The search results provided focus on human antibodies, cancer immunotherapy, antibody structure, and commercial antibodies targeting proteins like CD357 (GITR) or CD137 (4-1BB) . None mention Arabidopsis thaliana gene At4g35733 or associated antibodies.
The prefix "At" typically denotes Arabidopsis thaliana genes. The identifier At4g35733 corresponds to a hypothetical protein-coding locus in this plant species. Key observations:
No antibodies targeting this locus are cataloged in major antibody databases (e.g., CiteAb, PLAbDab) .
Antibodies listed in the search results (e.g., anti-CD357, anti-4-1BB) are unrelated to plant biology .
While antibodies against plant proteins exist, their development requires:
Immunogen Design: Peptides or recombinant proteins derived from the target sequence.
Validation: Specificity testing via Western blot (WB) or immunohistochemistry (IHC) .
Commercial Availability: Antibodies for plant proteins are rare compared to human/mouse targets.
If investigating At4g35733:
Verify the Gene/Protein: Confirm its function and expression in Arabidopsis.
Custom Antibody Production: Services like Proteintech or BioLegend offer tailored antibody development .
Cross-Reactivity: Ensure antibodies against homologous proteins in other species do not exist.
For context, below is a comparison of antibodies against human proteins mentioned in the search results:
At4g35733 refers to a specific gene locus in the Arabidopsis thaliana genome. Antibodies developed against proteins encoded by this gene are valuable tools for studying its expression, localization, and function within plant tissues. These antibodies enable researchers to conduct immunoprecipitation, Western blotting, immunohistochemistry, and other immunological techniques to understand the role of this gene in plant development, stress responses, or other biological processes. Monoclonal antibodies offer high specificity for epitopes on the target protein, helping researchers precisely track protein expression patterns across different experimental conditions .
For plant proteins like those encoded by At4g35733, several expression systems can be utilized depending on research requirements. Bacterial systems (particularly E. coli) are commonly used for generating partial recombinant proteins with tags like GST that facilitate purification. For proteins requiring post-translational modifications, eukaryotic expression systems such as yeast, insect cells, or plant-based expression systems may be more appropriate. The choice should be guided by the protein's characteristics, including size, solubility, and whether native conformational epitopes need to be preserved for antibody recognition .
Thorough validation is essential before using antibodies in critical experiments. For At4g35733 antibodies, validation should include:
Western blot analysis using both recombinant protein and native plant extracts
Testing on wild-type versus knockout/knockdown plant tissues
Immunoprecipitation followed by mass spectrometry to confirm target specificity
Cross-reactivity testing with related proteins to ensure specificity
Epitope mapping to identify the recognized sequence
Additionally, antibodies should be tested in all applications where they will be used, as performance can vary between techniques. Detailed validation records should be maintained as they're crucial for result interpretation and troubleshooting .
To maximize antibody shelf life and maintain activity, follow these storage guidelines:
Store concentrated antibodies (supernatants or purified) at -20°C or -80°C for long-term storage
For periods less than one month, storage at 4°C is typically acceptable
Aliquot antibodies to avoid repeated freeze-thaw cycles which can degrade protein structure
Include appropriate preservatives (such as sodium azide) for solutions stored at 4°C
Store in appropriate buffer conditions (commonly phosphate buffered saline, pH 7.2)
Monitor for precipitates or color changes that might indicate deterioration
Proper labeling with antibody details, concentration, date prepared, and expiration information is essential for laboratory management .
When At4g35733 antibodies exhibit cross-reactivity with unintended targets, several approaches can address this challenge:
Perform comprehensive epitope mapping to identify the specific sequence recognized by the antibody
Analyze sequence homology between At4g35733 and potential cross-reactive proteins using bioinformatics tools
Develop competitive blocking assays using synthetic peptides matching the epitope
Consider using multiple antibodies targeting different epitopes of At4g35733 to confirm results
Implement pre-adsorption protocols with recombinant proteins containing the cross-reactive epitopes
A methodical approach to addressing cross-reactivity involves systematically identifying the source of interference and developing specific protocols to mitigate it. This may include redesigning experiments to include appropriate controls or generating new antibodies with improved specificity .
Low-abundance proteins present significant detection challenges. For At4g35733, consider these approaches:
Signal amplification techniques:
Tyramide signal amplification for immunohistochemistry
Poly-HRP conjugated secondary antibodies
Biotin-streptavidin amplification systems
Sample enrichment methods:
Subcellular fractionation to concentrate the target protein
Immunoprecipitation prior to Western blotting
Protein concentration methods appropriate for plant tissues
Enhanced detection systems:
Chemiluminescence with extended exposure times
Digital imaging systems with high sensitivity
Fluorescence-based detection with appropriate filters
Consider creating transgenic plants with epitope-tagged versions of At4g35733 for easier detection when native antibodies provide insufficient sensitivity .
Detecting and distinguishing post-translational modifications (PTMs) of At4g35733 requires specialized antibody approaches:
Modification-specific antibodies:
Use antibodies specifically raised against the modified form (phosphorylated, glycosylated, etc.)
Compare detection patterns with antibodies recognizing the non-modified protein
Enzymatic treatments:
Treat samples with phosphatases, glycosidases, or other enzymes to remove specific modifications before antibody detection
Observe changes in binding patterns or mobility shifts
Two-dimensional electrophoresis:
Separate proteins by isoelectric point and molecular weight
Use antibodies to detect different modified forms appearing as distinct spots
Mass spectrometry validation:
Combine immunoprecipitation with mass spectrometry analysis
Map modifications and their positions to correlate with antibody recognition patterns
This multi-technique approach provides robust evidence for PTM presence and distribution .
Cross-species application of At4g35733 antibodies requires careful methodological considerations:
Sequence homology analysis:
Compare protein sequences between species to predict conservation of epitopes
Focus on antibodies targeting highly conserved regions
Protocol modifications:
Adjust extraction buffers to accommodate differences in cellular composition
Modify blocking agents to reduce background in different tissues
Alter incubation times and antibody concentrations based on empirical testing
Validation requirements:
Confirm specificity using recombinant proteins from the target species
Perform knockout/knockdown controls in the new species when possible
Consider using orthogonal detection methods to confirm findings
Cross-reactivity assessment:
| Species | Sequence similarity | Expected reactivity | Recommended dilution | Validation method |
|---|---|---|---|---|
| Arabidopsis | 100% | Strong | 1:1000 | Western blot, IP, IHC |
| Tomato | Moderate | Variable | 1:500 | Western blot |
| Lettuce | Moderate | Variable | 1:500 | Western blot |
| Other Brassicaceae | High | Likely | 1:750 | Western blot |
| Non-related plants | Low | Unlikely | Test at 1:250 | Multiple methods |
Systematic testing and optimization are essential when extending antibody applications to new species .
Epitope preservation is critical for successful immunohistochemistry with At4g35733 antibodies:
Fixative selection:
4% paraformaldehyde offers good balance between structure preservation and epitope accessibility
Assess alternate fixatives (glutaraldehyde, methanol-acetone) if epitope detection is compromised
Consider comparing multiple fixation methods in parallel
Fixation protocol:
Optimize fixation duration (typically 4-24 hours depending on tissue size)
Control temperature during fixation (4°C typically reduces over-fixation)
Ensure proper tissue penetration through vacuum infiltration for plant tissues
Antigen retrieval methods:
Heat-induced epitope retrieval using citrate buffer (pH 6.0)
Enzymatic retrieval using proteinase K or other proteases
Test multiple retrieval methods if initial results are unsatisfactory
Tissue-specific considerations:
Young tissues may require shorter fixation times
Lignified tissues might need additional permeabilization steps
Highly vacuolated cells may require specialized infiltration approaches
Systematic optimization of these parameters is essential for consistent immunolocalization results .
Non-specific background in Western blots can obscure true signals. Consider these troubleshooting approaches:
Sample preparation optimization:
Include protease inhibitors to prevent degradation products
Optimize protein extraction buffers for plant tissues
Consider additional purification steps before electrophoresis
Blocking optimization:
Test different blocking agents (BSA, non-fat milk, commercial blockers)
Increase blocking time or blocker concentration
Add low concentrations of detergents to reduce hydrophobic interactions
Antibody dilution and incubation:
Titrate primary antibody to determine optimal concentration
Extend washing steps after antibody incubations
Consider overnight incubations at 4°C rather than shorter incubations at room temperature
Detection system modifications:
Reduce substrate incubation time for enzymatic detection methods
Try alternative secondary antibodies
Consider fluorescent detection systems which may offer improved signal-to-noise ratios
Membrane considerations:
Ensure complete transfer of proteins to the membrane
Consider alternative membrane types (PVDF vs. nitrocellulose)
Verify removal of SDS through sufficient washing
Methodical testing of these variables helps identify the specific factors contributing to background issues .
Robust co-immunoprecipitation experiments require comprehensive controls:
Input controls:
Total lysate samples to confirm presence of target proteins before IP
Quantitative analysis to determine IP efficiency
Negative controls:
IgG control from the same species as the primary antibody
IP from knockout/knockdown plant tissues
Beads-only control to identify non-specific binding to the matrix
Reciprocal IPs:
Perform IP with antibodies against the suspected interacting partner
Confirm interactions in both directions when possible
Competition controls:
Include excess antigen peptide to demonstrate binding specificity
Titrate competing peptide to show concentration-dependent effects
Buffer optimization controls:
Test different salt concentrations to distinguish specific from non-specific interactions
Evaluate detergent types and concentrations to preserve interactions while reducing background
Validation controls:
| Control type | Purpose | Expected result |
|---|---|---|
| Input sample | Confirm target presence | Positive signal |
| IgG control | Assess non-specific binding | No signal |
| Knockout tissue | Verify antibody specificity | No signal |
| Peptide competition | Confirm epitope specificity | Reduced/eliminated signal |
| Stringency test | Determine interaction strength | Signal decreases with increasing stringency |
These controls help discriminate true interactions from experimental artifacts .
Accurate quantification and normalization are essential for comparative studies:
Quantification methods:
Densitometry analysis of Western blots using appropriate software
ELISA-based quantification with standard curves
Fluorescence-based quantification with directly labeled antibodies
Normalization strategies:
Use housekeeping proteins appropriate for plant tissues (actin, tubulin, GAPDH)
Validate stability of reference proteins under experimental conditions
Consider total protein normalization using stain-free technology or Ponceau staining
Technical considerations:
Ensure linear range of detection for both target and reference proteins
Include standard curves with recombinant protein when possible
Run biological and technical replicates to assess variance
Advanced approaches:
Consider multiple reference proteins and geometric averaging for normalization
Implement absolute quantification using purified standards
Use spike-in controls for sample-to-sample normalization
Statistical validation:
Apply appropriate statistical tests based on experimental design
Perform power analysis to determine adequate sample size
Consider normality of data distribution when selecting statistical approaches
This comprehensive approach provides reliable quantification across diverse experimental conditions .
Studying protein-protein interactions requires careful experimental design:
Method selection based on interaction characteristics:
Co-immunoprecipitation for stable, direct interactions
Proximity labeling for transient or weak interactions
Split reporter systems for in vivo validation
Yeast two-hybrid as a complementary approach
Control design:
Include positive controls with known interacting partners
Implement negative controls with proteins not expected to interact
Design experiments to distinguish direct vs. indirect interactions
Validation strategy:
Confirm interactions using multiple, orthogonal methods
Validate biological relevance through functional assays
Consider domain mapping to identify interaction interfaces
Experimental conditions:
Test interactions under native and stress conditions
Consider temporal dynamics of interactions during development
Evaluate subcellular localization constraints
Data analysis framework:
Establish clear thresholds for defining positive interactions
Implement appropriate statistical analysis for replicate experiments
Consider network analysis for multiple interaction partners
These considerations help ensure robust, reproducible interaction studies with biological relevance .
ChIP optimization for plant tissues requires specific adaptations:
Crosslinking optimization:
Test different formaldehyde concentrations (1-3%)
Optimize crosslinking time (10-30 minutes) for plant tissues
Consider vacuum infiltration to ensure uniform fixation
Chromatin preparation:
Adapt nuclei isolation protocols for plant-specific cell walls
Optimize sonication parameters for plant chromatin fragmentation
Verify fragment size distribution through gel electrophoresis
Immunoprecipitation conditions:
Determine optimal antibody concentration through titration experiments
Test different incubation times and temperatures
Consider pre-clearing steps to reduce background
Washing stringency:
Develop appropriate washing protocols to balance signal retention and background reduction
Include controls with increasing washing stringency to optimize signal-to-noise ratio
DNA recovery and analysis:
Compare different DNA purification methods for yield and purity
Implement appropriate controls for qPCR analysis
Consider sequencing depth requirements for ChIP-seq applications
Plant-specific considerations:
Account for endogenous plant compounds that may interfere with immunoprecipitation
Consider tissue-specific optimization due to varying chromatin accessibility
Adapt protocols for different developmental stages or stress conditions
These optimizations help overcome the unique challenges of plant ChIP experiments .
Rigorous characterization of antibody specificity requires multiple approaches:
Genetic validation:
Test antibodies on knockout/knockdown plant lines
Use overexpression lines to confirm signal increase
Compare multiple independent mutant alleles when available
Biochemical validation:
Perform peptide competition assays with the immunizing antigen
Test cross-reactivity with related proteins through Western blotting
Use recombinant protein arrays to assess broader specificity
Analytical approaches:
Perform immunoprecipitation followed by mass spectrometry
Compare results across multiple antibody lots
Evaluate consistency across different applications (Western, IP, IHC)
Systematic validation series:
| Validation approach | Purpose | Interpretation |
|---|---|---|
| Knockout tissue testing | Confirm specificity | Loss of signal indicates specificity |
| Overexpression testing | Verify target detection | Increased signal confirms detection |
| Peptide competition | Identify epitope specificity | Dose-dependent signal reduction |
| IP-MS | Identify all targets | Single major hit indicates specificity |
| Cross-reactivity panel | Assess related protein binding | Minimal binding to non-targets |
These approaches provide a comprehensive assessment of antibody specificity and suitability for specific applications .
Contradictory results require systematic troubleshooting and interpretation:
Method-specific considerations:
Evaluate whether techniques detect native vs. denatured proteins
Consider epitope accessibility differences between methods
Assess whether methods detect different pools of the protein (membrane-bound vs. soluble)
Analytical approach:
Compare antibodies targeting different epitopes of At4g35733
Correlate protein detection with mRNA expression data
Implement orthogonal, non-antibody-based detection methods
Technical validation:
Review all positive and negative controls for each method
Assess reagent quality and experimental conditions
Consider biological variability in the samples being analyzed
Biological interpretation:
Evaluate whether contradictions reflect actual biological complexity
Consider post-translational modifications affecting epitope recognition
Assess potential protein interactions masking epitopes
Resolution strategy:
Design decisive experiments that can explain the contradictions
Implement multiple detection methods in parallel
Consider developing new reagents if existing ones prove inadequate
Data acquisition considerations:
Ensure linearity of detection system within the analyzed range
Include technical and biological replicates
Control for loading variation through appropriate normalization
Normalization approaches:
Ratio to housekeeping proteins (validated for stability under experimental conditions)
Total protein normalization (Ponceau S, stain-free technology)
Spiked internal standards for absolute quantification
Statistical methods:
For normally distributed data: ANOVA with appropriate post-hoc tests
For non-parametric data: Kruskal-Wallis or similar approaches
For time-series data: repeated measures ANOVA or mixed-effects models
Advanced considerations:
Power analysis to determine adequate sample size
Multiple testing correction for complex experimental designs
Consideration of experimental batch effects
Presentation guidelines:
Include measures of variance (standard deviation or standard error)
Present individual data points alongside means/medians
Clearly indicate statistical significance and test methods
These approaches ensure robust analysis of semi-quantitative data from immunoblot experiments .
Inconsistent results can be addressed through systematic troubleshooting:
Antibody variables:
Lot-to-lot variation in commercial antibodies
Antibody degradation due to improper storage
Inconsistent antibody dilutions or incubation conditions
Sample preparation factors:
Variations in protein extraction efficiency
Inconsistent sample handling affecting protein integrity
Buffer composition changes affecting epitope accessibility
Technical considerations:
Variations in transfer efficiency for Western blots
Inconsistent blocking effectiveness
Detection system variability
Biological variables:
Growth condition variations affecting protein expression
Developmental stage differences between experiments
Circadian or diurnal regulation of target protein
Systematic resolution approach:
| Issue | Diagnostic approach | Solution strategy |
|---|---|---|
| Antibody degradation | Test new vs. old aliquots | Prepare fresh aliquots, verify storage |
| Protocol inconsistency | Document all steps precisely | Implement detailed SOPs |
| Sample variation | Compare extraction methods | Standardize sample preparation |
| Technical variation | Include internal controls | Implement quality control checkpoints |
| Biological variation | Monitor growth conditions | Synchronize plant material carefully |
This systematic approach helps identify and address sources of variability .
Determining optimal antibody concentration requires empirical testing:
Titration experiments:
Test a wide concentration range (typically 1:100 to 1:10,000 dilutions)
Evaluate signal-to-noise ratio at each concentration
Include positive and negative controls at each concentration
Application-specific considerations:
Western blotting typically requires lower antibody concentrations than immunohistochemistry
ELISA may require different optimal concentrations than immunoprecipitation
Flow cytometry applications may require higher concentrations than Western blotting
Optimization strategy:
Start with manufacturer's recommended dilution (if available)
Perform initial broad-range titration
Refine with narrow-range titration around promising concentrations
Evaluation criteria:
Signal intensity at expected molecular weight/location
Background level and non-specific binding
Consistency across replicates
Cost-effectiveness of antibody usage
Documentation and standardization:
Record optimal concentrations for each application
Document lot numbers and potential variation between lots
Establish standard curves for quantitative applications
This methodical approach ensures optimal antibody performance while minimizing reagent usage .
Adapting antibodies for high-throughput applications requires specific considerations:
Assay miniaturization:
Develop microplate-based ELISA protocols
Optimize dot blot or slot blot approaches for rapid screening
Implement automated Western blot systems with standardized protocols
Automation compatibility:
Standardize all reagents for robot handling
Develop protocols with minimal manual intervention steps
Validate reproducibility across automated runs
Data acquisition systems:
Implement automated imaging systems with standardized settings
Develop image analysis algorithms for consistent quantification
Establish quality control metrics for automated data processing
Throughput enhancements:
Multiplex detection with antibodies against multiple targets
Develop tissue microarrays for simultaneous analysis of multiple samples
Implement batch processing protocols with appropriate controls
Validation and quality control:
Include standard samples across plates/batches
Implement automated outlier detection
Develop statistical approaches for large dataset analysis
These adaptations enable scaling antibody-based assays for large studies while maintaining data quality .
Several emerging technologies show promise for protein detection:
Aptamer-based approaches:
DNA/RNA aptamers selected for specific protein binding
Advantages include synthetic production and stability
Applications in biosensors and affinity purification
Nanobody technology:
Single-domain antibody fragments derived from camelid antibodies
Smaller size enables access to restricted epitopes
Enhanced stability and recombinant production
CRISPR-based protein detection:
Cas13-based detection systems adapted for protein targets
Potential for enhanced sensitivity through nucleic acid amplification
Multiplexed detection capabilities
Mass spectrometry advances:
Targeted proteomics with increasing sensitivity
Label-free quantification improvements
Simplified sample preparation workflows
Proximity labeling technologies:
BioID, APEX, and related approaches for in vivo protein detection
Spatial and temporal resolution of protein localization
Ability to detect weak or transient interactions
These technologies offer complementary approaches to traditional antibody methods, potentially addressing current limitations in specificity, throughput, and quantification .