EXL6 is a member of Lipase proteins, also known as EXTRACELLULAR LIPASE 6 . The immunogen for EXL6 is AT1G75930 Q93X94 .
The E06 monoclonal antibody recognizes the phosphocholine headgroup of oxidized phospholipid that is present in oxidized LDL and PC-modified BSA, but does not bind to normal LDL or unoxidized PC . It is derived from the C57BL/6 hybridoma E06 and produced in vitro via cell culture and purified through ultrafiltration with 100 KDa cut-off filters, resulting in a purity of ≥ 95% . The antibody is provided as a sterile-filtered solution in phosphate-buffered saline (PBS) .
Oxidized lipids, particularly oxidized phospholipids (OxPL), are crucial in the development and pathology of inflammatory and some infectious diseases . Atherosclerosis, a chronic inflammatory disease, is significantly influenced by elevated plasma LDL, making oxidized LDL (OxLDL) with its associated OxPL a major factor in atherogenesis . The E06 monoclonal antibody can differentiate between native LDL and OxLDL by binding to the phosphocholine headgroup of OxPL, which is present in OxLDL but absent from native LDL . E06 can also detect OxPL in cells, tissues, membranes, and lipoproteins in various inflammatory settings .
The E06 antibody has applications in quantifying oxidized LDL in various methods:
It specifically binds to the PC headgroup of many oxidized phospholipids and inhibits the binding of ox-LDL to macrophages . A biotinylated form of E06 is utilized for enzyme-linked immunosorbent assay (ELISA) determination of ox-LDL in serum or plasma samples . A TopFluor-conjugated E06 antibody is available for immunohis- tochemistry (IHC) including confocal microscopy .
Competitive ELISA Protocol: To assess the specificity of E06 binding, microtitration plates are prepared. Various concentrations (0.1-20 µg/mL) of PC-BSA are included as a competition antigen along with 250 ng of E06 antibody. After incubation, the amount of IgM specifically bound to each well is quantitated with goat anti-mouse IgM-AP and a chemiluminescent substrate after 4h incubation at 4°C .
Sandwich ELISA Protocol: The E06 antibody is used as a detection antibody in a sandwich ELISA method. Microtiter wells are coated with the murine monoclonal antibody MB47 (5μg/mL) as a capture antibody to bind apo B-100. 1:50-diluted aliquots of plasma are added, followed by biotinylated E06 antibody and then streptavidin-linked HRP and a chemiluminescent substrate .
ELOVL6 (Elongation of Very Long Chain Fatty Acids Protein 6) is a crucial enzyme involved in fatty acid elongation pathways. This protein has gained significant research interest due to its role in lipid metabolism and potential implications in metabolic disorders.
Research utilizing ELOVL6 antibodies allows scientists to:
Track protein expression levels in various tissue types
Investigate subcellular localization patterns
Examine protein-protein interactions involving ELOVL6
Study metabolic pathway alterations in disease models
When selecting an ELOVL6 antibody, researchers should consider applications validated by manufacturers, such as immunohistochemistry (IHC), Western blotting, and ELISA, as these methods provide different but complementary data about protein presence and function .
Selecting the right antibody requires careful consideration of multiple factors:
Application compatibility: Confirm the antibody has been validated for your specific application (Western blot, IHC, ELISA, etc.)
Species reactivity: Ensure compatibility with your experimental model organism
Validation documentation: Review the manufacturer's validation data for specificity and sensitivity
Antibody type: Consider whether polyclonal or monoclonal antibodies better suit your research needs
Polyclonal antibodies like the rabbit anti-ELOVL6 antibody often provide high sensitivity by recognizing multiple epitopes but may exhibit batch-to-batch variation. For instance, some commercially available rabbit polyclonal ELOVL6 antibodies have been validated specifically for Western blot (1:500-1:2000 dilution) and ELISA (1:10000 dilution) applications .
Proper controls are essential for reliable antibody-based experiments:
| Control Type | Purpose | Implementation Method |
|---|---|---|
| Positive control | Confirms antibody functionality | Use samples known to express ELOVL6 |
| Negative control | Assesses non-specific binding | Use samples lacking ELOVL6 expression |
| Isotype control | Evaluates background binding | Use non-specific antibody of same isotype |
| Knockout/knockdown | Validates antibody specificity | Use genetically modified samples without target protein |
| Loading control | Normalizes protein amounts | Use housekeeping proteins (β-actin, GAPDH) |
According to established antibody validation frameworks, implementing at least two independent validation methods from the "five pillars" approach is recommended: genetic strategies (knockouts), orthogonal strategies, independent antibody strategies, recombinant expression, or immunocapture-MS .
Western blotting optimization for ELOVL6 requires attention to several critical parameters:
Sample preparation:
Use appropriate lysis buffers (e.g., buffer containing 20mM Tris pH 7.5, 140mM NaCl, 1mM EDTA, 10% glycerol, 1% Triton X-100)
Include protease inhibitors to prevent protein degradation
Maintain cold temperatures throughout processing
Antibody dilution optimization:
Start with manufacturer's recommended range (typically 1:500-1:2000 for ELOVL6)
Perform dilution series to identify optimal signal-to-noise ratio
Consider longer incubation at 4°C to improve specific binding
Blocking optimization:
Test different blocking agents (BSA vs. non-fat milk)
Adjust blocking time (1-2 hours at room temperature or overnight at 4°C)
Detection method selection:
Choose chemiluminescence for high sensitivity
Consider fluorescent detection for quantitative analysis
For membrane proteins like ELOVL6, sample denaturation conditions are particularly important to maintain epitope accessibility while ensuring proper protein separation .
Researchers frequently encounter these challenges when performing IHC with ELOVL6 antibodies:
Fixation artifacts: Overfixation can mask epitopes while underfixation leads to poor morphology
Solution: Optimize fixation time and conditions; consider antigen retrieval methods
Non-specific binding: Background staining obscuring specific signal
Solution: Increase blocking time, adjust antibody concentration, include additional washing steps
Variable staining intensity: Inconsistent results between experiments
Solution: Standardize tissue processing, maintain consistent incubation times and temperatures
False positives/negatives: Misinterpretation of staining patterns
Solution: Include proper controls, particularly knockout tissues if available
The NeuroMab approach provides a useful model for antibody validation, where approximately 1,000 clones are screened using multiple applications to identify truly specific antibodies. This two-step validation process significantly improves reliability over simple ELISA-based selection methods .
Determining epitope specificity is crucial for understanding potential cross-reactivity and interpreting experimental results:
Epitope mapping techniques:
Peptide arrays can identify linear epitopes by testing antibody binding to overlapping peptide fragments
Alanine scanning mutagenesis systematically replaces amino acids to identify critical binding residues
Hydrogen-deuterium exchange mass spectrometry (HDX-MS) identifies regions protected by antibody binding
Bioinformatic approaches:
Sequence homology analysis to identify related proteins with similar epitopes
Structural modeling to predict exposed regions likely to serve as epitopes
Similar to the approach used for X6 antibody characterization, researchers can create a set of peptides with systematic amino acid substitutions to identify critical residues for antibody binding. This technique revealed that for X6 antibody, the PFP motif was critical for recognition, with substitutions at positions 4-6 causing almost complete loss of antibody affinity .
Cross-reactivity represents a significant challenge for antibody specificity:
Preabsorption testing:
Incubate antibody with purified antigen before application
Compare staining patterns with and without preabsorption
Multi-species validation:
Test antibody against samples from different species to identify unexpected cross-reactivity
Particularly important when working with evolutionarily conserved proteins
Mass spectrometry verification:
Immunoprecipitate with the antibody and identify all captured proteins by MS
Confirms target specificity and reveals potential cross-reactants
From the X6 antibody example, we see how specificity testing can be performed using immunoblotting against multiple related proteins. This approach demonstrated that X6 antibody recognized proteins containing the QXQPFPXP epitope sequence, with varying degrees of affinity depending on epitope conservation .
Recent advances in computational modeling have enhanced our ability to design and predict antibody specificity:
Biophysics-informed modeling:
Identifies distinct binding modes associated with specific ligands
Enables prediction of antibody behavior beyond experimentally tested conditions
Facilitates design of antibodies with customized specificity profiles
Machine learning approaches:
Neural networks can parameterize the energy functions associated with antibody-antigen binding
Allows optimization of sequences for specific or cross-specific binding properties
Recent research has demonstrated that these computational models can successfully disentangle multiple binding modes associated with specific antigens, even when those antigens are chemically very similar. This approach has applications for creating antibodies with both specific and cross-specific binding properties .
Genetic validation represents the gold standard for antibody specificity:
Knockout/knockdown strategies:
CRISPR-Cas9 knockout cell lines provide definitive negative controls
siRNA knockdown offers an alternative when knockout is not feasible
Compare signal intensity between wild-type and modified samples
Overexpression approaches:
Transfect cells with ELOVL6 expression constructs
Verify increased signal intensity compared to non-transfected controls
Tagged protein expression:
Express epitope-tagged ELOVL6 and confirm co-localization with antibody staining
Allows differentiation between specific and non-specific signals
According to the "five pillars" framework for antibody validation, genetic strategies represent one of the most definitive approaches for confirming antibody specificity and should be implemented whenever possible .
Batch-to-batch variation affects experimental reproducibility, particularly with polyclonal antibodies:
Standardized validation protocols:
Implement consistent quality control testing for each batch
Maintain reference samples for comparative analysis
Recombinant antibody alternatives:
Consider switching to recombinant antibodies with defined sequences
Provides consistent performance across experiments
Internal reference standardization:
Include standardized positive controls in each experiment
Normalize results against these standards to account for batch differences
The scientific community increasingly recognizes that recombinant antibodies show superior reproducibility compared to polyclonal antibodies, as demonstrated in workshops by organizations like YCharOS and Abcam using knockout cell line testing .
When different methods yield conflicting results:
Methodological limitations assessment:
Each technique has inherent limitations (e.g., Western blot detects denatured epitopes while IHC may require native conformation)
Evaluate whether discrepancies reflect these methodological differences
Orthogonal validation approach:
Implement antibody-independent methods to verify findings
Use PCR to confirm transcript presence/absence
Consider mass spectrometry for protein identification
Multiple antibody strategy:
Test several antibodies targeting different epitopes
Consistent results across multiple antibodies increase confidence
Researchers should consider that antibody specificity is "context-dependent," requiring validation for each specific application and experimental context, as emphasized in the Alpbach Workshops on Affinity Proteomics .
Several cutting-edge approaches are transforming antibody research:
High-throughput sequencing integration:
Next-generation sequencing of antibody repertoires enables deeper characterization
Computational analysis identifies optimal candidates with desired properties
Structural biology advances:
Cryo-EM facilitates antibody-antigen complex visualization at near-atomic resolution
Enhances epitope mapping precision and guides optimization
AI-driven antibody design:
Machine learning algorithms predict antibody properties from sequence data
Accelerates development of highly specific antibodies with desired characteristics
These technologies are enabling researchers to disentangle different binding modes associated with specific antigens, even when the antigens cannot be experimentally dissociated from other epitopes present during selection .
Recombinant antibody technologies offer significant advantages:
Sequence-defined antibodies:
Eliminates batch-to-batch variation through precise genetic encoding
Enables reproducible experiments across different laboratories and timelines
Engineered specificity:
Targeted mutations can enhance binding affinity and specificity
Reduces off-target effects and improves experimental reliability
Standardized production:
Consistent manufacturing processes ensure uniform quality
Facilitates rigorous validation and characterization
Converting hybridoma-derived antibodies to recombinant formats, as demonstrated by NeuroMab, provides an optimal solution that maintains the desired specificity while improving reproducibility .