PPIL3 Antibody

What is PPIL3 and what is its biological significance?

PPIL3 (Peptidylprolyl Isomerase Cyclophilin-Like 3), also known as Cyclophilin J (CyPJ), belongs to the cyclophilin family of peptidyl-prolyl cis-trans isomerases. These enzymes catalyze the cis-trans isomerization of proline imidic peptide bonds in oligopeptides, a rate-limiting step in protein folding . PPIL3 accelerates protein folding and may function as a molecular chaperone .

The protein has been implicated in pre-mRNA splicing mechanisms , and is notably associated with cyclophilin B through their overlapping functions in protein folding and transport pathways. Impairment of these functions has been linked to neurodegenerative disorders . Additionally, research has demonstrated that PPIL3 can interact with Apoptin, a protein from chicken anemia virus that selectively induces cell death in cancer cells, affecting its cellular localization .

What types of PPIL3 antibodies are commercially available for research applications?

Based on the available literature, researchers can access a diverse range of PPIL3 antibodies suitable for various experimental applications:

What are the standard applications for PPIL3 antibodies in molecular and cellular research?

PPIL3 antibodies have been validated for multiple experimental applications:

• Western Blotting (WB): Most PPIL3 antibodies are validated for WB, with the predicted band size at 18 kDa . Recommended dilutions vary by product, typically ranging from 0.04-0.4 μg/mL to 1/500 .

• Immunohistochemistry (IHC): Several antibodies are applicable for both paraffin-embedded (IHC-P) and frozen tissue sections. Dilutions typically range from 1:50-1:200 . Expression patterns have been documented in various tissues including stomach and urinary bladder cancer cell lines .

• Immunocytochemistry/Immunofluorescence (ICC/IF): Used for cellular localization studies, with recommended concentrations around 0.25-2 μg/mL or 4 μg/ml .

• Flow Cytometry (FACS): Some monoclonal antibodies are specifically validated for flow cytometry applications .

• ELISA: Select antibodies have been validated for this application, particularly those with high sensitivity thresholds .

How should researchers select the optimal PPIL3 antibody for specific experimental applications?

When selecting a PPIL3 antibody, consider these critical parameters:

Target Region Selection:

• C-terminal antibodies (AA 118-146) are widely used for general detection

• Middle region antibodies may provide alternative epitope recognition

• N-terminal region antibodies (AA 1-53) are available as control fragments

Clonality Considerations:

• Polyclonal antibodies offer broader epitope recognition but potentially higher background

• Monoclonal antibodies provide consistent lot-to-lot reproducibility and higher specificity

Species Reactivity Assessment:

• Human reactivity is consistently validated across most antibodies

• Cross-reactivity with mouse and rat samples varies by product and should be experimentally confirmed

• Some antibodies claim broad cross-reactivity with multiple species

Application-Specific Selection:

• For cellular localization studies, prefer antibodies validated for ICC/IF with fluorescent conjugates

• For tissue expression analysis, select antibodies with demonstrated IHC performance

• For quantitative analysis, choose antibodies validated for ELISA or FACS applications

Validation Evidence:

• Review available immunoblot images showing the expected 18 kDa band

• Examine IHC/ICC images for appropriate subcellular localization patterns

• Consider antibodies cited in peer-reviewed publications

What methodological approaches are recommended for optimizing Western blot protocols with PPIL3 antibodies?

Sample Preparation Optimization:

• Extract proteins from tissues or cell lines with documented PPIL3 expression (e.g., human fetal brain, human fetal liver , A431 cells , RT4 cells )

• Include protease inhibitors to prevent degradation of the 18 kDa PPIL3 protein

• Denature samples thoroughly given PPIL3's role in protein folding

Electrophoresis and Transfer Parameters:

• Use 12-15% polyacrylamide gels to optimize resolution of the 18 kDa PPIL3 protein

• Employ semi-dry or wet transfer methods with PVDF membranes for optimal protein binding

• Verify transfer efficiency with reversible staining methods

Antibody Incubation Protocol:

• Block membranes with 5% non-fat milk or BSA in TBST for 1 hour at room temperature

• Dilute primary antibodies according to manufacturer recommendations:

  • For polyclonal antibodies: typically 1/500 or 0.04-0.4 μg/mL

  • For monoclonal antibodies: follow specific product guidelines

• Incubate membranes overnight at 4°C with gentle agitation

• Wash extensively (4-5 times, 5 minutes each) with TBST before secondary antibody incubation

Detection and Validation:

• Use appropriate secondary antibodies conjugated to HRP, fluorescent tags, or other detection systems

• Include positive controls (human fetal brain lysate, human fetal liver lysate )

• Verify specificity with recombinant PPIL3 protein controls

• Expected band size should be approximately 18 kDa

What approaches can enhance immunohistochemistry and immunofluorescence experiments using PPIL3 antibodies?

Tissue Preparation and Fixation:

• For paraffin-embedded tissues, use 10% neutral buffered formalin fixation

• For frozen sections, fix with 4% paraformaldehyde to preserve epitope accessibility

• Consider epitope retrieval methods (heat-induced or enzymatic) based on the specific antibody requirements

Staining Protocol Optimization:

• Block endogenous peroxidase activity (for IHC) using 0.3% hydrogen peroxide

• Implement protein blocking with 5-10% normal serum from the species of the secondary antibody

• Apply primary antibody at validated dilutions:

  • For IHC-P: typically 1:50-1:200

  • For ICC/IF: approximately 0.25-2 μg/mL or 4 μg/ml

• Incubate sections overnight at 4°C in a humidified chamber

• Use appropriate detection systems (HRP-DAB for IHC, fluorescent-conjugated secondaries for IF)

Controls and Validation:

• Include positive control tissues with known PPIL3 expression (e.g., human stomach )

• Implement negative controls (omitting primary antibody, isotype controls)

• Consider using recombinant PPIL3 fragment controls for blocking experiments

• Validate staining patterns against existing literature and database resources

Troubleshooting Guidelines:

• For high background: increase blocking time/concentration, optimize antibody dilutions

• For weak signal: adjust antigen retrieval methods, increase antibody concentration or incubation time

• For non-specific staining: implement additional washing steps, use more stringent blocking conditions

• For mouse-on-mouse background: consider using specialized blocking reagents when using mouse antibodies on mouse tissues

How do PPIL3 antibodies perform across different species and what cross-reactivity considerations should researchers address?

Species Reactivity Profile:
The majority of PPIL3 antibodies are primarily validated against human samples, but cross-reactivity varies significantly:

Cross-Reactivity Management Strategies:

• Perform preliminary validation studies when using antibodies on non-human species

• Consider sequence homology analysis between human PPIL3 and the target species

• Include appropriate positive and negative controls specific to the species being studied

• When working with mouse antibodies on mouse tissues, implement mouse-on-mouse blocking strategies

• For critical cross-species applications, consider using antibodies raised against conserved epitopes (e.g., those targeting amino acids with 98% homology between human, mouse, and rat )

Species-Specific Optimization:

• For human samples: Most antibodies are well-validated across multiple applications

• For mouse/rat samples: Verify antibody performance with preliminary experiments, particularly when only "predicted reactivity" is claimed

• For other species: Consider custom antibody generation if commercial options lack validation

What strategies should be employed to validate PPIL3 antibodies for research applications?

Comprehensive Validation Framework:

• Genetic Approaches:

  • Compare antibody staining between wild-type samples and PPIL3 knockout models

  • Utilize PPIL3 siRNA knockdown to confirm signal reduction in proportion to protein depletion

  • Overexpress tagged PPIL3 constructs to verify co-localization with antibody staining

• Biochemical Validation:

  • Perform peptide competition assays using recombinant PPIL3 fragments

  • For blocking experiments, use a 100x molar excess of protein fragment control based on concentration and molecular weight

  • Pre-incubate antibody-protein control fragment mixture for 30 minutes at room temperature

  • Compare western blot results with predicted molecular weight (18 kDa)

• Orthogonal Detection Methods:

  • Correlate antibody-based detection with mRNA expression data

  • Compare results across multiple antibodies targeting different PPIL3 epitopes

  • Validate findings with alternative techniques (mass spectrometry, RNA-seq)

• Application-Specific Validation:

  • For WB: Verify single band at expected molecular weight (18 kDa)

  • For IHC/ICC: Confirm appropriate subcellular localization patterns

  • For IP: Demonstrate enrichment of target protein with subsequent mass spectrometry verification

• Lot-to-Lot Consistency Assessment:

  • Implement standardized positive controls for each new antibody lot

  • Document and compare staining patterns, band intensities, and background levels

How do different epitope regions of PPIL3 antibodies affect experimental outcomes and interpretation?

Epitope Mapping Analysis:

PPIL3 antibodies target distinct regions of the 161-amino acid protein, each with potential implications for experimental outcomes:

Functional Implications of Epitope Selection:

• Protein-Protein Interaction Studies:

  • Antibodies targeting regions involved in the Apoptin interaction (implicated in cytoplasmic localization ) may interfere with or detect changes in this interaction

  • When studying PPIL3's association with cyclophilin B , epitope accessibility may be affected by complex formation

• Isoform Detection:

  • PPIL3 has multiple transcript variants (e.g., PPIL3b mentioned in result )

  • Antibodies targeting conserved regions can detect multiple isoforms

  • Isoform-specific detection requires epitopes in unique regions

• Post-translational Modification Sensitivity:

  • Antibodies targeting regions subject to phosphorylation or other modifications may show differential reactivity

  • Consider whether the experimental question requires detection of modified or unmodified forms

• Structural Conformation Considerations:

  • Given PPIL3's role in protein folding, its own conformational states may affect epitope accessibility

  • Native versus denatured conditions may yield different results depending on epitope location

What methodological approaches can be used to investigate PPIL3's protein-protein interactions using antibody-based techniques?

Co-Immunoprecipitation Strategies:

• Standard Co-IP Protocol for PPIL3 Interaction Partners:

  • Lyse cells under non-denaturing conditions to preserve protein-protein interactions

  • Pre-clear lysates with appropriate control beads/antibodies

  • Immunoprecipitate with anti-PPIL3 antibodies (consider epitope location relative to interaction sites)

  • Analyze precipitated complexes by western blotting for potential interacting partners

• Reciprocal Co-IP Validation:

  • Perform reverse immunoprecipitation with antibodies against suspected interacting partners

  • Blot for PPIL3 to confirm interaction bidirectionally

  • Include appropriate negative controls (isotype-matched antibodies, irrelevant targets)

Proximity Ligation Assay (PLA) Implementation:

• PLA Protocol for PPIL3 Interactions:

  • Fix cells while preserving native protein conformations

  • Apply primary antibodies against PPIL3 and suspected interacting partners

  • Implement PLA secondary antibodies and detection reagents

  • Analyze fluorescent signals indicating protein proximity (<40 nm)

PPIL3-Apoptin Interaction Analysis:

Based on research findings , PPIL3 interacts with Apoptin and affects its cellular localization:

• Localization Studies Protocol:

  • Transfect cells with Apoptin constructs

  • Modulate PPIL3 levels through overexpression or knockdown

  • Immunostain for both proteins to assess co-localization patterns

  • Analyze whether PPIL3 maintains Apoptin in the cytoplasm as reported

• Interaction Domain Mapping:

  • Generate PPIL3 truncation mutants targeting different functional domains

  • Assess their ability to interact with Apoptin

  • Focus on the P109A mutant region, which has been shown to significantly impair Ppil3 function

Cyclophilin B-PPIL3 Association Studies:

Given the reported association between PPIL3 and cyclophilin B in protein folding and transport :

• Co-localization Analysis Protocol:

  • Perform double immunofluorescence staining for PPIL3 and cyclophilin B

  • Analyze subcellular distribution patterns in normal versus stressed conditions

  • Quantify co-localization coefficients using appropriate imaging software

• Functional Association Assessment:

  • Design experiments to measure protein folding efficiency with modulated levels of PPIL3 and cyclophilin B

  • Utilize stress conditions to examine potential cooperative roles in preventing protein misfolding

  • Investigate implications for neurodegenerative disorders where protein folding is compromised