PPP2R5A Antibody

What is PPP2R5A and why is it significant in research?

PPP2R5A is one of the regulatory subunits of protein phosphatase 2A (PP2A), a major serine/threonine phosphatase in cells. This protein is significant because it regulates the cellular location, substrate specification, and phosphatase function of PP2A . Through these mechanisms, PPP2R5A plays crucial roles in numerous cellular activities including cell cycle regulation, DNA damage response, and signal transduction pathways. Research shows that PPP2R5A is involved in regulating critical pathways including P53, Bcl-2, CDK, MAPK, JAK/STAT, c-Myc, and β-Catenin signaling . Its dysregulation has been implicated in various diseases, particularly several types of cancer, making it an important research target.

Which applications are most reliable for PPP2R5A antibody detection?

Based on validated research applications, Western Blotting (WB) has proven to be the most consistently reliable technique for PPP2R5A antibody detection across different antibody products. Most commercially available antibodies show strong performance in WB with dilution ranges typically between 1:300-1:10000 . For more comprehensive analyses:

When selecting an antibody for a specific application, researchers should verify the validation data for their particular application and target species .

How should researchers select the optimal PPP2R5A antibody epitope for functional studies?

The selection of an optimal epitope depends on the specific research question and experimental design. For functional studies investigating PPP2R5A's role in protein-protein interactions or signaling cascades, antibodies targeting functional domains are recommended. Based on available literature:

• N-terminal region antibodies (AA 1-50): Suitable for studying regulatory interactions as this region contains numerous phosphorylation sites that modulate PPP2R5A activity .

• Central domain antibodies (AA 107-156): Ideal for investigating the core functional properties of PPP2R5A as this region contains highly conserved sequences across species (100% identity in many vertebrates) .

• C-terminal region antibodies: Appropriate for studying substrate binding interactions.

For comprehensive studies examining PPP2R5A in ATM/ATR signaling pathways, antibodies targeting the full-length protein (AA 1-486) have been successfully employed in co-immunoprecipitation studies that verified interactions between PPP2R5A and ATM/ATR .

What controls are essential when validating PPP2R5A antibody specificity?

Rigorous validation of antibody specificity requires multiple complementary controls:

• Positive tissue/cell controls: Human ileum tissue, HeLa cells, and brain tissue have shown reliable PPP2R5A expression . For cross-species studies, heart tissue from human, mouse, and rat has demonstrated consistent reactivity.

• Negative controls:

  • Primary antibody omission

  • Non-specific IgG from the same host species

  • Pre-absorption with immunizing peptide

• Genetic controls (gold standard):

  • PPP2R5A knockdown/knockout validation: RNA interference or CRISPR/Cas9 approaches to reduce or eliminate target expression

  • Overexpression of tagged PPP2R5A constructs to confirm antibody reactivity with the target protein

• Cross-reactivity assessment: Especially important when working with PPP2R5 family members (PPP2R5A-E) which share significant sequence homology. Western blot analysis should show distinct molecular weights corresponding to each family member .

How can researchers differentiate between PPP2R5A isoforms and closely related family members?

Differentiating between PPP2R5 family members (PPP2R5A-E) is technically challenging due to sequence similarities. A methodological approach includes:

• Epitope selection: Use antibodies targeting unique regions. For example, mutations at positions I31 and I128 in viral proteins have been shown to selectively affect PPP2R5A compared to other family members , indicating these regions may contain distinctive sequences.

• Molecular weight discrimination: While PPP2R5A has a predicted molecular weight of 56 kDa, actual observed weights range from 50-56 kDa . Create a reference table of expected molecular weights for each family member on your gel system.

• Isoform-specific targeting: When working with PPP2R5A, consider these validation steps:

  • Use recombinant PPP2R5A-E proteins as positive controls

  • Perform parallel knockdown experiments of individual family members

  • Employ RT-PCR with isoform-specific primers as complementary validation

• Multi-antibody approach: Utilize multiple antibodies targeting different epitopes to confirm specificity through pattern consistency.

What are the optimal sample preparation methods for detecting PPP2R5A in different subcellular fractions?

The detection of PPP2R5A across subcellular compartments requires tailored sample preparation approaches:

• Total cellular protein extraction:

  • Standard RIPA buffer with protease inhibitors works well for most applications

  • Include phosphatase inhibitors (sodium fluoride, sodium orthovanadate) to preserve phosphorylation states when studying PPP2R5A regulatory functions

• Nuclear fraction enrichment:

  • Use hypotonic buffer followed by nuclear lysis buffer

  • Critical for studying PPP2R5A's role in ATM/ATR signaling and DNA damage response

• Cytoplasmic fraction:

  • Low-detergent buffers that preserve cytoskeletal associations

  • Important for examining PPP2R5A's interaction with translation factors like eIF3a

• Membrane-associated fraction:

  • Detergent-resistant membrane preparations

  • Relevant for investigating PPP2R5A's role in membrane-proximal signaling events

Optimization tip: When studying PPP2R5A's role in DNA damage response pathways, timing of sample collection is critical. Research shows dynamic changes in PPP2R5A activity following DNA damage induction, with peak interactions with ATM/ATR occurring during repair processes .

How does PPP2R5A expression and function affect cancer cell sensitivity to chemotherapeutic agents?

Research demonstrates that PPP2R5A plays a significant role in modulating cancer cell responses to DNA-damaging chemotherapeutic agents, particularly irinotecan. Key findings include:

• PPP2R5A levels inversely correlate with chemosensitivity:

  • Silencing PPP2R5A significantly increases cellular sensitivity to irinotecan in colorectal cancer cell lines (HT29, Caco2)

  • Conversely, PPP2R5A overexpression confers resistance to irinotecan treatment

• Mechanism of PPP2R5A-mediated chemoresistance:

  • PPP2R5A directly dephosphorylates and deactivates p-ATM and p-ATR signaling

  • Co-immunoprecipitation assays confirm direct interaction between PPP2R5A and ATM/ATR proteins

  • In normal DNA damage response, PPP2R5A helps terminate repair signaling once damage is resolved

  • When PPP2R5A is suppressed, prolonged ATM/ATR activation occurs, altering cell cycle checkpoints and DNA repair dynamics

• Translational regulation by eIF3a:

  • The translation initiation factor eIF3a translationally inhibits PPP2R5A expression

  • This eIF3a-PPP2R5A-ATM/ATR axis represents a novel regulatory pathway in DNA damage response

These findings suggest PPP2R5A may serve as a biomarker for predicting chemotherapy response and potentially as a therapeutic target to enhance chemosensitivity in resistant tumors.

What is the role of PPP2R5A in viral pathogenesis, particularly in HIV infection?

Research has revealed an unexpected relationship between PPP2R5A and viral pathogenesis, particularly with HIV-1:

• HIV-1 Vif-mediated degradation of PPP2R5A:

  • HIV-1 viral infectivity factor (Vif) protein targets PPP2R5 family proteins for degradation

  • This Vif-mediated degradation occurs independently of its well-known role in APOBEC3 antagonism

  • Specific amino acid residues (I31, I128) in Vif selectively regulate PPP2R5 degradation

• Functional consequences in cell cycle regulation:

  • Degradation of PPP2R5 family proteins by HIV-1 Vif leads to G2/M cell cycle arrest

  • This may represent a viral strategy to optimize cellular conditions for viral replication

• Evolutionary conservation:

  • Analysis of HIV-1 Vif variants shows covariation at positions 31 and 128, suggesting selective pressure to maintain PPP2R5 degradation capability

  • This conservation implies the importance of this mechanism for viral fitness

This research identifies PPP2R5A as a target in host-pathogen interactions and suggests potential new avenues for antiviral therapeutic development.

What methodological approaches can resolve contradictory findings when using different PPP2R5A antibodies?

Researchers often encounter contradictory results when using different antibodies against the same target. For PPP2R5A, a systematic troubleshooting approach includes:

• Epitope mapping comparison:

  • Document the exact binding regions of each antibody (e.g., AA 1-486, AA 107-156, etc.)

  • Determine if post-translational modifications might affect epitope recognition

  • Consider if protein-protein interactions could mask certain epitopes

• Validation with orthogonal techniques:

  • Complement antibody-based detection with mRNA expression analysis

  • Use mass spectrometry for unbiased protein identification

  • Employ CRISPR/Cas9 gene editing to create true negative controls

• Cross-validation with multiple antibodies:

  • Use antibodies from different host species targeting different epitopes

  • Create a concordance table to identify consistent vs. discordant findings

• Context-dependent expression:

  • Test if contradictory findings relate to cell/tissue type differences

  • Investigate if physiological stimuli alter PPP2R5A detection

  • Consider the timing of sample collection in response to treatments

In one relevant example from the literature, researchers investigating PPP2R5A interactions with ATM/ATR first validated antibody specificity through knockdown experiments before using the antibodies for co-immunoprecipitation studies. This multi-level validation approach ensured reliable interpretation of protein-protein interaction data .

How can researchers effectively study the dynamic regulatory interactions between PPP2R5A and ATM/ATR signaling pathways?

Studying the dynamic interactions between PPP2R5A and ATM/ATR signaling requires sophisticated experimental approaches:

• Temporal analysis of interactions:

  • Time-course experiments capturing the kinetics of PPP2R5A-ATM/ATR associations

  • Example protocol: Treat cells with DNA damaging agents (e.g., irinotecan) for 1 hour, then monitor recovery at multiple timepoints (0, 2, 4, 8, 24 hours)

  • Western blotting for phosphorylated forms of ATM (p-ATM) and ATR (p-ATR) with simultaneous PPP2R5A detection

• Proximity-based interaction assays:

  • Proximity ligation assay (PLA) to visualize PPP2R5A-ATM/ATR interactions in situ

  • FRET/BRET approaches using fluorescently tagged proteins

  • BioID or APEX2 proximity labeling to identify the broader PPP2R5A interaction network

• Phosphatase activity measurements:

  • In vitro phosphatase assays with immunoprecipitated PPP2R5A-containing complexes

  • Phospho-specific substrate analysis before and after PPP2R5A manipulation

  • Phosphoproteomic analysis to comprehensively assess PPP2R5A-dependent dephosphorylation events

• Genetic manipulation strategies:

  • Domain-specific mutations in PPP2R5A to dissect interaction surfaces

  • Expression of phosphomimetic or phospho-deficient variants of interaction partners

  • Inducible expression/depletion systems to control the timing of PPP2R5A perturbation

Research demonstrates that PPP2R5A directly regulates ATM/ATR signaling through dephosphorylation, with significant implications for DNA damage responses and chemotherapeutic sensitivity. When PPP2R5A is silenced, prolonged activation of ATM/ATR and increased γ-H2AX formation are observed, indicating persistent DNA damage signaling .

How can PPP2R5A antibodies be effectively employed in translational research for cancer biomarker development?

Emerging translational applications for PPP2R5A antibodies in cancer research include:

• Prognostic biomarker development:

  • IHC-based tissue microarray analysis of PPP2R5A expression across tumor types

  • Correlation with patient outcomes and treatment responses

  • Multi-parameter analysis alongside other PP2A subunits and ATM/ATR pathway components

• Predictive biomarker for chemotherapy response:

  • Research indicates PPP2R5A levels predict sensitivity to irinotecan

  • Standardized IHC or WB protocols could provide clinically applicable methods

  • Potential for companion diagnostic development

• Monitoring therapy-induced changes:

  • Serial liquid biopsy analysis of PPP2R5A in circulating tumor cells

  • Correlation with treatment response and resistance development

  • Integration with other DNA damage response markers

• Combination therapy rationale:

  • Identification of synergistic drug combinations targeting the eIF3a-PPP2R5A-ATM/ATR axis

  • Screening for compounds that modulate PPP2R5A expression or activity

  • Development of pharmacodynamic markers for clinical trials

A methodological framework for implementing PPP2R5A as a biomarker would include standardization of antibody-based detection methods, establishment of scoring systems for expression levels, and prospective validation in patient cohorts.

What are the most promising approaches for studying PPP2R5A's substrate specificity and regulatory networks?

Advanced approaches for investigating PPP2R5A's substrate specificity and regulatory networks include:

• Systems-level phosphoproteomics:

  • Quantitative phosphoproteomic analysis comparing wild-type vs. PPP2R5A-depleted cells

  • Dynamic phosphoproteomics following stimulus (e.g., DNA damage, growth factor signaling)

  • Computational modeling of phosphorylation/dephosphorylation networks

• Structural biology approaches:

  • Cryo-EM or X-ray crystallography of PPP2R5A-containing PP2A holoenzymes

  • Molecular dynamics simulations of substrate recruitment and catalysis

  • Structure-guided mutagenesis to validate interaction surfaces

• Proximity-dependent labeling coupled with mass spectrometry:

  • BioID, TurboID, or APEX2 fusion proteins to identify PPP2R5A proximal interactors

  • Identification of context-dependent interactions across different cellular compartments

  • Validation of novel interactors using co-immunoprecipitation with carefully validated antibodies

• Transcriptional and translational regulation analysis:

  • Investigation of mechanisms controlling PPP2R5A expression

  • Further exploration of the eIF3a-mediated translational control

  • Analysis of how these regulatory mechanisms are altered in disease states