Antibodies are Y-shaped glycoproteins composed of two heavy chains and two light chains (λ or κ), with a molecular weight of ~150 kDa for IgG isotypes . Their dual functionality—antigen binding (via the Fab fragment) and immune system activation (via the Fc region)—is critical for neutralizing pathogens and triggering immune responses .
The five immunoglobulin classes (IgG, IgM, IgA, IgE, IgD) differ in heavy chain composition and biological functions :
Monoclonal antibodies like bamlanivimab (targeting SARS-CoV-2 RBD) modulate memory B-cell responses, skewing epitope recognition and reducing long-term immune memory . This highlights the immunomodulatory potential of therapeutic antibodies .
Anti-PfCSP (Plasmodium falciparum circumsporozoite protein) antibodies, such as L9 and CIS43, neutralize sporozoites by binding repeat regions (NANP, NVDP) and junctional epitopes . Their efficacy in mouse models underscores the importance of epitope targeting in antibody design .
The O4 antibody (MAB1326) is used to identify oligodendrocyte precursors in rat cortical stem cells, enabling studies on myelination and neurodegeneration . Its specificity for sulfated galactocerebrosides highlights the role of glycolipid markers in neural research .
Cancer: Antibodies like rituximab (IgG1) target CD20+ B-cells, combining ADCC and CDC for lymphoma treatment .
Autoimmune Diseases: Engineered antibodies (e.g., adalimumab) block cytokine receptors (e.g., TNF-α), reducing inflammation .
Infectious Diseases: Anti-RSV antibodies (e.g., palivizumab) prevent hospitalization in high-risk infants .
Epitope Mapping: High-resolution studies of antibody-antigen complexes (e.g., PfCSP-L9 interactions ) are critical for rational vaccine design.
Glycoengineering: Modifying Fc glycosylation enhances ADCC/CDC activity, as seen in trastuzumab (HER2-targeting) .
Bispecific Antibodies: Dual-targeting formats (e.g., CD19xCD3) improve cancer immunotherapy efficacy .
KEGG: spo:SPAC3C7.04
STRING: 4896.SPAC3C7.04.1
SPAC3C7.04 is an uncharacterized transcriptional regulatory protein in Schizosaccharomyces pombe (fission yeast) that contains a fungal Zn(2)-Cys(6) binuclear cluster domain . This 783-amino acid protein is localized in both the nucleus and cytoplasm , functioning primarily in the regulation of transcription. Its significance stems from its role in gene-specific transcription from RNA polymerase II promoter and its potential involvement in cell cycle regulation .
Researchers interested in transcriptional networks in fission yeast find SPAC3C7.04 particularly intriguing because it has been identified as a potentially significant transcription factor with periodic activities during the cell cycle . Analysis of regulatory networks in S. pombe has shown that SPAC3C7.04 demonstrates significant activity (P-value 2.84E-15) with its fungal Zn(2)-Cys(6) binuclear cluster domain, suggesting it may play a key role in coordinating phase-specific gene expression .
While SPAC3C7.04 remains relatively uncharacterized, several studies have begun to elucidate its functions:
Cell Cycle Roles: Genetic interaction screens have revealed potential cell cycle functions for SPAC3C7.04, alongside other transcription factors like SPBC56F2.05 and SPCC320.03 .
Telomere Association: Research has shown that SPAC3C7.04 mutants have elongated telomeres, suggesting a potential role in telomere maintenance .
Transcriptional Regulation: Gene ontology analysis classifies it with specific RNA polymerase II transcription factor activity , placing it in important regulatory networks.
Periodic Expression: Global gene regulatory network analyses identified SPAC3C7.04 as having phase-specific expression patterns during the cell cycle, clustering with genes involved in M phase regulation .
The protein's localization to both nuclear and cytoplasmic compartments suggests it may shuttle between these locations, possibly in response to specific cellular signals or cell cycle stages .
Comprehensive validation of SPAC3C7.04 antibodies should employ multiple complementary approaches:
Western Blotting Validation:
Use wild-type S. pombe extracts alongside SPAC3C7.04 deletion strains
Expected molecular weight is approximately 87 kDa (calculated from 783 amino acids)
Test antibody specificity across varying protein concentrations (5-50 μg of total protein)
Include positive controls with tagged versions of SPAC3C7.04 (e.g., GFP-SPAC3C7.04)
Immunocytochemistry Validation:
Compare staining patterns between wild-type and knockout strains
Co-localization with nuclear markers is expected given its known nuclear localization
Assess puncta co-localization with markers for transcription factories
Calculate ratio between co-localizing and non-co-localizing signals as demonstrated in similar validation protocols
Immunoprecipitation:
Validate ability to pull down SPAC3C7.04 and associated proteins
Confirm identity of precipitated protein via mass spectrometry
Use chromatin immunoprecipitation to confirm DNA-binding sites
Cross-Reactivity Analysis:
The most rigorous validation integrates all these approaches, with particular emphasis on genetic controls (deletion strains) to definitively establish specificity .
For effective ChIP using SPAC3C7.04 antibodies, we recommend the following optimized protocol:
Fixation and Crosslinking:
Grow S. pombe cells to mid-log phase (OD600 = 0.5-0.8)
Crosslink with 1% formaldehyde for 15 minutes at room temperature
Quench with 125 mM glycine for 5 minutes
Wash cells 3× with cold PBS
Chromatin Preparation:
Lyse cells using glass beads in lysis buffer (50 mM HEPES-KOH pH 7.5, 140 mM NaCl, 1 mM EDTA, 1% Triton X-100, 0.1% sodium deoxycholate, protease inhibitors)
Sonicate to generate DNA fragments of 200-500 bp
Clear lysate by centrifugation at 14,000×g for 10 minutes
Immunoprecipitation:
Pre-clear chromatin with Protein A/G beads for 1 hour at 4°C
Incubate 100 μg of chromatin with 5-10 μg SPAC3C7.04 antibody overnight at 4°C
Add Protein A/G beads and incubate for 2 hours at 4°C
Wash progressively with:
Low salt wash buffer (0.1% SDS, 1% Triton X-100, 2 mM EDTA, 20 mM Tris-HCl pH 8.0, 150 mM NaCl)
High salt wash buffer (same as low salt but with 500 mM NaCl)
LiCl wash buffer (0.25 M LiCl, 1% NP-40, 1% sodium deoxycholate, 1 mM EDTA, 10 mM Tris-HCl pH 8.0)
TE buffer (10 mM Tris-HCl pH 8.0, 1 mM EDTA)
Elution and Reversal of Crosslinks:
Elute with elution buffer (1% SDS, 0.1 M NaHCO3)
Reverse crosslinks at 65°C overnight
Treat with RNase A and Proteinase K
Purify DNA using phenol-chloroform extraction or commercial kits
This protocol has been adapted from chromatin immunoprecipitation studies in S. pombe that successfully isolated chromatin-bound proteins . For SPAC3C7.04 specifically, focus on enrichment of regions containing fungal Zn(2)-Cys(6) binding motifs.
To investigate SPAC3C7.04's role in cell cycle regulation using antibodies:
Experimental Design Strategy:
Cell Cycle Synchronization and ChIP-seq Analysis:
Synchronize S. pombe cells using nitrogen starvation and release
Collect samples at 20-minute intervals throughout the cell cycle
Perform ChIP-seq with SPAC3C7.04 antibodies at each timepoint
Identify dynamic binding patterns and correlate with cell cycle phases
Compare to known periodic transcription factors like Fkh2, which shows late G2 activity
Co-Immunoprecipitation at Different Cell Cycle Stages:
Synchronize cells and collect at G1, S, G2, and M phases
Immunoprecipitate SPAC3C7.04 at each phase
Identify phase-specific interaction partners by mass spectrometry
Create interaction networks showing temporal dynamics
Phosphorylation State Analysis:
Use phospho-specific antibodies or general SPAC3C7.04 antibodies followed by phospho-enrichment
Map phosphorylation sites that change during cell cycle progression
Connect to known CDK or cell cycle kinase consensus motifs
The genetic interaction data shows potential connections to cell cycle regulation , and global gene regulatory network analysis places SPAC3C7.04 in context with known cell cycle regulators like SPBC19G7.04 and Fkh2 . Utilizing antibodies to map its dynamic binding patterns, interaction partners, and post-translational modifications will reveal its regulatory mechanisms.
To elucidate SPAC3C7.04's position in transcriptional regulatory networks:
Multi-dimensional Experimental Approach:
Sequential ChIP (Re-ChIP) Analysis:
Primary ChIP with SPAC3C7.04 antibody
Secondary ChIP with antibodies against potential co-regulators:
Identify genomic loci where multiple factors co-bind
Proximity-Dependent Biotin Identification (BioID):
Create SPAC3C7.04-BirA fusion proteins
Identify proteins in close proximity to SPAC3C7.04 in living cells
Compare the proximity interactome with known transcription factors and co-regulators
Integrative Network Analysis:
Combine ChIP-seq data with RNA-seq from SPAC3C7.04 deletion/overexpression strains
Construct directed regulatory networks showing target genes
Perform motif analysis to identify binding sequence preferences
Correlate with datasets from existing transcription factor studies
Synthetic Genetic Array Analysis:
Network analysis from previous studies has already placed SPAC3C7.04 in context with several cell cycle-regulated transcription factors . The P-value of 2.84E-15 for its fungal Zn(2)-Cys(6) binuclear cluster domain indicates a highly significant role in transcriptional regulation that warrants deep investigation of its network connections.
When facing difficulties detecting SPAC3C7.04 in immunoprecipitation experiments:
Methodological Solutions:
Optimize Extraction Conditions:
Test different lysis buffers with varying salt concentrations (150-500 mM NaCl)
Include specialized detergents for nuclear proteins (0.1-0.5% NP-40 or 0.1% SDS)
Incorporate sonication steps to disrupt nuclear membranes
Add specialized nuclear extraction reagents like benzonase nuclease
Cross-linking Optimization:
Test dual cross-linking with DSP (dithiobis[succinimidyl propionate]) before formaldehyde
Optimize formaldehyde concentration (0.5-2%) and cross-linking times (10-30 minutes)
Use protein-protein cross-linkers for transient interactions
Antibody Enhancement Strategies:
Pre-clear lysates thoroughly to reduce non-specific binding
Utilize antibody concentrations between 2-10 μg per 1 mg of protein lysate
Consider using a cocktail of antibodies targeting different epitopes
Employ epitope-tagged SPAC3C7.04 (HA, FLAG, etc.) as a parallel approach
Detection Enhancement:
Use highly sensitive western blot detection systems (ECL Prime or Femto)
Consider mass spectrometry-based detection for low abundance proteins
Implement signal amplification methods like biotin-streptavidin systems
Since SPAC3C7.04 is involved in transcriptional regulation and has both nuclear and cytoplasmic localization , extraction conditions are particularly critical. The dual localization may also indicate different functional pools with varying extraction requirements.
To reduce background signals in immunofluorescence microscopy:
Optimization Protocol:
Fixation and Permeabilization Refinement:
Compare different fixatives: 4% paraformaldehyde, methanol, or methanol-acetone
Test permeabilization agents: 0.1-0.5% Triton X-100, 0.05-0.2% Saponin, or 0.01-0.1% SDS
Optimize fixation times (10-30 minutes) and permeabilization times (5-15 minutes)
Blocking Protocol Enhancement:
Extend blocking time to 1-2 hours at room temperature
Test different blocking agents:
5% normal serum from the species of secondary antibody origin
3-5% BSA with 0.1-0.3% Tween-20
Commercial blocking reagents with protein-free formulations
Include 0.05-0.2% Tween-20 in all antibody dilution and wash buffers
Antibody Dilution Optimization:
Test serial dilutions from 1:100 to 1:2000
Extend primary antibody incubation to overnight at 4°C
Perform extensive washing (5× 5 minutes) after antibody incubations
Pre-absorb antibodies with cell extracts from SPAC3C7.04 deletion strains
Controls and Signal Verification:
Include SPAC3C7.04 deletion strains as negative controls
Use peptide competition assays to confirm specificity
Compare staining patterns with GFP-tagged SPAC3C7.04 in live cells
Quantify signal-to-noise ratios using image analysis software
Mounting Media Optimization:
Test anti-fade agents with different refractive indices
Include DAPI or other nuclear counterstains to verify nuclear localization
Consider using clearing agents for better signal penetration
For transcription factors like SPAC3C7.04 with dual localization patterns , distinguishing specific signal from background is particularly challenging. Quantitative co-localization analysis with nuclear markers can help verify true signals from artifacts.
When interpreting ChIP-seq data for SPAC3C7.04 in cell cycle contexts:
Analytical Framework:
Phase-Specific Binding Pattern Analysis:
Map SPAC3C7.04 binding sites to gene promoters and regulatory regions
Group target genes by cell cycle phase expression patterns
Compare binding profiles across synchronized timepoints
Create heat maps showing temporal binding dynamics
Look specifically for co-regulation with the Fkh2 transcription factor, which has been shown to have coordinated late G2 phase activity
Motif Analysis and Integration:
Identify enriched DNA motifs in binding regions using MEME or similar tools
Compare identified motifs with known binuclear Zn cluster consensus sequences
Look for composite motifs suggesting co-factor binding
Integrate with published S. pombe regulatory motif databases
Target Gene Function Analysis:
Comparative Analysis with Known Cell Cycle Regulators:
Overlay binding data with other cell cycle transcription factors
Identify regions of co-binding or mutually exclusive binding
Calculate statistical significance of binding site overlaps
Create integrated regulatory maps showing temporal coordination
Integration with Expression Data:
Correlate binding strength with target gene expression levels
Determine if SPAC3C7.04 functions primarily as an activator or repressor
Identify any discordant binding-expression relationships
Previous studies have placed SPAC3C7.04 in the context of cell cycle regulation , making it essential to interpret ChIP-seq data with specific attention to phase-specific binding patterns and coordination with known cell cycle regulators.
To comprehensively define the SPAC3C7.04 regulon:
Integrated Bioinformatic Strategy:
Multi-omic Data Integration:
Combine ChIP-seq data with RNA-seq from knockout/overexpression experiments
Integrate proteomics data to confirm translation of target gene mRNAs
Include metabolomic data for downstream functional effects
Use machine learning to weight different data types in predicting direct vs. indirect targets
Network Inference Algorithms:
Apply ARACNE, GENIE3, or similar algorithms to infer regulatory relationships
Build Bayesian networks incorporating prior knowledge from existing S. pombe datasets
Use time-lagged correlation analysis for cell cycle synchronized datasets
Employ module detection algorithms to identify co-regulated gene clusters
Comparative Genomics Approach:
Compare SPAC3C7.04 binding sites across different fission yeast species
Identify evolutionarily conserved targets as core regulon components
Use orthology mapping to relate targets to known regulons in other fungi
Apply phylogenetic footprinting to identify conserved regulatory motifs
Synthetic Genetic Analysis Integration:
Data Visualization and Analysis:
Create interactive network visualizations with Cytoscape
Implement hierarchical clustering of targets based on expression patterns
Develop phase-specific regulon maps for cell cycle-regulated targets
Calculate statistical significance of regulon enrichment for specific functions
The comprehensive systems-level analysis previously applied to S. pombe cell cycle regulation provides an excellent methodological template. Similar approaches can be used to fully characterize the SPAC3C7.04 regulon, with particular attention to its fungal Zn(2)-Cys(6) binuclear cluster domain binding preferences.
To adapt SPAC3C7.04 antibodies for proximity labeling studies:
Methodological Implementations:
Antibody-Directed BioID Approaches:
Conjugate SPAC3C7.04 antibodies to modified BirA* enzyme
Optimize biotin concentration (50-500 μM) and labeling times (15-360 minutes)
Extract biotinylated proteins using streptavidin pulldown
Identify proximal proteins via mass spectrometry
Compare interaction networks across cell cycle stages
APEX2-Based Proximity Labeling:
Conjugate antibodies to APEX2 peroxidase
Optimize H₂O₂ concentration (0.5-5 mM) and labeling time (30 seconds-5 minutes)
Identify rapidly labeled proximal proteins
Create spatiotemporal maps of SPAC3C7.04 interactions
Split-BioID or Split-APEX Approaches:
Generate constructs with SPAC3C7.04 fused to one half of split BioID
Create libraries of potential interactors fused to complementary half
Identify specific interactions through reconstituted enzymatic activity
Validate interactions using co-immunoprecipitation with SPAC3C7.04 antibodies
In situ Proximity Ligation Assay (PLA):
Use SPAC3C7.04 antibodies with antibodies against suspected interaction partners
Visualize and quantify interactions as fluorescent puncta
Map interaction dynamics throughout the cell cycle
Compare interaction patterns in different cellular compartments
Calibration and Controls:
Use GFP-tagged SPAC3C7.04 as positive control
Include SPAC3C7.04 deletion strains as negative controls
Perform parallel experiments with non-specific IgG antibodies
Calculate enrichment ratios relative to controls
Given SPAC3C7.04's role in transcriptional networks and its dual localization , proximity labeling can reveal both nuclear transcriptional complexes and potential cytoplasmic regulatory interactions or transport factors.
To investigate post-translational regulation of SPAC3C7.04:
Comprehensive PTM Analysis Strategy:
Phosphorylation Analysis:
Immunoprecipitate SPAC3C7.04 using validated antibodies
Perform phospho-specific western blots or Phos-tag SDS-PAGE
Analyze phosphorylation sites using mass spectrometry
Compare phosphorylation patterns across cell cycle stages
Focus on S2, S6, S685, S697, S699, and T701 sites previously identified in related proteins
Ubiquitination and SUMOylation Analysis:
Acetylation and Methylation:
Immunoprecipitate with SPAC3C7.04 antibodies
Probe western blots with pan-acetyl-lysine or methyl-lysine antibodies
Perform mass spectrometry to map specific modification sites
Compare with known acetylation patterns on zinc finger domains
Functional Impact Assessment:
Generate phosphomimetic and phospho-deficient mutants
Perform ChIP-seq to compare binding profiles of modified vs. unmodified forms
Correlate modifications with transcriptional output of target genes
Investigate temporal dynamics of modifications during cell cycle progression
Enzyme Identification:
Use proximity labeling to identify candidate modifying enzymes
Perform genetic interaction screens with known kinases, phosphatases, and other PTM enzymes
Validate with targeted enzyme inhibition or deletion
The identification of phosphorylation sites on similar regulatory proteins suggests that SPAC3C7.04 likely undergoes similar regulation. Given its role in cell cycle regulation , post-translational modifications probably control its activity in a phase-specific manner.
When comparing monoclonal and polyclonal SPAC3C7.04 antibodies:
Comparative Analysis Table:
| Parameter | Monoclonal SPAC3C7.04 Antibodies | Polyclonal SPAC3C7.04 Antibodies | Recommendation |
|---|---|---|---|
| Specificity | Higher specificity to single epitope | Recognizes multiple epitopes | Monoclonal for precise epitope targeting; polyclonal for robust detection |
| ChIP-seq Performance | Lower yield but higher specificity | Higher yield with potential for non-specific binding | Monoclonal preferred for mapping precise binding sites |
| Western Blot | Cleaner background but may miss conformational changes | More robust detection but higher background | Polyclonal for initial detection; monoclonal for confirmation |
| Immunofluorescence | Less sensitive but more specific localization | More sensitive but potential cross-reactivity | Monoclonal for co-localization studies; polyclonal for weak signals |
| Immunoprecipitation | May have lower recovery but higher purity | Better capture efficiency but lower purity | Polyclonal for IP; monoclonal for detection |
| Post-translational Modification Detection | Superior if epitope-specific to modification | May be blocked by modifications if epitopes are affected | Epitope-specific monoclonal targeting regions of interest |
| Batch-to-batch Variability | Very low variability | Higher variability requiring validation of each lot | Monoclonal for long-term reproducible studies |
| Production Complexity | Higher initial investment but consistent supply | Easier initial production but requires revalidation | Dependent on project timeline and budget |
Application-Specific Recommendations:
For transcription factors like SPAC3C7.04 with specific DNA-binding domains , monoclonal antibodies targeting the DNA-binding region are ideal for ChIP applications, while polyclonal antibodies may be better for detecting the protein in multiple experimental contexts. The recombinant monoclonal approach, similar to that used for other transcription factors , offers advantages in specificity and reproducibility for long-term studies.
When deciding between antibody-based detection and epitope tagging for SPAC3C7.04 research:
Decision Framework:
Experimental Objectives Assessment:
| Research Goal | Antibody Approach | Epitope Tagging Approach |
|---|---|---|
| Endogenous expression analysis | Preferred - maintains native regulation | Limited - tag may affect expression |
| Protein-protein interactions | Variable success depending on epitope accessibility | Highly effective with established tag purification |
| Chromatin binding (ChIP) | May interfere with DNA binding if targeting Zn cluster domain | May alter DNA binding if tag is near DNA-binding domain |
| Subcellular localization | Requires fixation, potential artifacts | Live cell imaging possible with fluorescent tags |
| Post-translational modifications | Can detect natural modifications | Tag may interfere with some modifications |
| Conditional depletion | Not applicable | Enables degron tagging for targeted degradation |
Technical Considerations:
Antibody-based approach advantages:
Detects endogenous protein without genetic manipulation
Preserves all natural splice variants and modifications
No concerns about tag-induced artifacts
Epitope tagging advantages:
Consistent detection regardless of conformation
Standardized purification protocols with high reproducibility
Enables live-cell imaging with fluorescent tags
Experimental Validation Strategy:
Biological Considerations:
Combined Strategy Recommendation:
Use both approaches in parallel for cross-validation
Employ antibodies for initial characterization of endogenous function
Use tagging for specific applications requiring high sensitivity or live-cell analysis
For SPAC3C7.04, with its critical role in transcriptional networks and potentially dynamic cell cycle regulation , the combination of both approaches provides the most comprehensive and reliable results.
SPAC3C7.04 antibodies can illuminate transcription factor involvement in non-coding RNA regulation through:
Innovative Research Approaches:
Comprehensive Genomic Binding Analysis:
Perform ChIP-seq to map SPAC3C7.04 binding across the entire genome, including non-coding regions
Analyze binding to promoters of known non-coding RNA genes
Identify enrichment at enhancers or silencers that regulate ncRNA transcription
Compare binding profiles in wild-type versus stress conditions
Non-coding RNA-Protein Interaction Studies:
Use RNA immunoprecipitation (RIP) with SPAC3C7.04 antibodies
Identify direct RNA-protein interactions
Implement CLIP-seq (cross-linking immunoprecipitation) to map RNA binding sites at nucleotide resolution
Compare RNA interactions between nuclear and cytoplasmic fractions
Functional Impact Assessment:
Correlate SPAC3C7.04 binding with expression of proximal non-coding RNAs
Analyze SPAC3C7.04 knockout effects on ncRNA transcriptome using RNA-seq
Investigate whether SPAC3C7.04 regulates antisense transcripts of its target genes
Examine effects on cell cycle-regulated long non-coding RNAs
Mechanistic Studies:
Investigate co-localization with RNA polymerase II and III at ncRNA loci
Identify SPAC3C7.04 interactions with chromatin remodeling complexes that regulate ncRNA expression
Examine involvement in phase separation at transcriptional condensates
Test for pioneer factor activity in opening chromatin at ncRNA loci
The dual nuclear/cytoplasmic localization of SPAC3C7.04 suggests potential roles in both transcriptional and post-transcriptional regulation of RNAs. Given its function as a transcription factor with cell cycle connections , it may specifically regulate ncRNAs involved in cell cycle progression.
To investigate SPAC3C7.04's potential involvement in phase-separated transcriptional condensates:
Multidisciplinary Experimental Strategy:
Microscopy-Based Condensate Analysis:
Perform immunofluorescence with SPAC3C7.04 antibodies and known condensate markers
Quantify co-localization with transcriptional condensate components
Analyze condensate dynamics during cell cycle progression
Use super-resolution microscopy to characterize condensate structure
Implement optogenetic tools to trigger condensate formation/dissolution
Biochemical Phase Separation Assays:
Express and purify SPAC3C7.04 protein domains
Test for in vitro phase separation properties
Examine effects of DNA/RNA on phase separation behavior
Investigate impact of post-translational modifications on condensate formation
Analyze domain requirements for phase separation
Molecular Dynamics Studies:
Identify intrinsically disordered regions (IDRs) in SPAC3C7.04 sequence
Examine prion-like domains or low complexity sequences
Predict phase separation propensity using algorithms like PLAAC or catGRANULE
Model interactions with known condensate scaffolds
Functional Impact Assessment:
Create domain mutants that disrupt phase separation properties
Perform ChIP-seq to compare genomic binding of wild-type vs. mutant proteins
Analyze transcriptional output of target genes
Examine effects on target gene clustering in nuclear space
Investigate impact on transcriptional bursting
Dynamics and Regulation: