SAPK7 Antibody
Description
SAPK7 Functional Overview
SAPK7 (SnRK2 family member) is implicated in:
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Phosphorylation events: Critical for plant-virus interactions, such as phosphorylating the Chinese wheat mosaic virus (CWMV) cysteine-rich protein (CRP) at residues S162/S165, facilitating viral evasion of plant immunity .
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Stress signaling: SnRK2 kinases typically mediate responses to abiotic stresses (e.g., drought, salinity) .
Antibody Applications in SAPK7 Research
Although SAPK7-specific antibodies are not explicitly reported, analogous antibody-based techniques could be applied:
3.1. Phosphorylation Mechanism
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Kinase activity: TaSAPK7 phosphorylates CWMV CRP in a dose-dependent manner, with phosphorylation abolished in S162A/S165A mutants .
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Functional impact: Phosphorylated CRP suppresses plant immune responses, enhancing viral infectivity .
Table 1: SAPK7 Kinase Homologs in Wheat
| Homolog | Sequence Identity | Genomic Location |
|---|---|---|
| TraesCS2A02G303900.1 | 99.91% | Chromosome 2A |
| TraesCS2B02G320500.1 | 99.91% | Chromosome 2B |
| TraesCS2D02G302500.1 | 99.91% | Chromosome 2D |
Table 2: Antibody Performance Metrics (Hypothetical)
| Parameter | ELISA | Western Blot | Flow Cytometry |
|---|---|---|---|
| Sensitivity | 1–10 ng/mL | 0.1–1 μg total protein | 10³–10⁴ cells/sample |
| Target | Phosphorylated CRP | SAPK7 (~40–50 kDa) | Intracellular SAPK7 |
| Citation |
Future Directions
Product Specs
Composition: 50% Glycerol, 0.01M PBS, pH 7.4
Target Background
Q&A
What is the functional significance of SAPK7 phosphorylation in plant-virus interactions?
SAPK7 phosphorylates CWMV CRP at residues S162/S165, enabling the virus to evade wheat immunity by altering host RNA-binding protein interactions. Methodologically, this is demonstrated through:
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Yeast two-hybrid (Y2H) screens to identify SAPK7-CRP interactions (Fig. 3A) .
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Bimolecular fluorescence complementation (BiFC) and luciferase (LUC) assays to confirm kinase-substrate binding in planta (Fig. 3B–C) .
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In vitro kinase assays using [γ-32P] ATP to quantify phosphorylation (Fig. 3D–F) .
These approaches validate SAPK7 as the primary kinase responsible for CRP modification, with phosphorylation-mimetic mutants (CRP S162/165D) showing enhanced viral pathogenicity.
How do researchers detect SAPK7-mediated phosphorylation events in plant tissues?
A validated protocol involves:
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Co-immunoprecipitation (Co-IP) using anti-SAPK7 antibodies to isolate kinase complexes from wheat or Nicotiana benthamiana extracts.
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Phosphorylation-specific antibodies targeting CRP S162/S165, though these require validation via:
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Site-directed mutagenesis (e.g., S→A or S→D substitutions).
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Mass spectrometry to confirm phosphorylation sites.
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Radiolabeled ATP assays to measure kinase activity (Fig. 3D) .
How should researchers resolve contradictions in phosphorylation assays using phosphomimetic mutants?
The unexpected phosphorylation of CRP S162/165D in vitro (Fig. 3F) highlights two hypotheses requiring further testing:
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Secondary phosphorylation sites: Mutations at S162/S165 may expose cryptic sites (e.g., T160 or Y167) that become accessible for SAPK7.
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Conformational dependency: Phosphorylation at S162/S165 may induce structural changes that facilitate SAPK7 activity at other residues.
Methodological recommendations:
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Conduct alanine scanning mutagenesis across the CRP sequence.
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Use phosphoproteomics to map all SAPK7-dependent sites under wild-type and mutant conditions.
What strategies optimize SAPK7 antibody specificity in co-immunoprecipitation assays?
Key considerations include:
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Epitope validation: Compare antibody performance against SAPK7 knockout lines or siRNA-treated plants.
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Cross-reactivity testing: Assess binding to homologs (e.g., SAPK6/SAPK8) using recombinant proteins.
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Buffer optimization: Include phosphatase inhibitors (e.g., NaF/β-glycerophosphate) to preserve phosphorylation states during extraction.
Table 1: Key Findings on SAPK7-CRP Phosphorylation Dynamics
How does SAPK7 phosphorylation of CRP influence host RNA-binding protein dynamics?
Phosphorylated CRP (S162/165D) binds TaUBA2C, a wheat RNA-binding protein, and inhibits its defense functions via:
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Subcellular redistribution: CRP-TaUBA2C complexes reduce nuclear speckle formation (critical for RNA processing).
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Functional impairment: Phosphorylated CRP reduces TaUBA2C’s RNA/DNA-binding activity by 60%, quantified via electrophoretic mobility shift assays (EMSAs) .
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Downstream effects: Silencing TaUBA2C increases CWMV replication, while overexpression reduces viral load by 70% .
