CBP2 Antibody

What is CBP2 and what molecular functions does it perform?

CBP2 (CREB-binding protein 2) belongs to a family of histone acetyltransferases that play critical roles in transcriptional regulation and chromatin remodeling. Different organisms have evolved distinct CBP family members with specialized functions. In planarians, for instance, CBP2 is essential for stem cell maintenance, with knockdown causing rapid and dramatic loss of stem cells . This differs from its paralog CBP3, which more narrowly affects stem cells with a preference for neural progenitors . The CBP family's functions generally involve acetylation of histones and other proteins, facilitating gene expression through chromatin structure modification.

It's important to note that "CBP2" can refer to different proteins depending on context:

• In planarians: A CBP/p300 ortholog involved in stem cell maintenance

• In mammals: Sometimes refers to CtBP2 (C-terminal binding protein 2), a transcriptional corepressor

• In other contexts: May refer to Carboxypeptidase B2 (thrombin-activatable fibrinolysis inhibitor)

When planning experiments, it's crucial to clearly identify which specific protein is being targeted.

How should I select the appropriate CBP2 antibody for my specific research applications?

Selecting the right CBP2 antibody requires careful consideration of several factors:

• Target species specificity: Ensure the antibody recognizes your species of interest. For example, the CtBP2 antibody (#13256) from Cell Signaling Technology shows reactivity with human, mouse, rat, and monkey proteins . Similarly, the Human Carboxypeptidase B2/CPB2 antibody (MAB6036) is specific for human samples with approximately 20% cross-reactivity to recombinant human proteins .

• Application compatibility: Verify the antibody has been validated for your intended application. For instance, the CtBP2 antibody (#13256) has been validated for Western blotting (1:1000 dilution) and immunoprecipitation (1:50 dilution) .

• Epitope location: Consider whether the epitope is accessible in your experimental conditions, especially if the protein undergoes post-translational modifications or interactions that might mask binding sites.

• Validation data: Review the manufacturer's validation data, including Western blot images showing expected molecular weight bands. The Human Carboxypeptidase B2/CPB2 antibody detects specific bands at approximately 45 and 50 kDa under non-reducing conditions .

• Monoclonal vs. polyclonal: Monoclonal antibodies like the Human Carboxypeptidase B2/CPB2 antibody (Clone # 650801) offer high specificity, while polyclonal antibodies may provide better sensitivity but potential cross-reactivity .

What are the recommended protocols for CBP2 antibody-based western blotting?

For optimal western blotting results with CBP2 antibodies, follow these methodological guidelines:

• Sample preparation:

  • For cell lysates: Use buffer containing appropriate protease inhibitors to prevent degradation

  • For tissue samples: Homogenize thoroughly in lysis buffer (e.g., 20 mM Tris-HCl, pH 7.5, 100 mM NaCl, 1 mM EDTA, and 0.5% NP-40)

• Protein loading and separation:

  • Load 20-50 μg total protein per lane

  • Use appropriate percentage gels based on target protein size (8-10% for CBP family proteins)

  • Include molecular weight markers spanning the expected protein size

• Transfer conditions:

  • For CBP family proteins (large size), use wet transfer at lower voltage for longer duration

  • PVDF membrane is recommended for CBP2 detection as used for Human Carboxypeptidase B2/CPB2

• Blocking and antibody incubation:

  • Block with 5% non-fat dry milk or BSA in TBST

  • For primary antibody incubation:

    • CtBP2 antibody: 1:1000 dilution

    • Human Carboxypeptidase B2/CPB2 antibody: 2 μg/mL

  • Incubate overnight at 4°C for optimal results

  • For secondary antibody: Use HRP-conjugated anti-species IgG (typically 1:5000-1:10000)

• Detection and analysis:

  • Use enhanced chemiluminescence (ECL) for visualization

  • Expected molecular weights:

    • Human Carboxypeptidase B2/CPB2: ~45-50 kDa

    • CtBP2: ~47 kDa

• Controls:

  • Include positive control tissue/cell lysates known to express the target

  • Consider using knockout/knockdown samples as negative controls

How can I optimize CBP2 antibody-based immunoprecipitation protocols?

Successful immunoprecipitation with CBP2 antibodies requires careful optimization:

• Cell lysis optimization:

  • Use gentle lysis conditions to preserve protein-protein interactions

  • A recommended lysis buffer contains: 20 mM Tris-HCl, pH 7.5, 100 mM NaCl, 1 mM EDTA, and 0.5% NP-40

  • Include protease and phosphatase inhibitors to preserve post-translational modifications

• Antibody selection and quantity:

  • For CBP immunoprecipitation, 2 μg of antibody per sample has been demonstrated to be effective

  • For CtBP2 antibody (#13256), a 1:50 dilution is recommended for immunoprecipitation

• Immunoprecipitation procedure:

  • Incubate lysate with antibody for 3 hours at 4°C with rotation

  • Add 15 μl of protein A/protein G-Sepharose beads (50:50 mix)

  • Continue incubation overnight at 4°C under rotation

  • Perform gentle centrifugation to pellet immune complexes

  • Wash three times with lysis buffer

• Elution and analysis:

  • Elute proteins by boiling in SDS-PAGE loading buffer

  • Analyze by western blotting using appropriate antibodies

• Common pitfalls to avoid:

  • Insufficient antibody amount leading to poor pull-down efficiency

  • Excessive washing causing loss of specific interactions

  • Inadequate blocking of beads resulting in high background

What are the experimental considerations when studying CBP2's role in stem cell biology?

Based on research with planarian CBP2, several key considerations emerge when investigating its role in stem cell biology:

• RNAi knockdown design:

  • In planarian studies, consistent RNAi feeding protocols (days 0, 6, and 10) effectively reduced CBP2 expression

  • Observe for phenotypes 2-3 days after final RNAi treatment

• Stem cell markers assessment:

  • Monitor established stem cell markers (e.g., smedwi-1 in planarians) to assess stem cell maintenance

  • Use RT-qPCR to quantify changes in stem cell-enriched transcripts following CBP2 manipulation

• Differential analysis of stem cell populations:

  • Compare effects on broadly expressed stem cell markers versus lineage-specific markers

  • In planarians, CBP2 knockdown affected broad stem cell populations, contrasting with CBP3's more restricted effects on neural progenitors

• Regeneration assays:

  • When applicable, assess regenerative capacity following CBP2 manipulation

  • In planarian models, animals can be amputated pre-pharyngeally and trunk pieces observed during regeneration

• Temporal considerations:

  • Monitor phenotypes over time, as CBP2 knockdown can cause rapid stem cell loss

  • Document the timeline of stem cell marker reduction versus onset of morphological defects

• Controls:

  • Include paralog knockdowns (e.g., CBP3) to distinguish specific roles

  • Consider irradiation experiments to compare with CBP2 knockdown effects on stem cell populations

How do I interpret unexpected banding patterns in CBP2 western blots?

When encountering unexpected bands in CBP2 western blots, consider these analytical approaches:

• Multiple specific bands:

  • Human Carboxypeptidase B2/CPB2 antibody detects specific bands at approximately 45 and 50 kDa under non-reducing conditions

  • These may represent:

    • Different isoforms due to alternative splicing

    • Post-translational modifications

    • Proteolytic processing products

• Higher molecular weight bands:

  • May indicate:

    • Protein dimers/multimers if sample preparation was insufficient

    • Post-translational modifications (e.g., ubiquitination, SUMOylation)

    • Protein complexes resistant to denaturation

• Lower molecular weight bands:

  • Could represent:

    • Degradation products (evaluate protease inhibitor effectiveness)

    • Alternative translation start sites

    • Proteolytic fragments with biological significance

• Validation approaches:

  • Compare reducing vs. non-reducing conditions

  • Perform peptide competition assays

  • Compare results with different antibodies targeting distinct epitopes

  • Analyze samples from knockout/knockdown models

• Technical troubleshooting:

  • For non-specific bands, optimize:

    • Blocking conditions (try different blocking agents)

    • Antibody dilutions

    • Washing stringency

    • Consider using gradient gels for better resolution

What are the critical controls for CBP2 antibody validation?

Comprehensive validation of CBP2 antibodies should include these essential controls:

• Positive and negative tissue/cell controls:

  • Positive: Tissues known to express the target (e.g., liver for human CPB2)

  • Negative: Tissues with minimal expression or knockout/knockdown samples

• Peptide competition assay:

  • Pre-incubate antibody with immunizing peptide

  • Signal should be significantly reduced or eliminated

• Multiple detection methods:

  • Compare results across applications (Western blot, immunoprecipitation, immunohistochemistry)

  • For example, the CtBP2 antibody (#13256) has been validated for both Western blotting and immunoprecipitation

• Antibody specificity controls:

  • Test cross-reactivity with related family members

  • For instance, assess whether CBP2 antibodies cross-react with other CBP family proteins (CBP1, CBP3, etc.)

• Molecular weight verification:

  • Confirm that detected bands match predicted molecular weights

  • Human Carboxypeptidase B2/CPB2: ~45-50 kDa

  • CtBP2: ~47 kDa

• Expression manipulation:

  • Overexpression: Should increase signal intensity

  • knockdown/knockout: Should decrease or eliminate signal

• Cross-species validation:

  • When applicable, test antibody reactivity across species of interest

  • CtBP2 antibody (#13256) shows reactivity with human, mouse, rat, and monkey proteins

How can I determine the optimal CBP2 antibody concentration for different applications?

Determining optimal antibody concentration requires systematic titration across applications:

Western Blotting Optimization:

Recommended dilutions based on literature:

• CtBP2 antibody (#13256): 1:1000

• Human Carboxypeptidase B2/CPB2 antibody: 2 μg/mL

Immunoprecipitation Optimization:

• Start with manufacturer's recommended dilution (e.g., 1:50 for CtBP2 antibody)

• Adjust antibody amount based on target abundance:

  • For abundant proteins: 1-2 μg antibody

  • For low-abundance proteins: 2-5 μg antibody

• For CBP immunoprecipitation, 2 μg has been successfully used in published protocols

ELISA Optimization:

• Perform checkerboard titration:

  • Test antibody at dilutions from 1:100 to 1:10,000

  • Evaluate against varying antigen concentrations

• Select dilution that provides good dynamic range and low background

• Human Carboxypeptidase B2/CPB2 antibody has been validated for direct ELISA applications

What technical considerations are important when analyzing CBP2 histone acetyltransferase activity?

When analyzing CBP2 histone acetyltransferase (HAT) activity, consider these methodological details:

• Sample preparation:

  • Immunoprecipitate CBP using established protocols (e.g., incubate lysate with 2 μg CBP antibody for 3 hours at 4°C)

  • After washing immune complexes, they can be directly used in HAT assays

• HAT activity assay options:

  • In vitro biochemical assays:

    • Use purified histones or histone peptides as substrates

    • Include 14C or 3H-labeled acetyl-CoA as acetyl donor

    • Measure incorporation by filter binding or liquid scintillation counting

  • Cell-based assays:

    • Analyze histone acetylation levels using anti-acetyl-lysine antibodies (e.g., antibody 193 from abcam at 1:100 dilution)

    • Target specific lysine residues with modification-specific antibodies

• Controls and normalization:

  • Include known HAT inhibitors as negative controls

  • Normalize activity to CBP protein levels determined by western blot

  • Include wild-type and catalytically inactive CBP mutants as controls

• Factors that modulate CBP HAT activity:

  • Protein-protein interactions can significantly impact activity

  • For example, SV40 T antigen has been shown to modulate CBP HAT activity

  • Consider the influence of experimental conditions on these regulatory interactions

• Substrate specificity considerations:

  • CBP can acetylate multiple histone residues (primarily H3 and H4)

  • Non-histone proteins can also serve as substrates

  • When assessing specific substrates, include appropriate controls

How does CBP2 function compare across different model organisms?

CBP2 functions show important evolutionary differences across model organisms:

• Planarians (Schmidtea mediterranea):

  • CBP family is expanded with five paralogs (CBP1-5)

  • CBP2 is critical for stem cell maintenance, with knockdown causing rapid stem cell loss

  • CBP3 has a more restricted role primarily affecting neural progenitors

  • Both CBP2 and CBP3 are essential for planarian survival

• Mammals:

  • Mammals typically have fewer CBP family members compared to planarians

  • CBP and p300 are the primary family members with HAT activity

  • CtBP2 (sometimes abbreviated as CBP2) functions as a transcriptional corepressor rather than a HAT

• Expression patterns:

  • In planarians, CBP2 shows broad expression patterns suggesting functions in multiple cell types

  • Unlike CBP5 (which is enriched in stem cells), CBP2 expression remains relatively constant after irradiation-induced stem cell ablation

• Functional specialization:

  • The "division of labor" among CBP family members in planarians presents an opportunity to dissect specific functions in stem cell biology

  • This evolutionary divergence contrasts with the more pleiotropic roles of mammalian CBP/p300

What is the relationship between CBP2 and stem cell regulation pathways?

Research on planarian CBP2 has revealed important connections to stem cell regulation:

• Direct effects on stem cell maintenance:

  • CBP2 knockdown causes a dramatic, rapid loss of stem cells in planarians

  • This effect is evidenced by decreased expression of the stem cell marker smedwi-1

  • RT-qPCR analysis confirms reduction of various stem cell-enriched transcripts following CBP2 depletion

• Comparison with other regulators:

  • Studies have identified roles for diverse genes including bruli and piwi homologs in stem cell proliferation and self-renewal

  • CBP2's role appears to be distinct, with more severe and rapid effects on stem cell survival

• Potential mechanisms:

  • As a histone acetyltransferase, CBP2 likely regulates chromatin structure

  • This may facilitate access of transcription factors to genes essential for stem cell identity

  • The dramatic phenotype suggests CBP2 may regulate a broad program of stem cell-specific genes

• Paralog-specific functions:

  • Unlike CBP2, CBP3 knockdown more narrowly affects stem cells with preference for neural progenitors

  • This suggests evolutionary specialization of paralogous CBP proteins for distinct aspects of stem cell regulation

• Relevance to regeneration:

  • Planarian regenerative capacity depends on stem cell function

  • CBP2's essential role in stem cell maintenance directly impacts regenerative potential

What troubleshooting strategies should I employ when CBP2 antibodies show inconsistent results?

When facing inconsistent results with CBP2 antibodies, implement these systematic troubleshooting approaches:

• Antibody validation issues:

  • Confirm antibody lot consistency (request Certificate of Analysis)

  • Re-validate antibody using positive control samples

  • Consider testing alternative antibodies targeting different epitopes

• Sample preparation variables:

  • Standardize cell/tissue lysis protocols

  • Evaluate protein degradation using fresh protease inhibitors

  • For nuclear proteins like CBP family members, ensure efficient nuclear extraction

• Technical optimization for Western blots:

  • If bands are weak or absent:

    • Increase protein loading (up to 50 μg)

    • Reduce antibody dilution (e.g., from 1:1000 to 1:500)

    • Extend primary antibody incubation (overnight at 4°C)

    • Try alternative blockers (switch between milk and BSA)

  • If background is high:

    • Increase blocking time and concentration

    • Perform more stringent washes

    • Increase antibody dilution

• Application-specific troubleshooting:

  • For immunoprecipitation:

    • Increase lysate amount and antibody concentration

    • Optimize incubation times for antibody-antigen binding

    • Try different bead types (protein A vs. protein G vs. mixed)

    • Use the recommended 15 μl of protein A/protein G-Sepharose beads (50:50 mix)

• Sample-specific factors:

  • Consider cell type variation in target protein expression

  • Evaluate effects of cell treatments on protein expression or modifications

  • Assess influence of cell confluence and passage number

• Experimental design adjustments:

  • Include additional positive and negative controls

  • Perform parallel experiments with well-established targets

  • Document all experimental variables for systematic evaluation

How can CBP2 antibodies be utilized for chromatin immunoprecipitation sequencing (ChIP-seq)?

While specific ChIP-seq protocols using CBP2 antibodies aren't detailed in the provided search results, here's a methodological approach based on general principles and knowledge of CBP family proteins:

• Cross-linking optimization:

  • Standard formaldehyde cross-linking (1% for 10 minutes) is typically sufficient

  • For weaker or transient interactions, consider dual cross-linking with DSG followed by formaldehyde

• Chromatin preparation:

  • Sonicate to achieve fragments of 200-500 bp

  • Verify fragmentation efficiency by agarose gel electrophoresis

  • Remove insoluble material by centrifugation

• Immunoprecipitation conditions:

  • Pre-clear chromatin with protein A/G beads

  • Incubate with CBP2 antibody overnight at 4°C

  • Starting point: 2-5 μg antibody per ChIP reaction

  • Include appropriate controls (IgG, input samples)

• Washing and elution:

  • Perform stringent washes to reduce background

  • Elute DNA-protein complexes and reverse cross-links

  • Purify DNA using standard phenol-chloroform extraction or column-based methods

• Library preparation and sequencing:

  • Prepare libraries using standard ChIP-seq protocols

  • Target 20-50 million reads per sample for adequate coverage

• Data analysis considerations:

  • As a histone acetyltransferase, CBP2 binding may correlate with active regulatory regions

  • Consider parallel analysis of histone acetylation marks (H3K27ac)

  • Integrate with transcriptomic data to correlate binding with gene expression

What are the considerations for using CBP2 antibodies in multiplexed imaging studies?

For researchers planning multiplexed imaging with CBP2 antibodies, consider these methodological approaches:

• Antibody panel selection:

  • Ensure CBP2 antibody species compatibility with other antibodies in the panel

  • Validate that CBP2 antibody performs well under chosen fixation conditions

  • Test for potential cross-reactivity with other targets in the panel

• Multiplexing strategies:

  • Sequential staining with fluorophore stripping:

    • Perform initial staining with CBP2 antibody

    • Image and record positions

    • Strip antibodies using mild elution buffer

    • Repeat with next antibody set

  • Spectral unmixing:

    • Use spectrally distinct fluorophores for each target

    • Apply computational unmixing algorithms to separate overlapping signals

  • Mass cytometry/imaging mass cytometry:

    • Label CBP2 antibody with rare earth metals

    • Allows for simultaneous detection of 40+ markers without fluorescence overlap

• Antigen retrieval optimization:

  • As a nuclear protein, CBP2 may require optimized antigen retrieval

  • Test both heat-induced (citrate, EDTA) and enzymatic (proteinase K) methods

  • Determine compatibility of retrieval method with other targets

• Signal amplification considerations:

  • For low-abundance targets, consider tyramide signal amplification

  • Evaluate whether amplification causes increased background or affects other channels

• Controls for multiplexed experiments:

  • Single-stain controls for each antibody

  • Fluorescence minus one (FMO) controls

  • Processing controls to account for potential signal loss during cycles

How can I design experiments to study CBP2 interactions with regulatory proteins?

To investigate CBP2 interactions with regulatory proteins, consider these experimental approaches:

• Co-immunoprecipitation strategies:

  • Use established CBP immunoprecipitation protocols (2 μg antibody, 3-hour incubation, followed by protein A/G beads)

  • Analyze precipitates for interacting partners by western blot

  • For novel interactions, consider mass spectrometry analysis of precipitated complexes

• Proximity ligation assay (PLA):

  • Allows visualization of protein-protein interactions in situ

  • Requires antibodies raised in different species

  • Provides spatial information about interaction localization

• Bimolecular fluorescence complementation (BiFC):

  • Generate fusion constructs of CBP2 and potential interactors with split fluorescent protein fragments

  • Interaction brings fragments together, restoring fluorescence

  • Enables live-cell visualization of interactions

• Modulation experiments:

  • Study how interactions are affected by:

    • Cell treatments (differentiation signals, stress conditions)

    • Mutations in interaction domains

    • Post-translational modifications

  • For example, studies have shown that SV40 T antigen can modulate CBP HAT activity

• Domain mapping:

  • Use truncation or deletion constructs to identify specific interaction domains

  • For CBP family proteins, consider the HAT domain, bromodomain, and KIX domain as potential interaction surfaces

• Functional consequences assessment:

  • Determine how interactions affect:

    • CBP2 HAT activity

    • Target gene expression

    • Chromatin structure at regulated loci

  • Employ readouts such as histone acetylation levels using anti-acetyl-lysine antibodies

What emerging technologies are improving CBP2 antibody applications in research?

Recent technological advances are enhancing CBP2 antibody applications:

• Single-cell protein analysis:

  • Integration with single-cell transcriptomics for multi-modal analysis

  • Correlation of CBP2 protein levels with gene expression patterns at single-cell resolution

  • Application to heterogeneous stem cell populations to understand CBP2's role in cellular states

• High-throughput imaging:

  • Automated microscopy platforms for large-scale screening

  • Machine learning algorithms for image analysis and feature extraction

  • Quantitative assessment of CBP2 localization across experimental conditions

• Engineered antibody formats:

  • Single-domain antibodies with improved tissue penetration

  • Recombinant antibody fragments with defined specificity

  • Site-specific conjugation chemistries for precise labeling

• Live-cell applications:

  • Cell-permeable antibody fragments for intracellular protein tracking

  • Integration with genome editing to create endogenously tagged CBP2

  • Real-time monitoring of CBP2 dynamics during cellular processes

• Spatial proteomics:

  • Multiplexed antibody-based imaging at subcellular resolution

  • Digital spatial profiling for quantitative protein measurements in tissue context

  • Integration with spatial transcriptomics for multi-modal tissue analysis

These emerging technologies will enable more comprehensive understanding of CBP2 function in complex biological systems and disease states.

How can I best integrate CBP2 antibody data with other molecular datasets?

Effective integration of CBP2 antibody data with other molecular datasets requires thoughtful analytical approaches:

• Multi-omics integration strategies:

  • Correlate CBP2 ChIP-seq binding with histone modification patterns

  • Integrate with RNA-seq to connect binding with transcriptional outcomes

  • Combine with proteomics data to understand protein interaction networks

• Computational analysis approaches:

  • Apply network analysis algorithms to identify regulatory hubs

  • Use machine learning for pattern recognition across datasets

  • Employ dimensionality reduction techniques for visualizing complex relationships

• Temporal and spatial considerations:

  • Design experiments to capture dynamic changes in CBP2 activity

  • Consider tissue-specific or cell-type-specific analyses

  • Account for developmental trajectories when applicable

• Validation strategies:

  • Confirm computational predictions with targeted experiments

  • Use orthogonal techniques to validate key findings

  • Apply genetic perturbation to test causality of identified relationships

• Visualization and sharing:

  • Create integrated visualizations that communicate multi-dimensional findings

  • Deposit datasets in appropriate repositories with detailed metadata

  • Develop reproducible analysis pipelines for community use