications rather than a single technique .

What host organisms are used to generate FAA3/TGFBR2 antibodies?

The predominant host organism for FAA3/TGFBR2 antibody production is rabbit, with multiple commercial sources using rabbit-derived polyclonal antibodies . This consistent pattern suggests rabbit immune systems generate effective antibody responses against TGFBR2 epitopes. The antibodies are typically purified through affinity chromatography methods, including peptide affinity purification and immunogen affinity purification . These purification strategies enhance specificity while reducing background noise in experimental applications.

How should samples be prepared for optimal detection with FAA3/TGFBR2 antibodies?

Sample preparation varies by application but follows these general principles:

For Western Blot:

• Use RIPA or NP-40 based lysis buffers containing protease inhibitors

• Include phosphatase inhibitors when studying receptor phosphorylation states

• Perform tissue homogenization in cold buffer to prevent protein degradation

• Typically load 20-50 μg of total protein per lane

• Use reducing conditions as specified for most FAA3/TGFBR2 antibodies

For Immunohistochemistry:

• Immersion fixation in paraformaldehyde is recommended

• Paraffin-embedded sections show consistent results at 3-5 μm thickness

• Antigen retrieval (typically heat-mediated) is essential for most applications

• Overnight incubation at 4°C with primary antibody concentration of 3-5 μg/mL provides optimal staining in human tissues

What are the recommended detection methods for FAA3/TGFBR2 antibodies?

The detection strategy should be tailored to the specific application:

HRP-DAB staining systems have been validated for FAA3/TGFBR2 antibody-based detection in paraffin-embedded tissue sections with counterstaining using hematoxylin .

How can researchers validate the specificity of FAA3/TGFBR2 antibodies?

Multiple validation approaches should be employed:

• Positive Control Testing - Use tissues with known TGFBR2 expression (small intestine, breast epithelial cells) to confirm expected staining patterns

• Molecular Weight Verification - Confirm detection of the expected molecular weight band (~70-80 kDa for full-length TGFBR2, or ~19 kDa for specific fragments depending on antibody epitope)

• Peptide Competition Assay - Pre-incubate antibody with immunizing peptide to confirm signal reduction

• Genetic Controls - Use TGFBR2 knockout or knockdown systems to verify signal loss

• Orthogonal Method Validation - Compare antibody results with mRNA expression data or alternative detection methods

How can phospho-specific FAA3/TGFBR2 antibodies be utilized to study receptor activation?

Phospho-specific antibodies targeting TGFBR2 (such as anti-TGFBR2 pS225) enable detailed mechanistic studies of receptor activation and signaling dynamics . These specialized antibodies detect specific phosphorylation events that occur during receptor activation.

Recommended Protocol:

• Stimulate cells with TGF-β ligands (1-5 ng/mL) for varying time points (5 min to 2 hours)

• Rapidly lyse cells in buffer containing phosphatase inhibitors (sodium fluoride, sodium orthovanadate)

• Perform Western blot analysis using phospho-specific antibodies

• Strip and reprobe membranes with total TGFBR2 antibodies

• Calculate phosphorylation-to-total protein ratios to quantify activation levels

This approach allows researchers to track the kinetics of receptor activation and compare signaling efficiency across experimental conditions or cell types.

What approaches are recommended for studying FAA3/TGFBR2 in complex with other signaling components?

Co-immunoprecipitation (Co-IP) experiments using FAA3/TGFBR2 antibodies can reveal physical interactions with:

• Type I TGF-β receptors (ALK5/TGFBR1)

• TGF-β ligands

• Downstream SMAD proteins

• Regulatory proteins (FKBP12, BAMBI)

Methodological Considerations:

• Use mild lysis conditions (1% NP-40 or Digitonin-based buffers)

• Include protease inhibitors and phosphatase inhibitors

• Perform IP at 4°C overnight with antibodies confirmed for IP applications

• Use protein A/G beads for rabbit-derived antibodies

• Include isotype controls to identify non-specific interactions

This approach enables researchers to map the dynamic protein complexes that form during TGF-β signaling.

What are common causes of false positives when using FAA3/TGFBR2 antibodies?

Several factors can contribute to false positive results:

• Cross-reactivity with related receptors - TGFBR2 shares structural similarities with other TGF-β family receptors, potentially leading to cross-reactivity. Always verify antibody specificity against related proteins.

• Non-specific binding to Fc receptors - Particularly problematic in immune cells and tissues. Include proper blocking steps (using 5-10% normal serum from the secondary antibody species) before primary antibody incubation.

• Endogenous peroxidase activity - For IHC applications, treat sections with hydrogen peroxide (0.3-3% for 10-30 minutes) before antibody incubation to quench endogenous peroxidase activity.

• Endogenous biotin - When using biotinylated detection systems, biotin blocking steps are essential, particularly with kidney, liver, and brain tissues.

• Excessive antibody concentration - Titrate antibodies carefully, as concentrations that are too high increase background staining.

How should researchers address inconsistent results between different FAA3/TGFBR2 antibodies?

Inconsistencies between antibodies targeting the same protein may arise from several factors:

• Epitope differences - Different antibodies may target distinct regions of TGFBR2 (N-terminal, C-terminal, or middle regions) . Document the specific epitope for each antibody used.

• Post-translational modifications - Some antibodies may have reduced binding to glycosylated, phosphorylated, or proteolytically processed forms of TGFBR2.

• Isoform specificity - TGFBR2 has multiple isoforms, and antibodies may have varying reactivity to each.

Recommended approach:

• Use multiple antibodies targeting different epitopes

• Document all experimental conditions precisely

• Compare results with orthogonal methods (mRNA expression, reporter systems)

• Consider the specific application - some antibodies perform better in certain applications than others

What quantitative standards should be applied when analyzing FAA3/TGFBR2 expression data?

For quantitative analysis of FAA3/TGFBR2 expression:

• Western blot quantification:

  • Always normalize to appropriate loading controls (β-actin, GAPDH, α-tubulin)

  • Use standard curves with recombinant proteins for absolute quantification

  • Report fold-changes relative to controls rather than absolute densitometry values

• ELISA quantification:

  • The detection range for TGFBR2 ELISA assays is typically 0.312-20 ng/mL with a sensitivity of approximately 0.112 ng/mL

  • Always run standard curves in duplicate or triplicate

  • Validate sample measurements within the linear range of the standard curve

• IHC/IF quantification:

  • Use digital image analysis with standardized acquisition parameters

  • Score staining intensity on defined scales (0-3+) for semi-quantitative analysis

  • For fluorescence quantification, use mean fluorescence intensity with background subtraction

How can FAA3/TGFBR2 antibodies contribute to cancer research?

FAA3/TGFBR2 antibodies serve as valuable tools in cancer research due to the protein's dual role as both tumor suppressor and promoter depending on cancer stage and context. Key research applications include:

• Diagnostic biomarker assessment - Evaluating TGFBR2 expression patterns across tumor types and correlating with clinical outcomes

• Therapeutic response monitoring - Tracking changes in TGFBR2 expression and activation following treatment with TGF-β pathway inhibitors

• EMT studies - Investigating TGFBR2's role in epithelial-mesenchymal transition, a critical process in metastasis

• Genetic instability analysis - TGFBR2 mutations (including microsatellite instability in the FAA3/TGFBR2 gene) are associated with certain cancer types, particularly colorectal cancers

What considerations are important when using FAA3/TGFBR2 antibodies in conjunction with other TGF-β pathway markers?

When designing multiplexing experiments:

• Antibody compatibility - Ensure primary antibodies are raised in different host species to avoid secondary antibody cross-reactivity

• Signal separation - Choose fluorophores with minimal spectral overlap when conducting multiplex immunofluorescence

• Sequential staining - For complex co-localization studies, consider sequential rather than simultaneous staining approaches

• Complementary markers - Pair TGFBR2 detection with other pathway components:

  • TGFBR1 (type I receptor partner)

  • SMAD2/3 (downstream signaling proteins)

  • SMAD4 (common mediator SMAD)

  • TGF-β ligands (TGFB1, TGFB2, TGFB3)