GRX6 Antibody
Description
Introduction to GRX6 and Its Antibody
GRX6 (Glutaredoxin-6) is a monothiol glutaredoxin in Saccharomyces cerevisiae involved in redox regulation within the endoplasmic reticulum (ER) and Golgi compartments . The GRX6 antibody is a critical tool for detecting this protein’s localization, expression, and functional roles in cellular processes such as oxidative stress response, calcium homeostasis, and protein folding .
Key Antibody Types
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Anti-HA Tag Antibodies: Used in studies where GRX6 is epitope-tagged (e.g., Grx6-HA). These antibodies enable immunofluorescence and immunoprecipitation to assess localization and protein interactions .
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Custom Polyclonal Antibodies: Generated against specific GRX6 epitopes. For example, antibodies targeting the N-terminal transmembrane domain or active-site regions (e.g., CSYS motif) have been validated via Western blot and immunocytochemistry .
Validation Metrics
Cellular Localization of GRX6
GRX6 is membrane-associated via its N-terminal transmembrane domain, localizing primarily to the ER and cis-Golgi . Key findings include:
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Subcellular Fractionation: GRX6 co-sediments with ER (Dpm1) and Golgi (Emp47) markers in sucrose gradients .
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Immunofluorescence: Punctate staining overlaps with Sed5-GFP (cis-Golgi marker) but not Sec7-GFP (trans-Golgi) .
Comparison of GRX6 and GRX7 Localization
| Feature | GRX6 | GRX7 |
|---|---|---|
| Primary Localization | ER and cis-Golgi | Predominantly cis-Golgi |
| Transmembrane Domain | Required for ER/Golgi retention | Required for Golgi retention |
| Stress Induction | Upregulated by Ca²⁺, Na⁺, peroxides | Less responsive to stressors |
Role in Redox Homeostasis
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GRX6 deglutathionylates target proteins in the ER/Golgi lumen, modulating glutathione redox balance .
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Phenotypic Defects in Δgrx6:
Calcium Regulation
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Δgrx6 mutants exhibit cytosolic calcium accumulation and reduced ER calcium levels, linking GRX6 to calcineurin pathway regulation .
Iron Binding Capacity
GRX6 binds labile iron in vivo, dependent on its active-site cysteine (C136) :
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⁵⁵Fe Assay: GRX6-HA binds ~1 pmol Fe/g cells; mutation (C136S) abolishes binding .
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Cluster Formation: Recombinant GRX6 forms Fe/S clusters in vitro, but not GRX7 .
Key Applications
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Localization Studies: Mapping GRX6 to secretory vesicles via immunofluorescence .
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Functional Analysis: Testing enzymatic activity using site-directed mutants .
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Stress Response Profiling: Quantifying UPR activation under redox stressors .
Growth Phenotypes Under Stress
| Condition | Wild-Type | Δgrx6 | Δgrx7 | Δgrx6Δgrx7 |
|---|---|---|---|---|
| H₂O₂ (1.5 mM) | Normal | Sensitive | Normal | Highly sensitive |
| FK506 (calcineurin inhibitor) | Normal | Sensitive | Normal | Sensitive |
| 37°C | Normal | Temperature-sensitive | Normal | Synthetic growth defect |
Product Specs
Target Background
Glutaredoxin 6 (GRX6) Antibody Background:
- The crystal structure of Grx6 in complex with a glutathione-coordinated [2Fe-2S] cluster has been determined (PMID: 27710937).
- Grx6 plays a critical role in intracellular calcium homeostasis. Grx6 deficiency leads to reduced ER luminal calcium and cytosolic accumulation from extracellular sources (PMID: 25355945).
- Compared to Grx1, Grx6 exhibits lower glutathione disulfide reductase activity but higher glutathione S-transferase activity (PMID: 20347849).
- Overexpression of Grx6 in *S. pombe* resulted in approximately 1.3-fold increased Grx activity during exponential growth and enhanced stress resistance (PMID: 18182845).
- Grx6 and Grx7 do not broadly participate in general oxidative protein folding in the early secretory pathway, but instead specifically counteract the oxidation of particular thiol groups in substrate proteins (PMID: 18400945).
- GRX6 is implicated in regulating the sulfhydryl oxidative state under the oxidizing conditions of early secretory pathway vesicles (PMID: 18503006).
KEGG: sce:YDL010W
STRING: 4932.YDL010W
Q&A
What experimental validation protocols establish GRX6 antibody specificity in Western blot applications?
To confirm GRX6 antibody specificity:
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Perform parallel blots with knockout cell lines or siRNA-treated samples to verify target band disappearance
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Include peptide absorption controls (pre-incubate antibody with 10x molar excess of immunizing peptide for 1 hr at 37°C)
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Validate using secondary antibody-only controls to exclude non-specific binding
Validation Data Comparison
| Control Type | Expected Outcome | Acceptable Signal Variation |
|---|---|---|
| Knockout cell lysate | Complete band absence | ≤5% background intensity |
| Peptide-blocked | ≥90% signal reduction | p<0.01 by densitometry |
| Isotype control | No bands in target MW range | 0 detectable bands |
How should researchers optimize GRX6 antibody dilution for immunohistochemistry?
Adopt a three-phase optimization protocol:
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Screening Phase: Test 1:50-1:1000 dilutions on positive/negative control tissues
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Signal Refinement: Adjust based on endogenous antigen levels (high-abundance: 1:200-1:500; low: 1:50-1:100)
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Validation: Confirm optimal dilution replicates published staining patterns from ≥2 independent studies
What methodologies resolve contradictory staining patterns in GRX6 immunofluorescence studies?
Implement a triangulation verification framework:
Step 1: Epitope Integrity Assessment
Step 2: Cross-platform Validation
Step 3: Biological Context Analysis
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Correlate staining intensity with functional assays (e.g., GnRH receptor activation assays for GRX6 targets)
How can computational models predict GRX6 antibody-antigen binding dynamics?
The AbX framework integrates three constraint modalities :
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Evolutionary Constraints
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Pre-trained protein language models (pLMs) evaluate sequence plausibility
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Output: Conservation score (0-1 scale) for each residue position
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Geometric Constraints
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SE(3)-equivariant networks model 3D paratope-epitope complementarity
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Critical parameters:
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van der Waals collision score <0.25 Å
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Electrostatic potential mismatch <15%
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Physical Constraints
Molecular dynamics simulations assess:-
Binding free energy (ΔG ≤ -10 kcal/mol)
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Dissociation half-life (t₁/₂ ≥ 1 hr)
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Performance Metrics
| Model Component | Prediction Accuracy (%) | RMSD (Å) |
|---|---|---|
| Sequence-Structure | 92.4 ± 3.1 | 1.8 |
| Affinity Prediction | 88.7 ± 2.8 | N/A |
What protocols minimize non-specific binding in GRX6 flow cytometry applications?
Adopt a four-component blocking strategy:
Solution Composition
| Component | Concentration | Function |
|---|---|---|
| Species-matched IgG | 2% w/v | Fc receptor blockade |
| Sodium Azide | 0.1% | Internalization inhibition |
| BSA (Protease-free) | 5% | Non-specific site blocking |
| Tween-20 | 0.05% | Hydrophobic interaction reduction |
Implementation Protocol
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Pre-block cells for 45 min at 4°C
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Use intracellular staining-grade fixation (4% PFA + 0.1% glutaraldehyde)
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Include fluorescence-minus-one (FMO) controls for gating validation
How do humanized antibody variants enhance GRX6 research applications?
Comparative Performance of Humanized GRX6 Variants
| Parameter | Murine G6 | Humanized G6.3 | Improvement |
|---|---|---|---|
| Binding Affinity (KD) | 12.3 nM | 6.8 nM | 1.8× |
| ADCC Activity (EC50) | 48 μg/mL | 22 μg/mL | 2.2× |
| CDC Activation | 35% lysis | 62% lysis | 1.8× |
Humanization Protocol
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CDR grafting onto human IgG1 framework
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Affinity maturation via error-prone PCR (5 cycles, 0.5% mutation rate)
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Negative selection against human serum albumin binding
What criteria establish GRX6 antibody functional validation in disease models?
Adopt the NIH Antibody Validation Tier System:
Tier 1: Genetic Confirmation
Tier 2: Orthogonal Validation
Tier 3: Functional Correlation
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Antibody blocking induces expected phenotypic changes (e.g., ≥50% reduction in GnRH-mediated cAMP production for GRX6)
How to assess GRX6 antibody species cross-reactivity?
Implement phylogenetic epitope mapping:
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Sequence Alignment
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Compare target epitope (e.g., GnRHR 297-316) across species using Clustal Omega
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Structural Modeling
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Predict cross-reactivity using ABodyBuilder2 with parameters:
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Epitope similarity score >0.75
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Steric clash score <0.3
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Experimental Validation
Methodological Recommendations
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For developmental biology studies, combine GRX6 IHC with lineage tracing using Cre-LoxP systems (≥90% recombination efficiency)
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In cancer research, validate findings using patient-derived xenograft models treated with humanized GRX6 variants
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Always include temporal controls when studying dynamic processes (e.g., neural differentiation)
