SPS100 Antibody

What is SP100 and what is its primary cellular function?

SP100 is a nuclear antigen and major component of the PML (promyelocytic leukemia)-SP100 nuclear bodies. It functions in the control of gene expression and plays significant roles in tumorigenesis, immunity, and gene regulation. The protein contains a HSR domain crucial for nuclear body targeting and dimerization, as well as a PxVxL motif required for interaction with chromoshadow domains. SP100 is covalently modified by the SUMO-1 modifier, which is considered essential for nuclear body interactions . The protein binds heterochromatin proteins and is thought to function as a tumor suppressor. Together with PML, it constitutes a major component of PML bodies, which are subnuclear organelles involved in numerous physiological processes including cell growth regulation .

What are the key characteristics of SP100 antibodies used in research?

SP100 antibodies used in research are primarily available as rabbit or mouse-derived reagents with various specifications. For example, recombinant monoclonal antibodies offer batch-to-batch consistency, easy scale-up, and future security of supply . The key specifications include:

The antibodies are often available in conjugation-ready formats (PBS only, BSA and azide free) that make them ideal for various applications including ELISAs, multiplex assays, mass cytometry, and multiplex imaging .

How does SP100 differ from SPS100, and why is this distinction important for researchers?

This is a critical distinction for researchers to understand. SP100 refers to human SP100 nuclear antigen (Gene ID: 6672), a component of nuclear bodies involved in gene expression regulation . In contrast, SPS100 refers to a protein from Saccharomyces cerevisiae (Baker's yeast) with different structure and function .

When designing experiments, researchers must ensure they're using the appropriate antibody for their target organism. Using an antibody raised against human SP100 in yeast studies (or vice versa) would likely result in non-specific binding or false negatives. The antibodies have different immunogens, reactivity profiles, and applications:

• SP100 antibodies: Typically react with human, mouse, or rat SP100; used in cancer, epigenetics, nuclear signaling, and immunology research

• SPS100 antibodies: React with Saccharomyces cerevisiae; primarily used in yeast research applications

This distinction becomes particularly important when ordering research materials, designing experimental controls, and interpreting cross-reactivity in multi-species studies.

What are the optimal conditions for using SP100 antibody in Western blotting?

For Western blotting applications with SP100 antibody, researchers should consider the following methodological approach:

• Sample preparation: Due to SP100's nuclear localization, ensure effective nuclear extraction protocols.

• Dilution range: Typically 1:500-1:2000 for polyclonal antibodies . Recombinant monoclonal antibodies may require optimization.

• Expected bands: Look for bands between 70-100 kDa, as SP100 has a calculated molecular weight of 100 kDa but shows aberrant electrophoretic mobility in SDS-PAGE (observed at 70-100 kDa) .

• Controls: Include positive controls from cell lines known to express SP100 (e.g., various human cell lines).

• Blocking: Standard BSA or milk-based blocking solutions are generally effective.

• Verification: Consider validating with multiple antibodies targeting different epitopes of SP100 to confirm specificity.

For polyclonal antibodies, optimization of incubation times and washing steps may be particularly important to reduce background. The aberrant electrophoretic mobility of SP100 is a key consideration when interpreting results, as it may appear at different molecular weights than expected .

How can SP100 antibody be effectively utilized in immunohistochemistry studies?

For effective immunohistochemistry applications with SP100 antibody, researchers should follow these methodological guidelines:

• Tissue preparation: Use formalin-fixed, paraffin-embedded (FFPE) sections with appropriate antigen retrieval methods.

• Antigen retrieval: Heat-induced epitope retrieval using basic pH buffers is generally effective for nuclear antigens.

• Antibody concentration: Start with 5 μg/mL and optimize based on signal-to-noise ratio.

• Detection system: HRP-polymer detection systems work well for visualizing SP100, which appears as nuclear dots.

• Counterstaining: Hematoxylin provides good contrast to visualize nuclear localization.

• Pattern interpretation: Look for nuclear dot patterns, which are characteristic of SP100 and distinct from the nuclear envelope pattern seen with gp210 antibodies .

When analyzing IHC results, SP100 staining should be evaluated for the characteristic multiple nuclear dots pattern, which is specific for anti-SP100 antibodies. This pattern can be visualized in various cell types, including stellate cells in cerebellum as observed with related S100 protein antibodies .

What are the validated protocols for using SP100 antibody in ELISA-based assays?

For ELISA applications with SP100 antibody, researchers can employ several validated approaches:

• Sandwich ELISA: Use matched antibody pairs such as MP00964-4 (84012-6-PBS for capture and 84012-1-PBS for detection) .

• Cytometric bead array: Another validated approach uses MP00964-1 (84012-4-PBS for capture and 84012-2-PBS for detection) .

• Semi-quantitative detection: Commercial kits use purified peptides corresponding to a portion of the SP100 protein bound to polystyrene microwell plates .

• Protocol outline:

  • Coat plates with capture antibody (1 μg/mL)

  • Block with appropriate blocking buffer

  • Add samples and standards

  • Add detection antibody

  • Add enzyme conjugate

  • Develop with substrate and measure optical density

The semi-quantitative detection of anti-SP100 antibodies of the IgG class in human serum follows a specific methodology: pre-diluted controls and diluted patient sera are added to wells with immobilized SP100 antigen, followed by washing and addition of enzyme-labeled anti-human IgG conjugate. After incubation, the enzyme-labeled antibodies bind to patient antibodies attached to the microwells, allowing for colorimetric detection .

What is the significance of SP100 antibodies in primary biliary cholangitis (PBC) diagnosis?

SP100 antibodies have substantial clinical significance in the diagnosis of primary biliary cholangitis (PBC), particularly in anti-mitochondrial antibody (AMA) negative cases. The methodological approach to utilizing SP100 antibodies in PBC diagnosis includes:

• Diagnostic algorithm: SP100 antibody testing is a first-line test when PBC is strongly suspected, particularly in conjunction with AMA and GP210 antibody testing .

• AMA-negative cases: Of particular importance, approximately 20% of AMA-negative PBC patients are SP100-positive, making this antibody a valuable diagnostic marker when the primary biomarker is absent .

• Interpretation alongside other markers: SP100 antibodies should be evaluated alongside antinuclear antibodies (ANA), which are positive in 45% of AMA-negative cases .

• Clinical correlation: SP100-positive PBC patients demonstrate distinct biochemical profiles, including significantly higher levels of:

  • Alkaline phosphatase (ALP): 466 U/L vs. 163 U/L in SP100-negative patients

  • Gamma-glutamyl-transpeptidase (GGT): 728 U/L vs. 154 U/L in SP100-negative patients

  • Immunoglobulin M (IgM): 4.25±2.86 vs. 2.81±2.15 in SP100-negative patients

How do SP100 antibody expression patterns correlate with different disease states and demographic factors?

Research has revealed important correlations between SP100 antibody expression patterns and various disease parameters:

• Gender distribution: SP100-positive PBC demonstrates a bias toward female patients (80.0% vs. 61.9% in SP100-negative PBC), although this did not reach statistical significance in all studies .

• Age correlation: No significant difference in age has been observed between SP100-positive and SP100-negative patients (51.6±9.5 vs. 50.0±14.7 years) .

• Symptomatology: SP100-positive patients may have a higher proportion of atypical symptoms (18.2% vs. 13.8%), though this difference has not reached statistical significance in all studies .

• Laboratory markers: As noted above, SP100-positive status correlates with significantly elevated ALP, GGT, and IgM levels, suggesting a distinct biochemical phenotype .

What emerging research areas are utilizing SP100 antibodies beyond traditional applications?

Recent research has expanded the applications of SP100 antibodies beyond traditional diagnostic uses:

• Multiplex imaging applications: Conjugation-ready antibody formats are enabling advanced multiplex imaging to study SP100 in the context of other nuclear body components .

• Mass cytometry: The availability of conjugation-ready formats has facilitated incorporation of SP100 antibodies into mass cytometry panels for high-dimensional single-cell analysis .

• Epigenetic research: SP100's role in binding heterochromatin and gene regulation has sparked interest in epigenetic studies examining its interactions with chromatin modifiers .

• Cancer research: Given SP100's tumor suppressor activity, antibodies are being used to investigate its role in various malignancies .

• Differential diagnosis: Implementation in multianalyte test panels to distinguish PBC from other autoimmune liver diseases .

The development of recombinant monoclonal antibodies with high batch-to-batch consistency is particularly enabling for these emerging applications, which often require highly reproducible reagents for quantitative analyses and longitudinal studies .

What factors should researchers consider when selecting between monoclonal and polyclonal SP100 antibodies?

The selection between monoclonal and polyclonal SP100 antibodies requires careful consideration of several experimental factors:

The emerging recombinant monoclonal antibodies offer advantages of both specificity and consistency, making them increasingly preferred for quantitative applications and longitudinal studies requiring reliable reproducibility .

How can researchers troubleshoot abnormal electrophoretic mobility of SP100 in Western blot applications?

The abnormal electrophoretic mobility of SP100 presents a common challenge in Western blot applications that requires methodical troubleshooting:

• Understand expected patterns: SP100 has a calculated molecular weight of 100 kDa but typically appears at 70-100 kDa on SDS-PAGE due to its aberrant mobility .

• Optimize sample preparation:

  • Use fresh protease inhibitors during extraction

  • Consider phosphatase inhibitors, as post-translational modifications may affect mobility

  • Test different lysis buffers optimized for nuclear proteins

• Adjust electrophoresis conditions:

  • Use gradient gels (4-12% or 4-15%) to better resolve the range of 70-100 kDa

  • Modify running buffer ionic strength and pH

  • Consider native PAGE to preserve protein complexes if relevant

• Confirmation strategies:

  • Run known positive controls alongside experimental samples

  • Use multiple antibodies targeting different epitopes of SP100

  • Consider mass spectrometry validation of bands if critical for your research

• Account for splice variants: SP100 has multiple splice variants (including high-mobility group protein variants) that may appear at different molecular weights .

This aberrant mobility is a characteristic feature of SP100 rather than a technical artifact, likely resulting from its acidic nature and post-translational modifications .

What are the critical considerations for optimizing SP100 antibody use in multiplex imaging and mass cytometry?

For advanced applications like multiplex imaging and mass cytometry with SP100 antibodies, researchers should consider these critical optimization parameters:

• Antibody preparation for conjugation:

  • Use conjugation-ready formats (PBS only, BSA and azide free) to avoid interference with conjugation chemistry

  • Optimize antibody:fluorophore or antibody:metal ratios to prevent over-conjugation

  • Validate conjugated antibodies against unconjugated versions to ensure epitope recognition is preserved

• Panel design considerations:

  • Select compatible fluorophores or metal isotopes that minimize spectral overlap

  • Include appropriate isotype controls conjugated with the same fluorophore/metal

  • Consider the relative abundance of SP100 versus other targets when balancing panel brightness

• Protocol adjustments:

  • Optimize permeabilization protocols to ensure nuclear accessibility

  • Extend incubation times for nuclear targets compared to surface markers

  • Test fixation methods to preserve nuclear morphology while maintaining epitope accessibility

• Analysis strategies:

  • Use proper compensation/unmixing algorithms for fluorescence-based systems

  • Implement appropriate gating strategies that account for the nuclear dot pattern of SP100

  • Consider dimensionality reduction techniques (tSNE, UMAP) for visualizing complex relationships between SP100 and other markers

These advanced applications benefit significantly from the batch-to-batch consistency of recombinant monoclonal antibodies, which enables reliable quantitative comparisons across experiments and time points .

How do storage conditions and handling procedures affect SP100 antibody performance?

Proper storage and handling of SP100 antibodies is critical for maintaining their performance characteristics:

• Storage temperature requirements:

  • Conjugation-ready formats: Store at -80°C to maintain conjugation efficiency and prevent degradation

  • Standard antibody preparations: Store at -20°C or -80°C according to manufacturer recommendations

  • Avoid repeated freeze-thaw cycles which can lead to aggregation and loss of activity

• Buffer composition effects:

  • PBS-only formats (BSA and azide free) are designed for conjugation applications but may have reduced stability during extended storage

  • Glycerol-containing formulations (typically 50% glycerol) provide better stability during freeze-thaw cycles

  • Preservatives like 0.03% Proclin 300 help prevent microbial contamination without interfering with common applications

• Aliquoting strategy:

  • Upon receipt, prepare small single-use aliquots to avoid repeated freeze-thaw cycles

  • Calculate volumes based on dilution requirements for different applications

  • Use screw-cap cryovials to prevent evaporation during long-term storage

• Shipping considerations:

  • Verify antibody activity after shipment, particularly if any temperature excursions occurred

  • Allow frozen antibodies to thaw completely at 4°C before opening to prevent condensation

Following these handling procedures is particularly important for maintaining the specificity and sensitivity of SP100 antibodies, especially for quantitative applications where consistent performance is essential .

What experimental controls are essential when working with SP100 antibodies in different research contexts?

Implementing appropriate controls is critical for ensuring reliable and interpretable results with SP100 antibodies:

• Essential negative controls:

  • Isotype controls: Include matched rabbit/mouse IgG at the same concentration as the primary antibody

  • Secondary-only controls: Omit primary antibody to assess background from secondary detection systems

  • Knockout/knockdown validation: When possible, use SP100 knockout or knockdown samples to confirm specificity

• Positive controls for different applications:

  • Western blot: Cell lines with confirmed SP100 expression (considering the 70-100 kDa observed molecular weight range)

  • IHC: Normal human tissues with known SP100 expression patterns (nuclear dot pattern)

  • ELISA: Calibrated reference standards for quantitative applications

• Application-specific considerations:

  • For clinical diagnostics: Include known positive and negative patient samples

  • For multiplex applications: Single-stained controls for compensation/unmixing

  • For fluorescence microscopy: Autofluorescence controls to distinguish true SP100 signal

• Cross-validation strategies:

  • Orthogonal method validation: Confirm key findings using multiple detection techniques

  • Multiple antibody validation: Use antibodies targeting different SP100 epitopes

  • Genetic validation: Correlate protein expression with mRNA levels when appropriate

These comprehensive control strategies help distinguish specific SP100 signals from technical artifacts, particularly important given the nuclear localization and distinct staining pattern of this protein .

What are the emerging methodologies for studying SP100 interaction with other nuclear body components?

Advanced research into SP100's role in nuclear bodies is employing several cutting-edge methodologies:

• Proximity labeling techniques:

  • BioID and TurboID approaches fused to SP100 to identify proximal proteins in living cells

  • APEX2-based proximity labeling for temporally controlled mapping of the SP100 interactome

  • These methods overcome limitations of traditional co-immunoprecipitation for studying dynamic nuclear body components

• Super-resolution microscopy:

  • STORM and PALM imaging to resolve substructures within SP100-containing nuclear bodies

  • Lattice light-sheet microscopy for live-cell dynamics of SP100 nuclear bodies

  • Expansion microscopy to physically magnify nuclear structures for improved resolution

• Mass spectrometry-based approaches:

  • Crosslinking mass spectrometry (XL-MS) to capture direct SP100 protein interactions

  • Thermal proteome profiling to identify proteins stabilized by SP100 interactions

  • Targeted proteomics to quantify stoichiometry of nuclear body components

• Functional genomics integration:

  • CRISPR screens targeting SP100 domains to identify functional interaction regions

  • Proteogenomic approaches correlating SP100 variants with interaction networks

  • Cell-type specific interaction mapping using conditional expression systems

These emerging approaches are revealing unprecedented details about how SP100 organizes and functions within nuclear bodies and how these structures respond to cellular stresses and signaling events .

How might SP100 antibodies contribute to personalized medicine approaches for autoimmune liver diseases?

SP100 antibodies show promising potential for advancing personalized medicine in autoimmune liver diseases:

• Stratification of PBC patients:

  • SP100 antibody status identifies a subset of patients with distinct biochemical profiles (higher ALP, GGT, IgM)

  • This stratification could inform treatment selection and monitoring protocols

  • Female patients with SP100-positive status may represent a distinct subgroup requiring tailored management

• Prediction of treatment response:

  • Ongoing research is investigating whether SP100 antibody levels correlate with response to ursodeoxycholic acid and second-line therapies

  • Serial monitoring of SP100 antibodies might provide early indicators of treatment efficacy

  • Integration with other biomarkers could generate predictive algorithms for treatment outcomes

• Early disease detection:

  • SP100 antibodies may appear before clinical manifestations, enabling earlier intervention

  • Screening high-risk populations (e.g., first-degree relatives of PBC patients) for SP100 antibodies could identify pre-clinical disease

  • Combining SP100 with other autoantibody markers improves diagnostic sensitivity

• Therapeutic target potential:

  • Understanding SP100's role in disease pathogenesis could identify new therapeutic targets

  • Blocking SP100-autoantibody interactions might represent a future therapeutic approach

  • Monitoring changes in SP100 expression patterns could serve as pharmacodynamic biomarkers

These approaches could transform management of PBC and related autoimmune liver diseases from a one-size-fits-all approach to personalized strategies based on molecular and immunological profiles .