JUNB (Ab-259) Antibody

What is JUNB (Ab-259) Antibody and what does it specifically detect?

JUNB (Ab-259) Antibody is a rabbit polyclonal antibody that detects endogenous levels of total JunB protein. It was generated using a synthetic peptide sequence around amino acids 257-261 (P-V-S-P-I) derived from human JunB. The antibody recognizes JunB in its native form in various applications, binding specifically to this region regardless of phosphorylation status . For researchers investigating JunB function, this antibody provides a reliable tool for detecting total JunB protein levels across multiple experimental platforms.

What are the recommended applications for JUNB (Ab-259) Antibody?

JUNB (Ab-259) Antibody has been validated for multiple research applications:

• Western Blotting (WB): Recommended dilution 1:500-1:1000

• Immunohistochemistry (IHC): Recommended dilution 1:50-1:100

• ELISA: Recommended dilution 1:20000 (for some formulations)

The antibody performs best in these applications when following the validated protocols provided by manufacturers. Western blotting typically shows a characteristic band at approximately 43 kDa, while IHC demonstrates nuclear localization in cells expressing JunB .

What species does JUNB (Ab-259) Antibody react with?

While JUNB (Ab-259) Antibody was raised against human JunB epitope, cross-reactivity has been documented with multiple species:

When using this antibody in non-human systems, preliminary validation is recommended to confirm reactivity in your specific experimental context . Cross-reactivity occurs due to the high conservation of the epitope region across mammalian species.

How can JUNB (Ab-259) Antibody be used to study JunB's role in apoptosis pathways?

JUNB (Ab-259) Antibody can be used to monitor JunB protein during apoptosis studies through several approaches:

• Detection of JunB cleavage products: During apoptosis, JunB can be cleaved by caspases, generating fragments of approximately 28 kDa. Using JUNB (Ab-259) Antibody in western blot analysis of cells treated with apoptosis inducers (e.g., staurosporine) allows monitoring of this cleavage event .

• Temporal analysis: Time-course experiments with apoptosis inducers can reveal how quickly JunB is processed during programmed cell death.

• Colocalization studies: Combined with caspase activity assays or co-staining with markers of apoptosis, IHC applications can reveal the spatial relationship between JunB and apoptotic signaling components.

Research has shown that the characteristic ~43-45 kDa JunB doublet observed in untreated cells shifts to a single band of ~43 kDa in staurosporine-treated cells, with appearance of additional ~28 kDa fragment. This proteolytic processing can be blocked by pan-caspase inhibitors such as Z-VAD-FMK .

What is the significance of phosphorylation at Ser-259 of JunB, and how can it be studied?

Phosphorylation of JunB at serine 259 is a critical post-translational modification that modulates its transcriptional activity. To study this specific modification:

• Use phospho-specific antibodies: While JUNB (Ab-259) Antibody detects total JunB, phospho-specific antibodies targeting Ser-259 are available for detecting only the phosphorylated form .

• Dephosphorylation assays: Treat immunoprecipitated JunB with phosphatases (e.g., alkaline phosphatase) to confirm the identity of phosphorylated bands.

• EMSAs (Electrophoretic Mobility Shift Assays): These can assess how phosphorylation affects DNA binding activity to AP-1 sites.

Researchers should note that phosphorylation at Ser-259 affects JunB's electrophoretic mobility, contributing to the characteristic doublet pattern (~43-45 kDa) often observed in western blots. The upper band typically represents the phosphorylated form .

How does JUNB (Ab-259) Antibody compare with other antibodies targeting different JunB epitopes?

JUNB (Ab-259) Antibody targets a specific region around amino acids 257-261, which offers certain advantages and limitations compared to antibodies targeting other regions:

When designing experiments, consider using multiple antibodies targeting different epitopes to gain comprehensive insights into JunB processing and interactions .

What are the optimal conditions for Western blotting with JUNB (Ab-259) Antibody?

For optimal Western blotting results with JUNB (Ab-259) Antibody:

• Sample preparation:

  • Use fresh cell lysates when possible

  • Include phosphatase inhibitors to preserve phosphorylation status

  • Load 20-30 μg of total protein per lane

• Electrophoresis and transfer:

  • Use 10-12% SDS-PAGE gels for optimal resolution

  • Transfer to nitrocellulose membranes at 100V for 1 hour or 30V overnight

• Antibody incubation:

  • Block in 5% nonfat milk powder in TBS

  • Dilute primary antibody 1:500-1:1000 in blocking buffer

  • Incubate overnight at 4°C with gentle agitation

  • Wash thoroughly in 0.1% TBST (3-5 times, 5 minutes each)

  • Incubate with HRP-conjugated secondary antibody (1:5000-1:10000) for 1 hour at room temperature

• Detection:

  • Use enhanced chemiluminescence (ECL) substrate

  • Expected band size: ~43 kDa (may appear as a doublet ~43-45 kDa due to phosphorylation)

How should JUNB (Ab-259) Antibody be stored to maintain optimal activity?

Proper storage of JUNB (Ab-259) Antibody is crucial for maintaining its activity:

• Long-term storage: Store at -20°C in the provided buffer containing 50% glycerol.

• Working aliquots: To avoid repeated freeze-thaw cycles, prepare small working aliquots before freezing.

• Short-term storage: For antibody in use, store at 4°C for up to 6 months.

• Avoid:

  • Repeated freeze-thaw cycles

  • Storage in frost-free freezers with automatic defrost cycles

  • Prolonged exposure to room temperature

The antibody is typically supplied at 1.0 mg/mL in phosphate buffered saline (without Mg²⁺ and Ca²⁺), pH 7.4, 150mM NaCl, 0.02% sodium azide, and 50% glycerol, which helps maintain stability during storage .

What controls should be included when using JUNB (Ab-259) Antibody in experiments?

To ensure reliable and interpretable results with JUNB (Ab-259) Antibody, include the following controls:

• Positive controls:

  • HeLa cell lysates (known to express JunB)

  • Breast carcinoma tissue (for IHC applications)

• Negative controls:

  • Antibody preincubated with blocking peptide (specific competitive inhibition)

  • Secondary antibody only (to detect non-specific binding)

  • JunB-knockout or -knockdown samples (if available)

• Loading controls (for Western blotting):

  • β-actin, tubulin, or GAPDH antibodies to normalize protein loading

• Phosphorylation controls (if studying phosphorylation status):

  • Samples treated with phosphatase

  • Samples from cells treated with kinase activators/inhibitors

Including appropriate controls allows proper interpretation of results and troubleshooting of unexpected findings .

How can JUNB (Ab-259) Antibody be used in combination with other techniques to study AP-1 transcription complex formation?

JUNB (Ab-259) Antibody can be integrated with multiple techniques to investigate AP-1 complex formation:

• Co-immunoprecipitation (Co-IP):

  • Use JUNB (Ab-259) Antibody to immunoprecipitate JunB

  • Probe for interaction partners (e.g., c-Fos, Fra2) by Western blotting

  • Recommended protocol: Incubate 1-5 μg antibody with 500-1000 μg protein lysate overnight at 4°C

• Chromatin Immunoprecipitation (ChIP):

  • Use JUNB (Ab-259) Antibody to identify JunB-bound genomic regions

  • Follow with qPCR or sequencing to identify binding sites

• Electrophoretic Mobility Shift Assay (EMSA):

  • Use JUNB (Ab-259) Antibody for supershift assays to confirm JunB in DNA-protein complexes

  • Protocol: Preincubate nuclear extracts with antibody on ice for 15 minutes before adding biotinylated probe containing AP-1 binding sites (5'-TGA[CG]TCA-3')

• Proximity Ligation Assay (PLA):

  • Combine JUNB (Ab-259) Antibody with antibodies against other AP-1 components

  • Visualize protein-protein interactions in situ

These combined approaches can reveal the composition and dynamics of AP-1 complexes under different cellular conditions .

What methodological considerations are important when interpreting JunB phosphorylation at Ser-259?

When investigating JunB phosphorylation at Ser-259, consider these methodological aspects:

• Band pattern interpretation:

  • In Western blots, phosphorylated JunB typically appears as the upper band (~45 kDa) of a characteristic doublet

  • Treatment with phosphatase should collapse the doublet to a single lower band (~43 kDa)

• Phosphorylation-specific detection:

  • Use phospho-specific JunB (Phospho-Ser259) antibodies for direct detection

  • Compare results with total JunB detection using JUNB (Ab-259) Antibody

• Functional assays:

  • Correlate phosphorylation status with DNA binding activity using EMSA

  • Compare transcriptional activity of phosphorylated vs. non-phosphorylated JunB

• Signaling pathway analysis:

  • Consider the kinases that phosphorylate Ser-259 (potential candidates include JNK and ERK)

  • Use specific kinase inhibitors to modulate phosphorylation status

Understanding the phosphorylation state is critical as it affects JunB's protein-protein interactions, DNA binding affinity, and transcriptional activity .

How can JUNB (Ab-259) Antibody be used to investigate JunB degradation during cellular stress?

To study JunB degradation during cellular stress using JUNB (Ab-259) Antibody:

• Time-course experiments:

  • Treat cells with stress inducers (UV, oxidative stress, heat shock)

  • Collect samples at multiple time points (0, 15, 30, 60, 120 minutes)

  • Perform Western blotting with JUNB (Ab-259) Antibody to track protein levels

  • Quantify band intensity relative to loading controls

• Proteasome inhibition:

  • Pre-treat cells with proteasome inhibitors (MG132, bortezomib)

  • Compare JunB levels in stressed cells with and without inhibitors

  • This helps distinguish between proteasomal degradation and other mechanisms

• Caspase involvement:

  • Use caspase inhibitors (Z-VAD-FMK) to determine if JunB processing is caspase-dependent

  • Look for characteristic cleavage fragments (~28 kDa) using Western blotting

• Ubiquitination assays:

  • Immunoprecipitate JunB using JUNB (Ab-259) Antibody

  • Probe for ubiquitin by Western blotting to assess ubiquitination status

These approaches can reveal the mechanisms regulating JunB stability during different stress conditions and their potential impact on AP-1-dependent transcriptional programs .

What evidence confirms the specificity of JUNB (Ab-259) Antibody in experimental applications?

The specificity of JUNB (Ab-259) Antibody has been validated through multiple approaches:

• Peptide competition assays:

  • Western blot analysis of HeLa cell extracts shows specific detection of JunB that is abolished when the antibody is preincubated with its specific blocking peptide

  • Immunohistochemical staining of human breast carcinoma tissue is similarly blocked by peptide competition

• Molecular weight confirmation:

  • The antibody consistently detects a protein of the expected molecular weight (~43 kDa, sometimes appearing as a doublet ~43-45 kDa due to phosphorylation)

• Reactivity profile:

  • The antibody shows the expected reactivity pattern across human, mouse, and rat samples, consistent with the conserved nature of the epitope

• Detection of known modifications:

  • The antibody successfully detects changes in JunB during apoptosis, including the appearance of characteristic cleavage fragments

These validation studies provide strong evidence for the specificity of JUNB (Ab-259) Antibody in detecting its target protein.

What are the limitations of using JUNB (Ab-259) Antibody in research applications?

Researchers should be aware of several limitations when using JUNB (Ab-259) Antibody:

• Cross-reactivity considerations:

  • While designed to detect JunB, potential cross-reactivity with closely related AP-1 family members (particularly c-Jun) should be considered in experimental design

  • Validation in JunB-knockout systems is recommended for critical applications

• Detection of modified forms:

  • The antibody detects total JunB regardless of most post-translational modifications

  • May not distinguish between phosphorylated and non-phosphorylated forms at Ser-259

  • For specific detection of phosphorylated JunB, phospho-specific antibodies should be used

• Application constraints:

  • May not be optimal for all applications; specifically validated for WB and IHC

  • Performance in other applications like flow cytometry or immunoprecipitation may require additional optimization

• Technical variables:

  • Batch-to-batch variability may exist; validation with new lots is recommended

  • Performance can be affected by sample preparation methods and buffer conditions

Understanding these limitations allows researchers to design appropriate controls and interpret results accurately.

How does JunB phosphorylation at Ser-259 influence its function in the AP-1 transcription complex?

JunB phosphorylation at Ser-259 has significant functional implications:

• Transcriptional activity:

  • Phosphorylation at Ser-259 modulates JunB's transcriptional activity, affecting its ability to regulate target gene expression

  • The phosphorylated form shows altered DNA binding characteristics to AP-1 sites

• Protein-protein interactions:

  • Phosphorylation influences JunB's ability to heterodimerize with Fos family proteins

  • This affects the composition and activity of the AP-1 transcription complex

• Structural evidence:

  • Electrophoretic mobility shift assays (EMSAs) demonstrate that phosphorylation status affects DNA binding activity

  • Phosphorylated JunB shows different mobility patterns in gel electrophoresis, typically appearing as the upper band of a characteristic doublet

• Biological significance:

  • Phosphorylation serves as a regulatory mechanism to fine-tune JunB's activity in response to various cellular signals

  • This post-translational modification is particularly important in contexts such as growth factor response and cellular stress

Understanding the functional implications of Ser-259 phosphorylation provides insights into the regulatory mechanisms controlling AP-1-dependent transcriptional programs .

How can JUNB (Ab-259) Antibody be used in studying cancer signaling pathways?

JUNB (Ab-259) Antibody offers several methodological approaches for investigating cancer signaling:

• Expression profiling across cancer types:

  • Use IHC with JUNB (Ab-259) Antibody on tissue microarrays to compare JunB expression across tumor types and correlate with clinical parameters

  • Western blot analysis of cancer cell lines to establish baseline expression patterns

• Response to targeted therapies:

  • Monitor JunB levels and phosphorylation status after treatment with kinase inhibitors or other targeted agents

  • Correlate changes in JunB with treatment response or resistance mechanisms

• Integration with oncogenic pathways:

  • Combined analysis with markers of other signaling pathways (MAPK, JAK/STAT, PI3K/AKT)

  • Co-staining approaches in IHC or multiplexed protein analysis

• Chromatin immunoprecipitation sequencing (ChIP-seq):

  • Use JUNB (Ab-259) Antibody to identify genome-wide binding sites in cancer cells

  • Compare binding profiles between normal and malignant cells

JunB has been implicated in various cancer types, including breast carcinoma, where JUNB (Ab-259) Antibody has been validated for IHC applications .

What approaches can be used to quantify JunB levels in complex biological samples?

For accurate quantification of JunB in complex samples:

• Quantitative Western blotting:

  • Use recombinant JunB protein to create a standard curve

  • Include multiple loading amounts of standard alongside samples

  • Apply JUNB (Ab-259) Antibody at optimized dilution (1:500-1:1000)

  • Use digital image analysis software for densitometry

  • Normalize to loading controls (β-actin, GAPDH)

• ELISA-based quantification:

  • Sandwich ELISA with capture antibody and JUNB (Ab-259) Antibody as detection antibody

  • Standard curves with recombinant JunB protein

  • Dilution series of samples to ensure measurements within linear range

• Mass spectrometry approaches:

  • Immunoprecipitation with JUNB (Ab-259) Antibody followed by MS analysis

  • Selected reaction monitoring (SRM) or parallel reaction monitoring (PRM) for targeted quantification

  • Use stable isotope-labeled peptide standards for absolute quantification

• Digital pathology for IHC:

  • Stain tissue sections with JUNB (Ab-259) Antibody (1:50-1:100 dilution)

  • Use digital image analysis algorithms to quantify nuclear staining intensity

  • Compare against appropriate controls for relative quantification

These methods provide complementary approaches for JunB quantification in different experimental contexts .