MAP3K5 (Ab-966) Antibody

What is MAP3K5 (Ab-966) Antibody and what epitope does it recognize?

MAP3K5 (Ab-966) antibody is a rabbit polyclonal antibody specifically designed to recognize the phosphorylation site at Serine 966 of human Apoptosis Signal-regulating Kinase 1 (ASK1), also known as Mitogen-activated protein kinase kinase kinase 5 (MAP3K5). The antibody is generated using a synthesized peptide derived from the region surrounding amino acids 964-968 (S-I-S-L-P) of human ASK1 .

The epitope recognition is specific to the phosphorylated form of this serine residue, making this antibody particularly useful for studying the regulatory mechanisms of ASK1 through this specific post-translational modification.

What is the functional significance of MAP3K5/ASK1 in cellular signaling?

MAP3K5/ASK1 functions as an essential component of the MAP kinase signal transduction cascade. It plays crucial roles in:

• Mediating cellular responses to environmental changes

• Signal transduction for cell fate determination including differentiation and survival

• Apoptosis signal transduction through mitochondria-dependent caspase activation

• Innate immune response essential for host defense against pathogens

• Stress response signaling, particularly oxidative stress

• Receptor-mediated inflammatory signal transduction (e.g., TNF, LPS)

When activated, MAP3K5/ASK1 functions as an upstream activator of MKK/JNK and p38 MAPK signaling cascades by phosphorylating and activating several MAP kinase kinases including MAP2K4/SEK1, MAP2K3/MKK3, MAP2K6/MKK6, and MAP2K7/MKK7 .

What applications has the MAP3K5 (Ab-966) Antibody been validated for?

According to multiple sources, the MAP3K5 (Ab-966) antibody has been validated for the following applications:

The antibody has been specifically verified in Western blotting applications using 293 cell lysates .

What is the species reactivity profile of the MAP3K5 (Ab-966) Antibody?

The MAP3K5 (Ab-966) antibody has been confirmed to react with:

• Human

• Mouse

• Rat

This cross-species reactivity makes it valuable for comparative studies across different model systems .

What is the proper storage and handling protocol for MAP3K5 (Ab-966) Antibody?

For optimal antibody performance and longevity:

• Store at -20°C or -80°C upon receipt for long-term storage

• For frequent use and short-term storage (up to one month), the antibody can be kept at 4°C

• Avoid repeated freeze-thaw cycles

• The antibody is typically supplied in phosphate buffered saline (without Mg²⁺ and Ca²⁺), pH 7.4, containing 150mM NaCl, 0.02% sodium azide, and 50% glycerol

• Most formulations include stabilizers like 0.05% stabilizer and 0.5% protein protectant

How does phosphorylation at Ser966 mechanistically regulate MAP3K5/ASK1 activity?

Phosphorylation at Ser966 represents a key regulatory mechanism for MAP3K5/ASK1 activity. This specific modification occurs in response to various cellular stressors and affects protein-protein interactions critical for MAP3K5 function.

When Ser966 is phosphorylated, it promotes interaction with 14-3-3 proteins, which alters the subcellular distribution of MAP3K5/ASK1, restricting it to the perinuclear endoplasmic reticulum region. This sequestration effectively inhibits its kinase activity by preventing interaction with downstream targets .

In contrast to activating phosphorylation sites, Ser966 phosphorylation serves as an inhibitory modification that helps maintain MAP3K5/ASK1 in an inactive state under normal conditions. Understanding the balance between activating and inhibitory phosphorylation is crucial for interpreting experimental results.

What experimental conditions optimize detection of Ser966 phosphorylation?

To effectively detect Ser966 phosphorylation of MAP3K5/ASK1:

• Cell stimulation conditions:

  • For basal phosphorylation: Serum-starve cells for 4-6 hours before harvesting

  • For induced dephosphorylation: Treat cells with oxidative stress inducers (H₂O₂, 0.5-1 mM for 15-30 minutes)

  • For increased phosphorylation: Growth factor stimulation (serum, EGF, or insulin)

• Lysis buffer composition:

  • Include phosphatase inhibitors (sodium fluoride, sodium orthovanadate, β-glycerophosphate)

  • Add protease inhibitors cocktail

  • Use RIPA or NP-40 based buffers with 1% detergent concentration

• Sample preparation:

  • Maintain cold temperatures throughout processing

  • Process samples quickly to minimize phosphatase activity

  • Load adequate protein amount (typically 30-50 μg per lane for cell lysates)

  • For tissue samples, rapid freezing in liquid nitrogen followed by homogenization in cold lysis buffer is recommended

What are the most effective experimental controls when working with MAP3K5 (Ab-966) Antibody?

A robust experimental design when working with MAP3K5 (Ab-966) antibody should include:

Positive controls:

• 293 cell lysates (verified as a positive control in manufacturer validation)

• Heart or pancreas tissue lysates (where MAP3K5 is abundantly expressed)

• Cells treated with known activators of the ASK1 pathway

Negative controls:

• MAP3K5/ASK1 knockdown or knockout samples

• Competing peptide blocking experiments

• Samples treated with lambda phosphatase to remove phosphorylation

Specificity controls:

• Parallel blots with antibodies detecting total MAP3K5/ASK1

• Comparison with antibodies targeting other phosphorylation sites on MAP3K5/ASK1

• Dephosphorylation assays to confirm phospho-specificity

How can I troubleshoot inconsistent results when using MAP3K5 (Ab-966) Antibody in Western blotting?

When encountering inconsistent results with the MAP3K5 (Ab-966) antibody in Western blotting applications:

Always verify the expected molecular weight of MAP3K5/ASK1, which is calculated to be approximately 155 kDa .

What considerations are important for detecting MAP3K5 Ser966 phosphorylation in tissue samples?

Detecting MAP3K5 Ser966 phosphorylation in tissue samples requires special considerations:

• Tissue preparation:

  • Rapid fixation is critical to preserve phosphorylation status

  • For frozen sections, snap-freeze tissues immediately in liquid nitrogen

  • For FFPE samples, use 10% neutral buffered formalin with fixation time not exceeding 24 hours

• Antigen retrieval optimization:

  • Test both heat-mediated (citrate buffer, pH 6.0) and enzymatic methods

  • For phospho-epitopes, EDTA-based retrieval (pH 9.0) often yields better results

  • Carefully monitor retrieval times to prevent epitope destruction

• Signal amplification:

  • Consider using tyramide signal amplification for low abundance phosphoproteins

  • Polymer detection systems often provide better sensitivity than traditional ABC methods

• Tissue-specific considerations:

  • Heart and pancreas tissues show abundant expression of MAP3K5/ASK1

  • Control for endogenous peroxidase activity, particularly in blood-rich tissues

  • Include proper positive controls from the same tissue type

How can MAP3K5 (Ab-966) Antibody be effectively used in studying stress-response pathways?

To effectively use MAP3K5 (Ab-966) antibody in stress-response pathway studies:

• Experimental design for pathway analysis:

  • Time-course experiments: Monitor Ser966 phosphorylation changes over time (0, 5, 15, 30, 60 min) following stress induction

  • Dose-response studies: Vary concentrations of stress inducers to determine threshold for Ser966 phosphorylation changes

  • Combinatorial stress experiments: Apply multiple stressors to evaluate interaction effects

• Relevant stress inducers for MAP3K5/ASK1 studies:

  • Oxidative stress: H₂O₂ (0.5-1 mM), paraquat, menadione

  • Inflammatory stimuli: TNFα (10-50 ng/ml), IL-1β, LPS

  • ER stress: tunicamycin, thapsigargin

  • Genotoxic stress: UV irradiation, etoposide

• Pathway validation approaches:

  • Pharmacological inhibitors: p38 MAPK inhibitors (SB203580), JNK inhibitors (SP600125)

  • Genetic manipulation: siRNA/shRNA against upstream regulators or downstream effectors

  • Correlation with downstream markers: monitor phosphorylation of p38 MAPK and JNK in parallel

• Integration with other techniques:

  • Combine with cell viability/apoptosis assays to correlate phosphorylation with functional outcomes

  • Utilize subcellular fractionation to track MAP3K5/ASK1 localization changes upon stress

  • Employ proximity ligation assays to detect stress-induced protein interactions (e.g., with 14-3-3 proteins)

What methodological approaches can help distinguish between different phosphorylation states of MAP3K5/ASK1?

MAP3K5/ASK1 contains multiple phosphorylation sites that regulate its activity in complex ways. To distinguish between different phosphorylation states:

• Multi-antibody approach:

  • Use a panel of phospho-specific antibodies targeting different sites (S83, S966, T838, etc.)

  • Compare with total MAP3K5/ASK1 antibody to determine phosphorylation stoichiometry

  • Run parallel Western blots or use different fluorescent secondary antibodies for multiplexing

• Phosphatase treatment controls:

  • Lambda phosphatase: Removes all phosphorylation

  • Serine/threonine-specific phosphatases: Can help distinguish between phospho-serine and phospho-threonine

• Mass spectrometry-based approaches:

  • Immunoprecipitate MAP3K5/ASK1 and perform phosphopeptide mapping

  • Use MRM (Multiple Reaction Monitoring) for quantitative analysis of specific phosphorylation sites

  • Consider SILAC or TMT labeling for comparing phosphorylation across conditions

• Phospho-mimetic and phospho-dead mutants:

  • Generate S966A (phospho-dead) and S966D/E (phospho-mimetic) mutants

  • Use these mutants as controls for antibody specificity and to study functional consequences

• 2D gel electrophoresis:

  • Different phosphorylation states will appear as distinct spots

  • Can be followed by Western blotting with MAP3K5 (Ab-966) antibody

How can I integrate MAP3K5 (Ab-966) Antibody analysis with functional assays of ASK1 activity?

For comprehensive studies integrating MAP3K5 Ser966 phosphorylation status with functional activity:

• Kinase activity assays:

  • In vitro kinase assays using immunoprecipitated MAP3K5/ASK1 and substrates like MKK4 or MKK6

  • Correlation of Ser966 phosphorylation status with kinase activity

  • ATP consumption assays as surrogate measures of kinase activity

• Downstream pathway activation:

  • Monitor phosphorylation of direct MAP3K5 substrates (MAP2K4/MAP2K6)

  • Assess activation of downstream MAPKs (p38, JNK)

  • Evaluate transcriptional changes of known target genes

• Cellular outcome measurements:

  • Apoptosis assays: Annexin V/PI staining, caspase activity, TUNEL assay

  • Cell cycle analysis to detect stress-induced cell cycle arrest

  • ROS measurement to correlate oxidative stress with Ser966 phosphorylation

• Co-immunoprecipitation studies:

  • Investigate how Ser966 phosphorylation affects protein-protein interactions

  • Focus on known interaction partners like 14-3-3 proteins, TRAF2, TRAF6

  • Combine with proximity ligation assays for in situ interaction detection

• Translocation analyses:

  • Track subcellular localization changes using fractionation followed by Western blotting

  • Immunofluorescence microscopy to visualize relocalization between cytoplasm and endoplasmic reticulum

  • Live-cell imaging with fluorescently tagged MAP3K5/ASK1 to monitor dynamic changes