SRK2E Antibody
Description
Definition and Target Protein Overview
SRK2E Antibody detects SRK2E (SNF1-related protein kinase 2.6), a serine/threonine-protein kinase central to ABA-mediated stress responses. SRK2E, also known as OST1 (Open Stomata 1), regulates stomatal closure during drought, pathogen defense, and osmotic stress . It is a member of the SnRK2 family, which is activated by ABA or osmotic stress .
Key Features of SRK2E:
-
Function: Phosphorylates downstream targets like SLAC1 (Slow Anion Channel-Associated 1) to mediate stomatal closure and ABA-responsive gene expression .
Antibody Development and Specificity
SRK2E antibodies are generated using immunogens derived from the target protein. Examples include:
Key Research Applications
SRK2E antibodies have been instrumental in:
-
Protein-Protein Interaction Studies: Co-immunoprecipitation (Co-IP) confirmed SRK2E’s interaction with PP2C phosphatases (e.g., ABI1) and Raf-like kinases .
-
Kinase Activity Assays: In-gel phosphorylation assays revealed ABA-dependent activation of SRK2E and its inactivation by PP2C dephosphorylation .
-
Subcellular Localization: Immunofluorescence demonstrated SRK2E’s cytosolic and nuclear localization in guard cells .
-
Post-Translational Modification Analysis: Phospho-specific antibodies (e.g., Anti-Phospho-S175) identified critical phosphorylation sites in SRK2E’s activation loop .
A. Regulation by PP2C Phosphatases
-
PP2Cs (e.g., ABI1, AHG1) directly dephosphorylate SRK2E, inactivating ABA signaling .
-
Dominant PP2C mutants (e.g., abi1–1) retain the ability to bind and dephosphorylate SRK2E, leading to ABA insensitivity .
B. Phosphorylation Dynamics
-
ABA induces phosphorylation at Ser175 and other residues in SRK2E’s activation loop, which are reversed by PP2Cs .
-
Phospho-specific antibodies validated hyperactivation of SRK2E in PP2C-deficient mutants (ahg1–1, ahg3–1) .
C. Interaction with Raf-Like Kinases
-
SRK2E interacts with Raf36, a Raf-like kinase, via its N-terminal domain. This interaction requires Raf36’s full-length structure .
-
Raf36 phosphorylation by SRK2E modulates ABA-independent stress responses .
Example: Phospho-SnRK2.6-S175 pAb
| Assay | Result |
|---|---|
| Western Blot | Detects recombinant phospho-SRK2E at ~38 kDa (calculated MW) with 1:500 dilution. |
| Specificity | No cross-reactivity with non-phosphorylated SRK2E or other SnRK2 isoforms. |
Product Specs
Constituents: 50% Glycerol, 0.01M PBS, pH 7.4
Target Background
- SnRK2.6 phosphorylates AKS1 in guard cells. PMID: 28438792
- OST1 is essential for methyl jasmonate (MeJA)-induced stomatal closure, while PYR1, PYL1, PYL2 and PYL4 ABA receptors were not sufficient factors. PMID: 27354421
- BAK1 regulates ABA-induced stomatal closure in guard cells PMID: 26724418
- CHYR1 interacts with SNF1-RELATED PROTEIN KINASE2 (SnRK2) kinases and can be phosphorylated by SnRK2.6 on the Thr-178 residue. PMID: 26508764
- OST1 functions downstream of ABAR in abscisic acid receptor signaling in guard cells. Notably, ABAR protein is phosphorylated, but independently of the OST1 protein kinase. PMID: 26175350
- The role of OST1 in Yeast Elicitor-induced stomatal closure in Arabidopsis has been investigated. PMID: 25840086
- HAB1 C186 and C274 have been identified as H2O2-sensitive thiols. Oxidation of these thiols inhibits both HAB1 catalytic activity and its ability to physically associate with SnRK2.6 through the formation of intermolecular dimers PMID: 25460914
- SnRK2.6 undergoes S-nitrosylation at cysteine 137, a residue adjacent to the kinase catalytic site. PMID: 25550508
- OST1 is a critical limiting component in abscissic acid regulation of stomatal apertures, ion channels, and NADPH oxidases in Arabidopsis guard cells. PMID: 24033256
- OST1 is required for rapid stomatal closure in response to ozone, reduced air humidity, and darkness-induced stomatal regulation. PMID: 23703845
- The *atabcg22* mutation further increased the water loss of *srk2e/ost1* mutants, which were defective in ABA signaling in guard cells. PMID: 21575091
- ABI1 and OST1 represent regulatory elements for the abscissic acid-dependent activation of QUAC1-type guard cell anion currents. PMID: 23452338
- This study describes the cloning, expression, purification, crystallization, and preliminary X-ray analysis of two mutants of OST1 from *Arabidopsis thaliana*. PMID: 21393844
- Data show that OST1 phosphorylates ABF3 on multiple LXRXXpS/T preferred motifs, including T451, located within a conserved 14-3-3 binding site. PMID: 21085673
- Data provide evidence for the involvement of distinct phosphorylation mechanisms in the activation of SnRK2.6 and SnRK2.10. PMID: 20561261
- OST1 and SLAC1 are regulators of the ROS-induced rapid stomatal closure. SLAC1 is phosphorylated by OST1. PMID: 20128877
- SRK2E mediates hormonal and metabolic regulation of plant growth and development, and is implicated in the regulation of metabolic homeostasis. PMID: 20200070
- Results provide evidence that PP2Cs are directly involved in the ABA-dependent activation of OST1. PMID: 19855047
- Findings suggest that negative regulation of KAT1 activity, required for stomatal closure, likely occurs through the phosphorylation of KAT1 Thr306 by the stress-activated endogenous SnRK2.6 protein kinase. PMID: 19785574
- SRK2E participates in the stomatal response to reduced relative humidity. PMID: 16682349
- The identification of key residues involved in regulating OST1 activity is discussed. PMID: 16766677
- The function of UBA2a is independent of OST1 phosphorylation. PMID: 16828085
