adgra2 Antibody

What is ADGRA2 and why is it significant for research?

ADGRA2 (Adhesion G Protein-Coupled Receptor A2), also known as GPR124 or TEM5, is a critical endothelial receptor that functions with RECK to enable brain endothelial cells to selectively respond to Wnt7 signals (WNT7A or WNT7B). It plays a key role in Wnt7-specific responses, including endothelial cell sprouting and migration in the forebrain and neural tube, and establishment of the blood-brain barrier. ADGRA2 acts as a Wnt7-specific coactivator of canonical Wnt signaling by assembling a higher-order RECK-ADGRA2-Fzd-LRP5-LRP6 complex . Its research significance stems from its crucial involvement in cerebrovascular development and potential implications for understanding developmental disorders and vascular pathologies.

What is the molecular structure of ADGRA2?

ADGRA2 is a member of the adhesion-GPCR family characterized by an extended extracellular region coupled to a TM7 domain via a GPCR-Autoproteolysis INducing (GAIN) domain . The extracellular N-terminus of ADGRA2 comprises multiple protein-protein interaction domains, sequentially composed of:

• N-terminal leucine-rich repeat (LRR/CT) domain containing four LRR units

• Immunoglobulin-like (Ig-like) domain

• Hormone receptor motif (HRM)

• Membrane-proximal GPS-containing GAIN domain

The intracellular part is characterized by a PDZ binding domain . This complex structure facilitates ADGRA2's multiple interaction capabilities and signaling functions.

What are the most common applications for ADGRA2 antibodies in research?

ADGRA2 antibodies are most commonly utilized in:

• Western Blot (WB): For detecting ADGRA2 protein expression levels

• Immunofluorescence (IF): For visualizing localization patterns

• Immunohistochemistry (IHC): For tissue expression analysis

• Immunocytochemistry (ICC): For cellular distribution studies

• ELISA: For quantitative measurement of ADGRA2 levels

These applications enable researchers to investigate ADGRA2 expression, localization, and interactions in various experimental contexts.

What dilution ranges are optimal for different ADGRA2 antibody applications?

Based on validated research protocols, the following dilution ranges are recommended for ADGRA2 antibodies:

These ranges serve as starting points for optimization, with actual working concentrations determined by each researcher based on their specific experimental system, antibody lot, and detection method sensitivity .

How should proximity ligation assays (PLA) be designed to study ADGRA2 interactions?

For optimal PLA experiments investigating ADGRA2 interactions:

• Cell preparation: Culture endothelial cells (e.g., HUVECs) under appropriate conditions

• Fixation: Use 4% paraformaldehyde to preserve protein interactions

• Permeabilization: Apply 0.1% Triton X-100 to allow antibody access

• Blocking: Block with appropriate serum to reduce non-specific binding

• Primary antibodies: Incubate with antibodies against ADGRA2 and its potential interacting partner (e.g., RECK, Elmo2, or ITSN1)

• PLA probes: Apply secondary antibodies linked to oligonucleotides

• Ligation and amplification: Perform according to kit protocol

• Visualization: Detect PLA signals as red dots using fluorescence microscopy

• Quantification: Normalize PLA signals to cell number (DAPI) to obtain average PLA counts per cell

Controls should include single primary antibody conditions to establish background signal levels. This approach has successfully demonstrated endogenous interactions between ADGRA2 and Elmo2/ITSN1 in endothelial cells .

What controls are essential when validating ADGRA2 antibody specificity?

Essential controls for validating ADGRA2 antibody specificity include:

• Positive tissue/cell controls: Use samples known to express ADGRA2 (e.g., brain endothelial cells)

• Negative tissue/cell controls: Use samples known not to express ADGRA2

• Blocking peptide experiments: Pre-incubate antibody with blocking peptide corresponding to the immunogen sequence

• Knockdown validation: Perform siRNA/shRNA-mediated knockdown of ADGRA2

• Knockout validation: Use CRISPR/Cas9-engineered cell lines lacking ADGRA2

• Secondary antibody-only control: Omit primary antibody to assess non-specific binding

• Isotype control: Use non-specific IgG from the same species as the primary antibody

• Cross-reactivity assessment: Test antibody against overexpressed ADGRA2 and related family members

Comprehensive validation ensures experimental rigor and reproducibility in ADGRA2 research .

How can ADGRA2 antibodies be used to investigate its role in blood-brain barrier formation?

To investigate ADGRA2's role in blood-brain barrier (BBB) formation:

• Developmental analysis: Use ADGRA2 antibodies for immunostaining of brain sections at various embryonic stages to track expression patterns during BBB formation

• Co-localization studies: Perform double immunostaining with ADGRA2 antibodies and markers for:

  • Endothelial cells (CD31, VE-cadherin)

  • Tight junction proteins (ZO-1, claudin-5, occludin)

  • Wnt signaling components (β-catenin, LEF1)

  • RECK (known ADGRA2 partner)

• Functional analysis: Create conditional knockout or knockdown models, then use antibodies to assess:

  • Vascular density and morphology

  • Tight junction formation

  • Barrier integrity (via permeability markers)

• Proximity ligation assays: Use ADGRA2 antibodies with antibodies against Wnt7a/b, RECK, or frizzled receptors to detect protein-protein interactions in situ

• Protein complex isolation: Employ antibodies for co-immunoprecipitation followed by mass spectrometry to identify novel interacting partners during BBB development

This multi-faceted approach leverages ADGRA2 antibodies to comprehensively characterize its mechanistic contributions to BBB formation .

What methodologies can be employed to study ADGRA2 LRR domain's role in trafficking?

To investigate the critical role of the LRR domain in ADGRA2 trafficking:

• Domain-specific antibodies: Use antibodies targeting specific regions to track different ADGRA2 variants

• Deletion constructs: Generate in-frame deletions of individual LRR repeats (ΔLRR1-4) or combinations

• Subcellular fractionation: Isolate membrane, ER, and cytosolic fractions and perform Western blotting with ADGRA2 antibodies

• Co-localization immunofluorescence: Perform double staining with:

  • ADGRA2 antibodies

  • ER markers (calnexin, BiP/GRP78)

  • Golgi markers (GM130)

  • Plasma membrane markers (Na+/K+ ATPase)

• Live-cell trafficking: Create fluorescently tagged ADGRA2 variants and perform time-lapse imaging

• Glycosylation analysis: Assess N-glycosylation status using endoglycosidase H sensitivity

• Secretory pathway perturbation: Treat cells with Brefeldin A or Monensin and monitor effects on ADGRA2 localization

• Interactome analysis: Use co-immunoprecipitation with ADGRA2 antibodies followed by mass spectrometry to identify trafficking partners

This experimental approach would reveal whether the LRR domain directly interacts with trafficking machinery or indirectly affects ADGRA2 folding and quality control .

How can proteolytic processing of ADGRA2 be studied using domain-specific antibodies?

To investigate ADGRA2 proteolytic processing:

• Domain-specific antibody selection: Utilize antibodies that recognize:

  • N-terminal extracellular domain (pre-cleavage)

  • C-terminal seven-transmembrane domain (post-cleavage)

  • The GPS motif region (cleavage site)

• Processing detection methods:

  • Western blotting: Identify full-length and cleaved fragments by size

  • Pulse-chase experiments: Track conversion of full-length to processed forms

  • Surface biotinylation: Distinguish cell surface vs. intracellular processing

• Protease identification approach:

  • Protease inhibitor panels: Use broad and specific inhibitors (e.g., for MMPs, thrombin)

  • Site-directed mutagenesis: Generate cleavage-resistant ADGRA2 mutants

  • In vitro cleavage assays: Incubate purified ADGRA2 with candidate proteases

• Functional consequences assessment:

  • Co-immunoprecipitation: Determine if cleaved subunits remain associated

  • Proximity ligation assays: Visualize associations between subunits

  • Signaling assays: Measure Wnt pathway activation with reporters (TOPFlash)

Research has shown that ADGRA2 is proteolytically cleaved into two subunits (extracellular and seven-transmembrane) and is processed by thrombin (F2), MMP1, and less efficiently by MMP9. The presence of protein disulfide-isomerase P4HB at the cell surface is required for shedding of the extracellular subunit, suggesting disulfide bond linkage between subunits .

What strategies can resolve non-specific binding issues with ADGRA2 antibodies?

To minimize non-specific binding when using ADGRA2 antibodies:

• Blocking optimization:

  • Test different blocking agents (BSA, normal serum, commercial blockers)

  • Increase blocking time (2-16 hours)

  • Use species-specific blockers matched to secondary antibody

• Antibody dilution optimization:

  • Perform titration experiments with dilution series

  • Use higher dilutions than manufacturer recommendations initially

• Incubation conditions:

  • Reduce primary antibody incubation temperature (4°C instead of room temperature)

  • Extend incubation time with more dilute antibody (overnight at 4°C)

• Washing protocol enhancement:

  • Increase number of wash steps (5-6 times instead of 3)

  • Extend wash durations (10-15 minutes per wash)

  • Add detergent (0.1-0.3% Tween-20) to wash buffers

• Secondary antibody considerations:

  • Use highly cross-adsorbed secondary antibodies

  • Reduce secondary antibody concentration

  • Consider signal amplification systems for specific signal enhancement

• Sample preparation improvements:

  • Optimize fixation protocol (test paraformaldehyde, methanol, or acetone)

  • Adjust permeabilization conditions (type and concentration of detergent)

  • Include antigen retrieval steps for tissue sections

• Validation with controls:

  • Include secondary-only controls

  • Use pre-immune serum controls

  • Include blocking peptide competition assays

These approaches should be systematically tested to determine the optimal conditions for minimizing background while maintaining specific ADGRA2 detection .

How does choice of fixation method affect ADGRA2 epitope detection?

The choice of fixation method significantly impacts ADGRA2 epitope detection:

• Paraformaldehyde (PFA) fixation:

  • Preserves most ADGRA2 epitopes, especially those in the extracellular domain

  • Recommended concentration: 2-4% for 10-20 minutes

  • Maintains subcellular localization patterns

  • May require light permeabilization for intracellular epitopes

  • Compatible with most ADGRA2 antibodies targeting extracellular domains

• Methanol fixation:

  • Better for exposing some intracellular epitopes

  • Simultaneously fixes and permeabilizes

  • May denature some conformational epitopes in ADGRA2's extracellular domains

  • Can disrupt membrane localization patterns

  • Test with antibodies recognizing linear epitopes

• Acetone fixation:

  • Rapid fixation with good preservation of antigenicity

  • Better for some cytoskeletal associations

  • May extract membrane lipids, affecting ADGRA2 localization

  • Test for short durations (5-10 minutes)

• Glutaraldehyde fixation:

  • Strong crosslinking may mask ADGRA2 epitopes

  • Generally not recommended unless combined with PFA at low percentage

  • Requires more aggressive antigen retrieval

• Epitope-specific considerations:

  • LRR domain: Generally well-preserved with PFA

  • Transmembrane domains: May require specialized fixation-permeabilization

  • GPS cleavage site: Sensitive to fixation conditions

  • C-terminal epitopes: Often require good permeabilization

Researchers should conduct comparative fixation studies with their specific ADGRA2 antibody to determine optimal conditions for their experimental system .

What are the optimal storage conditions to maintain ADGRA2 antibody functionality?

For optimal ADGRA2 antibody preservation and functionality:

• Short-term storage (up to 1 month):

  • Store at 4°C

  • Add preservative (0.02% sodium azide)

  • Avoid repeated freeze-thaw cycles

• Long-term storage (months to years):

  • Store at -20°C or preferably -80°C

  • Aliquot to avoid repeated freeze-thaw cycles

  • Use glycerol (25-50%) as cryoprotectant

• Formulation considerations:

  • PBS buffer with 50% glycerol provides stability

  • Addition of 0.5% BSA protects antibody during freeze-thaw

  • Maintain pH between 7.2-7.4

• Handling precautions:

  • Avoid contamination (use sterile technique)

  • Centrifuge briefly before opening to collect solution

  • Allow to equilibrate to room temperature before use

  • Return to cold storage promptly after use

• Stability monitoring:

  • Periodically test antibody function with positive controls

  • Monitor for visible precipitation or turbidity

  • Document performance over time with standardized samples

Following these guidelines will help maintain ADGRA2 antibody functionality for up to 1 year at -20°C or longer at -80°C .

How can researchers distinguish between different ADGRA2 isoforms when using antibodies?

To differentiate between ADGRA2 isoforms:

• Antibody selection strategy:

  • Use epitope-specific antibodies targeting unique regions of each isoform

  • Employ antibodies recognizing common domains as pan-ADGRA2 detectors

  • Select antibodies raised against synthetic peptides from isoform-specific sequences

• Detection techniques:

  • Western blotting: Resolve isoforms by molecular weight differences

    • Full-length ADGRA2: ~142 kDa (calculated)

    • Proteolytically processed forms: Extracellular and seven-transmembrane fragments

    • Variant isoforms: Different migration patterns based on domain composition

  • RT-PCR: Design primers flanking alternative splicing junctions

  • Immunoprecipitation followed by mass spectrometry: Identify isoform-specific peptides

• Expression system controls:

  • Generate recombinant constructs expressing specific isoforms

  • Use as positive controls for antibody validation

  • Create knockout/knockdown systems to confirm specificity

• Analytical considerations:

  • Use high-resolution gel systems (6-8% acrylamide) to separate high MW isoforms

  • Employ gradient gels (4-15%) to simultaneously visualize full-length and cleaved forms

  • Compare reducing vs. non-reducing conditions to assess disulfide-linked fragments

• Post-translational modification assessment:

  • Glycosylation analysis: Use endoglycosidases to determine contribution to size differences

  • Phosphorylation: Use phosphatase treatment or phospho-specific antibodies

  • Proteolytic processing: Analyze N-terminal and C-terminal fragments separately

This multi-faceted approach enables comprehensive characterization of ADGRA2 isoforms in experimental systems .

What methods can discriminate between membrane-localized and intracellular pools of ADGRA2?

To differentiate between membrane and intracellular ADGRA2 pools:

• Subcellular fractionation approaches:

  • Differential centrifugation to separate membrane, cytosolic, and organelle fractions

  • Density gradient centrifugation for higher resolution separation

  • Verification with compartment markers (Na+/K+ ATPase for plasma membrane, AKT for cytosol, calnexin for ER)

• Surface protein-specific techniques:

  • Cell surface biotinylation: Label only exposed proteins, then immunoprecipitate ADGRA2

  • Surface trypsinization: Cleave extracellular domains, then compare intact vs. cleaved

  • Antibody feeding assays: Apply antibodies to live cells to label only surface proteins

• Microscopy-based methods:

  • Confocal microscopy with plasma membrane markers

  • Differential permeabilization protocols:

    • No permeabilization: Detect only surface ADGRA2

    • Mild detergent (0.01% saponin): Reveal some intracellular pools

    • Complete permeabilization (0.1% Triton X-100): Visualize all ADGRA2

  • Total internal reflection fluorescence (TIRF) microscopy: Focus only on membrane-proximal proteins

• Flow cytometry approaches:

  • Live-cell staining with antibodies against extracellular domains

  • Fixed/permeabilized cell staining for total ADGRA2

  • Ratio analysis to determine surface-to-total distribution

Studies have demonstrated that the LRR domain of ADGRA2 is critical for its progression through the secretory pathway. Deletion variants lacking individual LRR repeats (ΔLRR1-4) or all repeats (ΔLRR) show ER retention, while variants lacking other domains (ΔIg-like, ΔHRM, ΔGAIN) reach the plasma membrane similar to wild-type ADGRA2 .

How can researchers analyze the kinetics of ADGRA2-RECK complex formation in developing vasculature?

To analyze ADGRA2-RECK complex formation kinetics in developing vasculature:

• Temporal expression profiling:

  • Collect tissue samples at defined developmental timepoints

  • Perform Western blot analysis for ADGRA2 and RECK expression levels

  • Quantify protein levels normalized to appropriate housekeeping controls

• In situ interaction visualization:

  • Proximity ligation assay (PLA) at sequential developmental stages

  • Dual immunofluorescence with ADGRA2 and RECK antibodies

  • Quantify co-localization coefficients (Pearson's, Mander's) over time

• Biochemical interaction kinetics:

  • Co-immunoprecipitation at different developmental timepoints

  • Use ADGRA2 antibodies to pull down complexes and probe for RECK

  • Quantify interaction efficiency (RECK/ADGRA2 ratio) across development

• Real-time complex formation analysis:

  • Live imaging with fluorescently tagged ADGRA2 and RECK in endothelial cells

  • FRET or BiFC assays to detect protein-protein interactions

  • Track complex formation in response to Wnt7 stimulation

• Functional consequence assessment:

  • Analyze β-catenin nuclear translocation as readout of Wnt signaling

  • Monitor endothelial cell behaviors (sprouting, migration) correlated with complex formation

  • Assess vascular permeability at different developmental stages

• Domain-specific contribution analysis:

  • Use domain deletion variants of ADGRA2

  • Determine how LRR domain affects RECK binding kinetics

  • Compare ER-retained vs. surface-localized ADGRA2 variants

By implementing these systematic approaches, researchers can gain comprehensive insights into the spatial, temporal, and functional dynamics of ADGRA2-RECK interactions during vascular development.

How can ADGRA2 antibodies be utilized in investigating neurovascular unit development?

For neurovascular unit (NVU) development studies using ADGRA2 antibodies:

• Cellular component analysis:

  • Multiple immunofluorescence labeling of NVU components:

    • ADGRA2 for endothelial cells

    • NeuN/MAP2 for neurons

    • GFAP for astrocytes

    • IBA1 for microglia

    • PDGFRβ for pericytes

  • Confocal/super-resolution microscopy for spatial relationships

  • Quantitative analysis of cell-cell contact points

• Developmental timeline investigation:

  • Systematic immunohistochemistry across embryonic to postnatal stages

  • Correlation of ADGRA2 expression patterns with BBB maturation markers

  • Assessment of NVU assembly sequence with ADGRA2 as reference point

• Cell-specific deletion models:

  • Generate conditional ADGRA2 knockouts in specific cell types

  • Use antibodies to assess compensatory changes in other NVU components

  • Evaluate structural and functional consequences on NVU development

• Molecular interaction networks:

  • Immunoprecipitation with ADGRA2 antibodies followed by proteomic analysis

  • Proximity ligation assays to detect interactions with other NVU proteins

  • Co-culture experiments to assess ADGRA2's role in cell-cell communication

• Functional barrier assessment:

  • Correlate ADGRA2 expression/localization with tight junction formation

  • Track development of transport systems (glucose transporters, efflux pumps)

  • Measure barrier integrity (tracer studies) relative to ADGRA2 expression

• Pathological model applications:

  • Analyze ADGRA2 expression in developmental disorders affecting the NVU

  • Assess vascular malformations for ADGRA2 distribution abnormalities

  • Study injury models (hypoxia-ischemia) for ADGRA2 response patterns

This comprehensive approach would leverage ADGRA2 antibodies to elucidate the protein's role in coordinating neurovascular development and maturation .

What methodological approaches can determine if post-translational modifications affect ADGRA2 antibody epitope recognition?

To assess how post-translational modifications (PTMs) affect ADGRA2 antibody epitope recognition:

• PTM site identification:

  • Bioinformatic prediction of potential PTM sites (phosphorylation, glycosylation, etc.)

  • Mass spectrometry analysis of purified ADGRA2 to map actual PTMs

  • Compare epitope regions with known/predicted PTM sites

• Enzyme treatment experiments:

  • Phosphatase treatment to remove phosphorylation

  • Glycosidase panel (PNGase F, Endo H, O-glycosidase) for deglycosylation

  • Compare antibody detection before and after enzymatic treatment

• Site-directed mutagenesis:

  • Generate ADGRA2 constructs with mutations at PTM sites

  • Express in cellular systems and assess antibody recognition

  • Compare wild-type vs. PTM-deficient variants

• Differential extraction methods:

  • Use buffers optimized for preserving specific PTMs

  • Compare antibody detection efficiency across extraction protocols

  • Control with PTM-specific antibodies (phospho-specific, glyco-specific)

• Sequential immunoprecipitation:

  • First IP with PTM-specific antibodies

  • Second IP with ADGRA2-specific antibodies

  • Analyze overlap and distinct populations

• Epitope mapping experiments:

  • Create peptide arrays with and without specific PTMs

  • Test antibody binding to modified and unmodified peptides

  • Determine precise effect of modifications on epitope recognition

Research has shown that ADGRA2 undergoes glycosylation and proteolytic cleavage into extracellular and seven-transmembrane subunits. The protein is cleaved by thrombin (F2), MMP1, and less efficiently by MMP9. Additionally, the presence of protein disulfide-isomerase P4HB at the cell surface is required for shedding of the extracellular subunit, suggesting disulfide linkage between subunits .

What bioinformatic tools can help design experiments to validate ADGRA2 antibody cross-reactivity with orthologs?

Bioinformatic tools and experimental strategies for validating ADGRA2 antibody cross-reactivity with orthologs:

• Sequence analysis tools:

  • Multiple sequence alignment (Clustal Omega, MUSCLE) to compare ADGRA2 across species

  • Epitope region conservation analysis (JalView, BioEdit)

  • Protein BLAST to identify potential cross-reactive proteins

  • Visualization of alignment with epitope highlighting (ESPript, WebLogo)

• Epitope prediction resources:

  • BepiPred, DiscoTope for B-cell epitope prediction

  • IEDB Analysis Resource for antigenic determinants

  • Structural mapping of epitopes using PyMOL or UCSF Chimera

  • Conservation scoring of epitope regions (ConSurf)

• Experimental design tools:

  • Primer design software for amplifying ortholog genes (Primer3, NCBI Primer-BLAST)

  • Codon optimization tools for heterologous expression (IDT, GeneArt)

  • Plasmid design software for expression constructs (SnapGene, Vector NTI)

• Cross-reactivity validation approach:

  • Express recombinant ADGRA2 orthologs from multiple species

  • Create epitope-focused peptide arrays across species

  • Design Western blot experiments with tissue samples from multiple species

  • Develop immunohistochemistry protocols with appropriate controls

• Species-specific validation pipeline:

  • Compare commercially available ADGRA2 antibodies with reported cross-reactivity:

    • Human and mouse reactivity is common

    • Some antibodies show reactivity to rat and gorilla

    • Zebrafish-specific antibodies are available for evolutionary studies

  • Validate using both overexpression and knockdown approaches

  • Confirm with tissue samples known to express ADGRA2

• Data integration platforms:

  • Use UniProt, Ensembl, and NCBI for ortholog information

  • Leverage Antibodypedia or Biocompare for existing cross-reactivity data

  • Document findings in antibody validation repositories