DAPK3 (Ab-265) Antibody

What is DAPK3 and what cellular functions does it regulate?

DAPK3 (Death-Associated Protein Kinase 3), also known as ZIP kinase, ZIPK, or Dlk, is a serine/threonine kinase that plays significant roles in multiple cellular processes. It functions in the regulation of apoptosis, autophagy, transcription, translation, actin cytoskeleton reorganization, cell motility, smooth muscle contraction, and mitosis, particularly cytokinesis. DAPK3 regulates both type I apoptotic (caspase-dependent) and type II autophagic (caspase-independent) cell death signals, depending on the cellular context. In smooth muscle cells, it regulates myosin either directly by phosphorylating MYL12B and MYL9 or indirectly through inhibition of smooth muscle myosin phosphatase via phosphorylation of PPP1R12A, enhancing muscle responsiveness to Ca²⁺ and promoting contractile function .

What epitope does the DAPK3 (Ab-265) antibody recognize?

The DAPK3 (Ab-265) antibody specifically recognizes the region surrounding the phosphorylation site at threonine 265 of the human DAPK3 protein. For phospho-specific antibodies, the immunogen is typically a synthesized phosphopeptide derived from human DAPK3 with the sequence containing phosphorylated Thr265 (R-M-T(p)-I-A) . The phospho-specific antibodies (like those in search results 1 and 2) detect DAPK3 only when phosphorylated at Thr265, while non-phospho antibodies (like in search result 3) recognize the same region regardless of phosphorylation status .

What is the difference between host species options for DAPK3 antibodies?

DAPK3 antibodies are predominantly available as rabbit polyclonal antibodies, as seen in all the search results. Rabbit-derived antibodies often provide high sensitivity and specificity for phosphorylation-specific epitopes. While mouse monoclonal options exist for certain DAPK3 epitopes (mentioned in search result 2 for other regions of the protein), the Thr265 phospho-specific antibodies appear to be primarily available as rabbit polyclonals. The polyclonal nature provides the advantage of recognizing multiple epitopes around the phosphorylation site, potentially increasing detection sensitivity, though with possible variation between lots compared to monoclonal antibodies .

What species reactivity is confirmed for DAPK3 (Ab-265) antibody?

The species reactivity of DAPK3 (Ab-265) antibodies varies slightly depending on the manufacturer. Based on the search results, these antibodies generally react with human and mouse samples, with some also confirmed for rat samples. Specifically, the antibody in search result 1 reacts with human, mouse, and rat samples . The antibody in search result 2 shows confirmed reactivity with mouse and rat, plus predicted reactivity with human, dog, cow, pig, and horse . The antibody in search result 3 specifically mentions reactivity with human and mouse samples . This cross-reactivity reflects the conservation of the Thr265 phosphorylation site and surrounding amino acids across mammalian species.

What applications are validated for DAPK3 (Ab-265) antibody?

The DAPK3 (Ab-265) antibody has been validated for multiple experimental applications. Western blotting (WB) is consistently mentioned across all antibody products as a primary application, allowing researchers to detect and quantify phosphorylated DAPK3 at Thr265 in cell and tissue lysates. ELISA applications are also universally supported, including colorimetric cell-based ELISA systems for detecting DAPK3 in intact cells . Immunofluorescence (IF) applications are validated for both cultured cells (IF/ICC) and tissue sections (paraffin-embedded and frozen sections), enabling visualization of the subcellular localization of phosphorylated DAPK3 . Immunohistochemistry (IHC) is also supported by several antibody products, allowing detection in tissue samples .

What are the recommended dilutions for DAPK3 (Ab-265) antibody in different applications?

The recommended dilutions vary by application and manufacturer, but general guidelines from the search results include:

• Western Blotting (WB): 1:500-1:1000

• Immunofluorescence (IF): 1:100-1:500

• ELISA: 1:5000

These dilutions serve as starting points and may require optimization for specific experimental conditions, sample types, and detection methods. When using cell-based ELISA formats, the specific protocols provided with the kit should be followed as described in search result 4, which outlines a colorimetric cell-based ELISA system for DAPK3 .

How should samples be prepared for optimal detection of phosphorylated DAPK3?

For optimal detection of phosphorylated DAPK3 at Thr265, samples should be prepared with phosphatase inhibitors to preserve the phosphorylation state. While specific preparation methods aren't detailed in the search results, standard protocols for phospho-proteins include:

• Cell lysis in buffers containing phosphatase inhibitor cocktails (e.g., sodium fluoride, sodium orthovanadate, β-glycerophosphate)

• Maintaining cold temperatures throughout sample preparation

• Adding protease inhibitors to prevent degradation

• Minimizing freeze-thaw cycles

For immunofluorescence or immunohistochemistry, fixation methods should preserve phospho-epitopes, with paraformaldehyde fixation often preferred over methanol for phosphorylated proteins. The antibody can be used for both cultured cells and paraffin-embedded tissue sections as indicated in search result 2 .

What controls should be included when using DAPK3 (Ab-265) antibody?

When working with phospho-specific antibodies like DAPK3 (Ab-265), several controls should be included:

• Positive control: Lysates from cells with known DAPK3 Thr265 phosphorylation (e.g., cells treated with appropriate stimuli)

• Negative control: Samples treated with lambda phosphatase to remove phosphorylation

• Isotype control: Using appropriate isotype control antibodies such as Rabbit IgG (A82272) or Rabbit IgG (A17360) mentioned in search result 1

• Secondary antibody controls: Appropriate secondary antibodies for the host species, such as Goat Anti-Rabbit IgG H&L Antibody conjugated with various detection systems (AP, Biotin, FITC, HRP) as mentioned in search result 1

• Loading controls: For western blotting, include antibodies against total DAPK3 or housekeeping proteins

These controls help validate specificity and rule out false positive results.

What are common causes of high background when using DAPK3 (Ab-265) antibody?

High background when using DAPK3 (Ab-265) antibody can result from several factors:

• Excessive antibody concentration: Using higher than recommended dilutions can increase non-specific binding. Start with the recommended dilutions (WB: 1:500-1:1000, IF: 1:100-1:500, ELISA: 1:5000) and optimize if necessary .

• Insufficient blocking: Ensure thorough blocking with appropriate blocking buffers containing BSA or normal serum.

• Inadequate washing: Increase the number and duration of wash steps with appropriate buffers.

• Cross-reactivity: The antibody may cross-react with similar phospho-epitopes in other proteins.

• Sample preparation issues: High background can result from inadequate fixation, over-fixation, or sample degradation.

For immunofluorescence applications, autofluorescence can be reduced using specific quenching reagents, and for IHC applications, endogenous peroxidase activity should be quenched if using HRP-conjugated detection systems.

How can specificity of DAPK3 (Ab-265) antibody be validated?

Validating the specificity of DAPK3 (Ab-265) antibody can be approached through several methods:

• Peptide competition assay: Pre-incubation of the antibody with the immunizing phosphopeptide should block specific binding.

• Phosphatase treatment: Treatment of samples with lambda phosphatase should eliminate signal from phospho-specific antibodies.

• DAPK3 knockdown/knockout: Genetic approaches to reduce or eliminate DAPK3 expression should correspondingly reduce antibody signal.

• Induction experiments: Stimulating cells with treatments known to increase Thr265 phosphorylation should increase signal intensity.

• Western blot molecular weight verification: The antibody should detect a band at the expected molecular weight of DAPK3 (approximately 52 kDa) .

These validation approaches help confirm that the observed signals are specifically due to phosphorylated DAPK3 rather than non-specific binding.

What storage conditions are optimal for maintaining DAPK3 (Ab-265) antibody activity?

To maintain optimal activity of DAPK3 (Ab-265) antibody, proper storage is essential:

• Upon receipt, store the antibody at -20°C or -80°C as recommended in search result 3 .

• Avoid repeated freeze-thaw cycles which can degrade antibody performance.

• For frequent use, consider aliquoting the antibody into smaller volumes before freezing.

• The antibody is typically supplied in a stabilizing buffer containing glycerol (50%), phosphate-buffered saline without Mg²⁺ and Ca²⁺, pH 7.4, NaCl (150mM), and sodium azide (0.02%) as indicated in search results 1 and 3 .

When working with the antibody, maintain cold chain practices, keeping it on ice when in use and returning to appropriate storage promptly after use.

How can I optimize antibody concentration for immunofluorescence studies?

Optimizing DAPK3 (Ab-265) antibody concentration for immunofluorescence requires a systematic approach:

• Begin with the manufacturer's recommended dilution range (1:100-1:500 for IF applications) .

• Perform a dilution series experiment (e.g., 1:50, 1:100, 1:200, 1:500, 1:1000) using positive control samples.

• Evaluate signal-to-noise ratio, not just signal intensity.

• Adjust incubation conditions (time, temperature) if necessary.

• Optimize fixation and permeabilization protocols for phospho-epitope preservation.

• Consider signal amplification systems for low-abundance targets.

• Include appropriate controls at each dilution to distinguish specific from non-specific staining.

The optimal concentration provides clear specific staining with minimal background and preserves the ability to detect differences between experimental conditions.

How can DAPK3 (Ab-265) antibody be used to study the role of DAPK3 in apoptotic vs. autophagic cell death?

DAPK3 regulates both type I (apoptotic) and type II (autophagic) cell death pathways, making the phospho-Thr265 antibody valuable for investigating these distinct mechanisms. To study these pathways:

• Induce apoptosis and autophagy using appropriate stimuli in parallel experiments.

• Monitor DAPK3 Thr265 phosphorylation status using the antibody via western blotting or immunofluorescence.

• Correlate phosphorylation patterns with markers of apoptosis (e.g., cleaved caspases, PARP cleavage) and autophagy (e.g., LC3-II formation, p62 degradation).

• Use pharmacological inhibitors of each pathway to determine if DAPK3 phosphorylation is cause or consequence.

• Implement time-course experiments to track phosphorylation dynamics during the progression of each death pathway.

• Combine with total DAPK3 antibodies to calculate phosphorylation ratios.

This approach can reveal whether Thr265 phosphorylation differs between apoptotic and autophagic cell death contexts, providing insights into pathway-specific regulation mechanisms .

What approaches can be used to study DAPK3 phosphorylation dynamics in response to cellular stress?

Studying DAPK3 phosphorylation dynamics in response to stress requires temporal and spatial monitoring approaches:

• Time-course experiments: Treat cells with stressors (oxidative stress, nutrient deprivation, cytokines) and collect samples at multiple timepoints for western blot analysis using the phospho-Thr265 antibody.

• Live-cell imaging: Combine the antibody with proximity ligation assays or FRET-based reporters to monitor phosphorylation in real-time (for fixed timepoints).

• Stimulus dose-response: Vary the intensity of stress stimuli to determine phosphorylation thresholds.

• Pharmacological interventions: Use kinase and phosphatase inhibitors to manipulate phosphorylation dynamics.

• Subcellular fractionation: Determine if phosphorylation affects DAPK3 localization between nuclear and cytoplasmic compartments.

• Colorimetric cell-based ELISA: Utilize the approach described in search result 4 for high-throughput screening of multiple conditions .

These approaches can reveal the kinetics, localization, and threshold requirements for DAPK3 phosphorylation under various stress conditions.

How can DAPK3 (Ab-265) antibody be integrated into multiplexed immunoassays?

Integrating DAPK3 (Ab-265) antibody into multiplexed immunoassays allows simultaneous detection of multiple targets and provides context for phosphorylation events:

• For immunofluorescence/IHC:

  • Use primary antibodies from different host species

  • Employ spectrally distinct fluorophores for secondary antibodies

  • Implement sequential staining protocols if using multiple rabbit antibodies

  • Use tyramide signal amplification for weak signals

• For western blotting:

  • Use fluorescent secondary antibodies with different emission spectra

  • Implement sequential stripping and reprobing protocols

  • Utilize specific lane markers and digital imaging systems

• For bead-based multiplexing:

  • Conjugate antibodies to spectrally distinct beads

  • Develop assay conditions that maintain specificity in multiplexed format

• For cell-based ELISA:

  • Develop normalization strategies using housekeeping proteins

  • Calculate phospho/total protein ratios

These approaches allow researchers to correlate DAPK3 phosphorylation with pathway components, phenotypic outcomes, and other post-translational modifications in the same sample.

What strategies can be employed to quantitatively compare DAPK3 phosphorylation levels across different experimental conditions?

Quantitative comparison of DAPK3 phosphorylation requires rigorous approaches:

• Western blot densitometry:

  • Normalize phospho-DAPK3 signal to total DAPK3 or loading controls

  • Ensure exposure within linear range of detection

  • Include standard curves of recombinant phospho-proteins

• Cell-based ELISA quantification:

  • Follow the colorimetric cell-based ELISA protocol in search result 4

  • Normalize to cell number using parallel wells with cell-counting dyes

  • Generate standard curves with known quantities of phosphorylated DAPK3

• Image analysis for IF/IHC:

  • Use identical acquisition settings across all samples

  • Quantify fluorescence intensity per cell or per defined region

  • Employ automated unbiased image analysis algorithms

• Flow cytometry:

  • Develop fixation and permeabilization protocols compatible with phospho-epitopes

  • Gate on relevant cell populations

  • Calculate mean fluorescence intensity ratios

• Statistical analysis:

  • Apply appropriate statistical tests based on data distribution

  • Account for technical and biological replicates

  • Consider multivariate analysis for complex experimental designs

These quantitative approaches enable robust comparison of phosphorylation levels, revealing subtle regulatory effects that might be missed by qualitative assessment alone.