Phospho-CEBPA (Ser21) Antibody

What is Phospho-CEBPA (Ser21) Antibody and what cellular processes does it help investigate?

Phospho-CEBPA (Ser21) Antibody is a specialized immunological reagent designed to detect CCAAT/enhancer-binding protein alpha (C/EBPα) specifically when phosphorylated at serine 21. C/EBPα functions as a critical transcription factor involved in regulating gene expression and cellular differentiation . This antibody enables researchers to investigate phosphorylation-dependent activity of C/EBPα, which plays significant roles in various biological processes including:

• Cell cycle regulation

• Body weight homeostasis

• Cellular differentiation pathways

• Metabolic processes

The phosphorylation status at Ser21 specifically modulates C/EBPα activity, making it a valuable target for research in cancer biology, inflammation studies, and metabolic research . This antibody provides a powerful tool for studying how phosphorylation events affect transcriptional regulation in different physiological and pathological conditions.

What are the validated applications for Phospho-CEBPA (Ser21) Antibody?

The Phospho-CEBPA (Ser21) Antibody has been validated for multiple research applications, each requiring specific optimization parameters:

For Western Blotting applications, the antibody reliably detects a band at approximately 42-45 kDa, representing the phosphorylated form of C/EBPα . When utilizing this antibody across different applications, researchers should perform preliminary titration experiments to determine optimal antibody concentration for their specific experimental system and biological samples.

What species reactivity has been confirmed for Phospho-CEBPA (Ser21) Antibody?

The Phospho-CEBPA (Ser21) Antibody demonstrates confirmed reactivity across several mammalian species:

• Human

• Mouse

• Rat

This cross-species reactivity is supported by the high conservation of the epitope region (amino acids 6-55) surrounding the Ser21 phosphorylation site . The antibody was generated using a synthetic peptide derived from human C/EBP-alpha around the phosphorylation site of Ser21, but homology analysis confirms its utility in detecting the phosphorylated protein in rodent models as well . This multi-species reactivity makes the antibody particularly valuable for comparative studies and for validating findings across different experimental models.

What are the recommended storage and handling conditions for Phospho-CEBPA (Ser21) Antibody?

To maintain antibody integrity and performance, follow these storage and handling recommendations:

• Store at -20°C for up to one year from the date of receipt

• Avoid repeated freeze-thaw cycles to prevent denaturation

• The antibody is typically supplied in PBS containing 50% glycerol, 0.5% BSA, and 0.02% sodium azide

• Upon receipt, consider preparing small working aliquots to minimize freeze-thaw cycles

• Prior to use, thaw aliquots at room temperature and mix gently to ensure homogeneity

Proper storage and handling are critical for maintaining antibody specificity and sensitivity. Inappropriate storage conditions can lead to reduced binding efficiency and increased background, compromising experimental results and reproducibility.

How can researchers validate the specificity of Phospho-CEBPA (Ser21) Antibody in their experimental systems?

Validating antibody specificity is essential for generating reliable research data. For Phospho-CEBPA (Ser21) Antibody, employ these comprehensive validation strategies:

• Phosphatase Treatment Control: Treat one sample with lambda phosphatase before immunoblotting to demonstrate phospho-specificity. The signal should disappear in treated samples.

• Peptide Competition Assay: Pre-incubate the antibody with excess phospho-peptide immunogen (derived from amino acids 6-55 around Ser21) before application to samples. Signal reduction confirms specificity.

• Phosphorylation-Inducing Treatments: Employ treatments known to increase Ser21 phosphorylation (e.g., certain kinase activators) and compare with baseline or inhibitor-treated samples.

• Genetic Knockdown/Knockout Controls: Utilize CEBPA-knockdown or knockout models as negative controls. The antibody should show significantly reduced or absent signal in these samples.

• Ser21 Mutant Expression: Express S21A (non-phosphorylatable) mutant in cells and compare with wild-type CEBPA. The antibody should not detect the S21A mutant.

The manufacturer confirms that this antibody detects endogenous levels of C/EBP-alpha protein only when phosphorylated at Ser21 , but independent validation in your specific experimental system is always recommended for rigorous research applications.

What are the optimal protocols for using Phospho-CEBPA (Ser21) Antibody in Western blotting applications?

For optimal Western blotting results with Phospho-CEBPA (Ser21) Antibody, follow this detailed protocol:

• Sample Preparation:

  • Extract proteins using buffer containing phosphatase inhibitors (e.g., sodium fluoride, sodium orthovanadate)

  • Maintain samples on ice and process rapidly to prevent dephosphorylation

  • Quantify protein concentration (Bradford or BCA assay) and normalize loading

• Gel Electrophoresis:

  • Load 20-50 μg of total protein per lane

  • Use 10-12% SDS-PAGE gels for optimal resolution around 42-45 kDa

• Transfer:

  • Perform wet transfer to PVDF or nitrocellulose membrane

  • Transfer at 100V for 60-90 minutes or 30V overnight at 4°C

• Blocking:

  • Block with 5% BSA (preferred over milk for phospho-antibodies) in TBST for 1 hour at room temperature

• Primary Antibody Incubation:

  • Dilute antibody 1:1000 in 5% BSA/TBST

  • Incubate overnight at 4°C with gentle agitation

• Washing:

  • Wash membrane 3-5 times with TBST, 5 minutes each

• Secondary Antibody:

  • Incubate with HRP-conjugated anti-rabbit secondary antibody (1:5000-1:10000)

  • Dilute in 5% BSA/TBST

  • Incubate for 1 hour at room temperature

• Detection:

  • Wash 3-5 times with TBST

  • Develop using enhanced chemiluminescence substrate

  • Expected band size: 42-45 kDa

For challenging applications, consider using signal enhancers or more sensitive detection systems to visualize low abundance phosphorylated proteins.

What factors influence CEBPA Ser21 phosphorylation, and how can researchers modulate this modification experimentally?

CEBPA Ser21 phosphorylation is regulated by multiple signaling pathways and can be experimentally modulated:

• Known Regulatory Kinases:

  • PKA (Protein Kinase A) has been implicated in phosphorylating Ser21

  • p38 MAPK pathway may indirectly influence Ser21 phosphorylation

  • GSK3β has been reported to phosphorylate Ser21 under certain conditions

• Experimental Induction Strategies:

  • Treatment with phorbol esters (e.g., PMA) can activate PKC pathways affecting CEBPA phosphorylation

  • Growth factor stimulation (insulin, EGF) can modulate Ser21 phosphorylation through downstream signaling cascades

  • Glucose concentration changes in media can alter metabolic signaling affecting CEBPA phosphorylation

• Inhibition Approaches:

  • Small molecule kinase inhibitors targeting upstream regulators

  • ATP-competitive inhibitors for relevant kinases

  • Expression of dominant-negative kinase mutants

• Physiological Conditions:

  • Differentiation states (particularly adipocyte and myeloid differentiation) influence phosphorylation patterns

  • Cell cycle position affects CEBPA phosphorylation status

  • Metabolic stress conditions alter phosphorylation profiles

Understanding these regulatory mechanisms is essential when designing experiments to study the functional consequences of Ser21 phosphorylation on CEBPA's transcriptional activity and its role in cellular processes like differentiation and metabolism.

How can Phospho-CEBPA (Ser21) Antibody be effectively used in immunohistochemistry for tissue samples?

For successful immunohistochemistry (IHC) with Phospho-CEBPA (Ser21) Antibody, follow this optimized protocol:

• Tissue Preparation:

  • Fix tissues in 10% neutral buffered formalin for 24-48 hours

  • Process and embed in paraffin

  • Cut sections at 4-6 μm thickness

  • Mount on positively charged slides

• Antigen Retrieval (critical for phospho-epitopes):

  • Heat-induced epitope retrieval using citrate buffer (pH 6.0) or EDTA buffer (pH 9.0)

  • Pressure cooker method: 125°C for 3 minutes or 95-100°C for 20 minutes

• Endogenous Peroxidase Blocking:

  • Treat with 3% hydrogen peroxide for 10 minutes

  • Wash thoroughly with PBS

• Background Blocking:

  • Block with 2-5% normal goat serum in PBS for 30-60 minutes

• Primary Antibody Incubation:

  • Dilute antibody 1:100-1:300 in blocking buffer

  • Incubate in humidified chamber at 4°C overnight

• Detection System:

  • Use polymer-based detection system for enhanced sensitivity

  • Apply as per manufacturer's instructions

  • Develop with DAB substrate until optimal signal (typically 2-5 minutes)

• Counterstaining:

  • Counterstain with hematoxylin for 1-2 minutes

  • Blue with lithium carbonate or tap water

• Controls:

  • Include phosphatase-treated sections as negative controls

  • Use tissues known to express phosphorylated CEBPA as positive controls

In validated samples, phosphorylated CEBPA (Ser21) demonstrates predominantly nuclear localization, consistent with its role as a transcription factor . Optimization of antigen retrieval conditions is particularly important for phospho-epitopes, which can be sensitive to fixation variables.

What are the critical considerations when troubleshooting inconsistent results with Phospho-CEBPA (Ser21) Antibody?

When encountering inconsistent results with Phospho-CEBPA (Ser21) Antibody, systematically address these critical factors:

• Phosphorylation Status Preservation:

  • Ensure rapid sample processing with immediate addition of phosphatase inhibitors

  • Verify phosphatase inhibitor cocktail includes both serine/threonine and tyrosine phosphatase inhibitors

  • Consider flash-freezing samples in liquid nitrogen before processing

• Antibody-Specific Variables:

  • Verify antibody storage conditions and expiration date

  • Test multiple antibody dilutions (perform titration experiments)

  • Consider lot-to-lot variations and request technical information on specific lot performance

• Technical Optimization:

  • For Western blotting: Adjust protein loading (20-50 μg), transfer conditions, and blocking agents

  • For IHC/IF: Optimize antigen retrieval methods, incubation times, and detection systems

  • For all applications: Test alternative buffer compositions and pH conditions

• Biological Sample Considerations:

  • Cell culture: Confluence level, passage number, and serum starvation status affect phosphorylation

  • Tissues: Ischemia time, fixation duration, and processing methods impact phospho-epitope preservation

  • Verify expression levels of total CEBPA in your biological system

• Positive Controls:

  • Include samples with known high levels of Ser21 phosphorylation

  • Consider using cell lines treated with phosphatase inhibitors as positive controls

  • For advanced applications, use cells transfected with phospho-mimetic CEBPA mutants

• Cross-Reactivity Assessment:

  • Test for potential cross-reactivity with other phosphorylated C/EBP family members

  • Perform additional validation in systems with genetic manipulation of CEBPA

By systematically addressing these variables, researchers can improve reproducibility and reliability of results when working with Phospho-CEBPA (Ser21) Antibody across different experimental platforms.