AR (Ab-650) Antibody

What is AR (Ab-650) Antibody and what epitope does it recognize?

The AR (Ab-650) Antibody is a rabbit polyclonal antibody specifically designed to recognize the Androgen Receptor (AR) when phosphorylated at serine 650. The antibody was developed using a synthetic phosphopeptide immunogen containing the amino acid sequence T-T-S(p)-P-T derived from the human Androgen Receptor . The antibody targets a specific post-translational modification that plays a significant role in AR signaling regulation.

For optimal specificity, this antibody has been purified through a two-step process: affinity chromatography using the epitope-specific phosphopeptide, followed by removal of non-phospho-specific antibodies through additional chromatography with non-phosphopeptide . This careful purification ensures high specificity for the phosphorylated form of the receptor.

What applications is AR (Ab-650) Antibody validated for?

The AR (Ab-650) antibody has been specifically validated for two primary applications:

• Western Blotting (WB): Effective for detecting phosphorylated AR (Ser650) in cell and tissue lysates, allowing quantitative analysis of phosphorylation status under different experimental conditions .

• Immunohistochemistry on Paraffin-embedded sections (IHC-P): Validated for detecting phosphorylated AR in fixed tissue specimens, enabling spatial localization analysis within tissue architecture .

Both applications have been demonstrated in the product documentation with supporting evidence through example images showing specific detection in 293 cells for Western blot and human breast carcinoma tissue for IHC-P . The antibody shows distinct signal patterns that can be blocked with the specific phosphopeptide, confirming its specificity.

What samples and species can be effectively analyzed with this antibody?

The antibody has been tested and confirmed to react with human and mouse samples . Specifically:

For tissue samples, the antibody has been specifically validated with human breast carcinoma tissue sections prepared through standard formalin fixation and paraffin embedding procedures . For cell lines, 293 cells have been successfully used in Western blot applications, with specific detection demonstrated through comparative analysis of phosphatase-treated samples and PMA-stimulated samples .

What are the optimal storage and handling conditions for maintaining antibody activity?

To preserve antibody activity and specificity, follow these research-validated storage protocols:

• Short-term storage (up to one week): Store undiluted antibody at 2-8°C

• Long-term storage: Aliquot and store at -20°C

• Avoid storage in frost-free freezers due to temperature cycling

• Minimize freeze/thaw cycles as they degrade antibody performance

• Centrifuge vial briefly before opening to collect solution

• Gently mix before use rather than vortexing vigorously

The antibody is supplied in a stabilizing solution containing PBS (without Mg²⁺ and Ca²⁺, pH 7.4), 150mM NaCl, 0.02% sodium azide, and 50% glycerol . This formulation helps maintain antibody stability during storage.

How does phosphorylation at Ser650 affect Androgen Receptor function and signaling?

Phosphorylation at Ser650 represents a critical regulatory mechanism within the broader context of AR post-translational modifications. The Androgen Receptor functions as a steroid hormone-activated transcription factor that regulates gene expression affecting cellular proliferation and differentiation in target tissues .

Ser650 phosphorylation occurs within the hinge region connecting the DNA-binding domain and the ligand-binding domain. This phosphorylation has been implicated in:

• Modulating AR nuclear trafficking

• Regulating interactions with coregulatory proteins

• Affecting AR transcriptional activity

Research methodologies to study these effects include:

• Comparative transcriptomic analysis using phospho-mimetic (S650D/E) and phospho-deficient (S650A) AR mutants

• Chromatin immunoprecipitation (ChIP) studies with AR (Ab-650) to identify differential genomic binding sites

• Co-immunoprecipitation experiments to identify phosphorylation-dependent protein interactions

The phosphorylation of AR at Ser650 should be analyzed within the context of other post-translational modifications, including sumoylation at Lys-388 and Lys-521, ubiquitination (particularly 'Lys-6' and 'Lys-27'-linked polyubiquitination by RNF6), and phosphorylation at other sites such as Tyr-535 and Ser-83 .

What are the optimal experimental conditions for detecting phospho-AR (Ser650) in various research contexts?

Experimental optimization is critical for reliable detection of phospho-AR (Ser650). Based on research applications:

For Western Blot detection:

• Stimulation conditions: Treatment with PMA has been demonstrated to enhance phosphorylation at Ser650, providing a positive control

• Negative controls: Treatment with calf intestinal phosphatase (CIP) effectively dephosphorylates AR, providing a specificity control

• Sample preparation: Rapid sample collection and processing with phosphatase inhibitors is crucial to preserve phosphorylation status

• Blocking: 5% BSA in TBST is generally more effective than milk-based blockers when detecting phosphorylated proteins

• Antibody concentration: Optimizing dilution factors empirically for each cell line/tissue is recommended

For IHC-P applications:

• Antigen retrieval: Critical step requiring optimization (typically citrate or EDTA-based)

• Control tissues: Include known positive tissues (human breast carcinoma has been validated)

• Blocking peptide controls: Include parallel sections treated with antibody pre-incubated with blocking peptide to confirm specificity

• Signal amplification systems: May be required for low-abundance phosphorylation detection

How can AR (Ab-650) Antibody be integrated into multiplex studies of AR signaling networks?

For comprehensive analysis of AR signaling networks, AR (Ab-650) antibody can be integrated into multiplex studies through:

• Sequential Immunofluorescence:

  • First detection with AR (Ab-650) followed by stripping and reprobing with antibodies against:

    • Total AR to determine phosphorylation stoichiometry

    • Upstream kinases (PKC, MAPK)

    • Downstream transcriptional targets

  • Critical controls include single-antibody staining to confirm absence of cross-reactivity

• Proximity Ligation Assays (PLA):

  • Combine AR (Ab-650) with antibodies against potential interacting proteins

  • This enables visualization of protein interactions that depend on Ser650 phosphorylation

  • Requires careful optimization of primary antibody concentrations

• Phosphorylation-specific protein complex analysis:

  • Immunoprecipitation with AR (Ab-650) followed by mass spectrometry

  • Allows identification of protein complexes specifically associated with phospho-Ser650 AR

  • Compare with immunoprecipitation using total AR antibodies to identify phosphorylation-dependent interactions

What experimental approaches can resolve contradictory results when using AR (Ab-650) Antibody?

When facing contradictory results with AR (Ab-650) antibody, implement these methodological approaches:

• Validation through multiple detection methods:

  • Confirm phosphorylation status using both Western blot and IHC-P

  • Consider mass spectrometry-based validation for absolute confirmation

  • Use phosphatase treatment controls to verify signal specificity

• Cell line and context-dependent considerations:

  • Androgen receptor phosphorylation patterns vary significantly between cell types

  • Document and control hormone status of culture media (phenol red, serum factors)

  • Record cell confluence and passage number as these affect receptor expression and signaling

• Kinase/phosphatase dynamics:

  • Map the temporal dynamics of phosphorylation after stimulation

  • Identify cell-specific phosphatases that may rapidly dephosphorylate Ser650

  • Consider inhibitor panels to identify responsible kinases in your specific model system

• Antibody validation protocols:

  • Perform specificity tests using blocking peptide

  • Compare results with genetic approaches (CRISPR-modified AR-S650A cells)

  • Consider epitope masking effects due to protein-protein interactions

How can quantitative analysis be optimized when using AR (Ab-650) Antibody in tissue microarrays?

For rigorous quantitative analysis in tissue microarrays (TMAs) using AR (Ab-650) antibody:

• Staining standardization:

  • Include control tissues on each TMA slide

  • Process all TMA sections in parallel to minimize batch effects

  • Use automated staining platforms if available to ensure consistency

• Digital pathology approaches:

  • Implement whole-slide scanning with standardized acquisition parameters

  • Develop specific algorithms distinguishing nuclear from cytoplasmic phospho-AR staining

  • Use machine learning classifiers trained on expert-annotated regions

• Quantification methodology:

  • Implement H-score system (intensity × percentage of positive cells)

  • Alternative: Allred scoring system or digital intensity quantification

  • Report both staining intensity and subcellular localization patterns

• Statistical considerations:

  • Account for tumor heterogeneity through multiple core analysis

  • Implement intra-observer and inter-observer validation

  • Correlate with other biomarkers including total AR expression and clinical outcomes

What are the most common sources of false results when using AR (Ab-650) Antibody?

To avoid false results when working with AR (Ab-650) antibody, researchers should address these common issues:

• Phosphorylation instability:

  • Rapid loss of phosphorylation during sample preparation

  • Solution: Incorporate phosphatase inhibitors in all buffers, maintain samples at 4°C

• Cross-reactivity concerns:

  • Potential recognition of similar phosphorylation motifs in other proteins

  • Solution: Include blocking peptide controls to confirm specificity

• Fixation artifacts in IHC:

  • Overfixation can mask phospho-epitopes

  • Solution: Optimize fixation time and antigen retrieval conditions

  • Validate with positive control tissues (breast carcinoma has been confirmed)

• Antibody lot variations:

  • Different lots may have subtle specificity differences

  • Solution: Maintain reference samples for inter-lot comparison

  • Document lot numbers used for published experiments

How should researchers design experiments to distinguish between AR phosphorylation states?

To effectively distinguish between different AR phosphorylation states:

• Multiplexed phosphorylation analysis:

  • Compare AR (Ab-650) with antibodies against other phosphorylation sites (Ser-83, Tyr-535)

  • This allows mapping of phosphorylation patterns in different cellular contexts

  • Critical for understanding phosphorylation hierarchy and potential cross-talk

• Kinase modulation experiments:

  • Implement kinase inhibitor panels to identify responsible kinases

  • Design studies with constitutively active or dominant-negative kinase constructs

  • These approaches help establish causal relationships between signaling pathways and Ser650 phosphorylation

• Phosphorylation site mutants:

  • Generate cell models expressing AR-S650A to confirm antibody specificity

  • Compare with phosphomimetic mutants (S650D or S650E)

  • Essential for determining the functional consequences of phosphorylation

• Temporal dynamics studies:

  • Monitor phosphorylation kinetics following hormone or growth factor stimulation

  • Design time-course experiments with multiple sampling points

  • Important for understanding the dynamic regulation of AR phosphorylation

How might AR (Ab-650) Antibody be utilized in emerging single-cell analysis platforms?

Emerging opportunities for AR (Ab-650) antibody in single-cell analysis include:

• Single-cell phosphoproteomics:

  • Integration with mass cytometry (CyTOF) for multiplexed phosphoprotein detection

  • Development of compatible metal-conjugated AR (Ab-650) antibodies

  • Statistical frameworks for analyzing phosphorylation heterogeneity in tumor samples

• Spatial transcriptomics correlation:

  • Combined protein and RNA analysis to correlate phospho-AR status with gene expression

  • Implementation in platforms like GeoMx or 10X Visium

  • Bioinformatic approaches to integrate phosphoprotein data with transcriptional outputs

• Live-cell phosphorylation monitoring:

  • Development of compatible intrabodies or nanobodies recognizing the phospho-Ser650 epitope

  • Adaptation for intravital imaging applications

  • Computational approaches for analyzing dynamic phosphorylation changes

What are the key considerations for using AR (Ab-650) Antibody in translational research?

For translational applications of AR (Ab-650) antibody:

• Clinical sample optimization:

  • Standardize protocols for clinical tissue processing to preserve phosphorylation

  • Develop robust scoring systems applicable across institutions

  • Establish clinically relevant thresholds through retrospective validation studies

• Prognostic/predictive biomarker development:

  • Correlate phospho-Ser650 status with:

    • Treatment response in hormone-sensitive cancers

    • Resistance mechanisms in castration-resistant prostate cancer

    • Disease progression metrics in breast cancer

• Pharmacodynamic marker applications:

  • Monitor phospho-Ser650 changes during therapeutic interventions

  • Design of sequential biopsy studies to track phosphorylation dynamics

  • Integration with other molecular markers in multivariate predictive models

• Technical standardization for multi-center studies:

  • Development of reference standards and control materials

  • Proficiency testing across laboratories

  • Digital pathology tools for centralized review and quantification