RAD23B Antibody

What is RAD23B and why is it important in cellular research?

RAD23B (RAD23 homolog B) is a multifunctional protein belonging to the RAD23 family that plays crucial roles in nucleotide excision repair (NER) and the ubiquitin-proteasome system. It functions as both a DNA repair protein and a shuttling factor for ubiquitinated proteins destined for proteasomal degradation.

Specifically, RAD23B:

• Functions as a component of the XPC complex involved in global genome nucleotide excision repair (GG-NER)

• Contains an N-terminal ubiquitin-like domain that interacts with the 26S proteasome

• Possesses ubiquitin-associated domains (UBA1 and UBA2) that bind to polyubiquitinated proteins

• Serves as an essential link between ubiquitinated proteins and proteasomal degradation machinery

This dual functionality makes RAD23B a critical protein for studying both DNA repair mechanisms and protein quality control pathways.

What applications are RAD23B antibodies suitable for?

RAD23B antibodies have been validated for multiple laboratory applications, with varying dilution requirements:

These applications allow researchers to detect, localize, and quantify RAD23B in various experimental systems, from cell cultures to tissue specimens .

What is the expected molecular weight of RAD23B in Western blot analyses?

Although the calculated molecular weight of RAD23B based on its amino acid sequence is approximately 43 kDa, the protein typically migrates at 53-58 kDa on SDS-PAGE gels . This discrepancy between calculated and observed molecular weights is consistent across multiple antibodies and research publications.

The higher apparent molecular weight may be attributed to:

• Post-translational modifications

• The specific structural conformation of the protein

• The presence of charged residues affecting migration patterns

Researchers should expect to see bands at approximately 58 kDa when performing Western blot analysis of RAD23B .

How should I optimize RAD23B antibody dilutions for my specific experimental system?

Optimization of RAD23B antibody concentrations is critical for obtaining specific signals while minimizing background. A systematic approach includes:

• Start with manufacturer's recommended dilutions: For example, 1:5000-1:50000 for WB, 1:1000-1:4000 for IHC, and 1:400-1:1600 for IF/ICC

• Perform a dilution series: Test 3-4 different dilutions spanning the recommended range

• Include appropriate controls:

  • Positive controls: Cell lines with confirmed RAD23B expression (HeLa, HEK-293, LNCaP)

  • Tissue controls: Brain tissue from human, mouse, or rat specimens has been validated

  • Negative controls: Secondary antibody-only controls to assess non-specific binding

• Adjust based on signal-to-noise ratio: Higher dilutions may be needed for samples with high RAD23B expression levels

Note that optimal dilutions may be sample-dependent; for example, different tissue types may require different antibody concentrations for optimal results .

What antigen retrieval methods are recommended for RAD23B immunohistochemistry?

Proper antigen retrieval is essential for exposing RAD23B epitopes in fixed tissues. Based on validated protocols:

• Primary recommendation: TE buffer pH 9.0

  • Higher pH improves retrieval of certain epitopes in RAD23B

• Alternative method: Citrate buffer pH 6.0

  • May be preferred for specific tissue types or fixation methods

The optimal retrieval method may depend on:

• Fixation time and conditions

• Tissue type

• Specific epitope targeted by the antibody

For FFPE (formalin-fixed paraffin-embedded) tissue sections, heat-induced epitope retrieval (HIER) is generally recommended . Researchers should validate antigen retrieval methods for their specific experimental conditions.

How should RAD23B antibodies be stored to maintain optimal activity?

Proper storage conditions are critical for maintaining antibody performance over time:

• Temperature: Store at -20°C for long-term storage

  • Avoid repeated freeze-thaw cycles

  • The antibodies are generally stable for one year after shipment when stored correctly

• Buffer composition: Most RAD23B antibodies are supplied in:

  • PBS with 0.02% sodium azide

  • 50% glycerol at pH 7.3

  • Some preparations may contain 0.1% BSA as a stabilizer

• Aliquoting: For 20μL size preparations, aliquoting is unnecessary for -20°C storage

  • Larger volumes should be aliquoted to avoid repeated freeze-thaw cycles

• Working dilutions: Store diluted antibody solutions at 4°C for short-term use (1-2 weeks)

Following these storage recommendations helps ensure consistent antibody performance across experiments .

How can RAD23B antibodies be used to study the interaction between nucleotide excision repair and the ubiquitin-proteasome system?

RAD23B uniquely bridges DNA repair and protein degradation pathways, making it an excellent target for studying their interconnection:

• Co-immunoprecipitation (Co-IP) experiments:

  • RAD23B antibodies can pull down associated proteins from both pathways

  • Useful for identifying novel interaction partners or characterizing known interactions

  • Can detect complexes with XPC (repair pathway) and ubiquitinated proteins (degradation pathway)

• Chromatin immunoprecipitation (ChIP):

  • RAD23B antibodies can help detect recruitment of repair complexes to DNA damage sites

  • Can be combined with sequencing (ChIP-seq) to map genome-wide binding locations

• Sequential immunoprecipitation:

  • First IP: Ubiquitinated proteins

  • Second IP: RAD23B

  • Identifies specifically which ubiquitinated proteins associate with RAD23B

• Proximity ligation assay (PLA):

  • Visualizes interactions between RAD23B and proteins from either pathway

  • Provides spatial information about where these interactions occur within cells

These approaches can reveal how RAD23B's dual functionality coordinates cellular responses to DNA damage and protein homeostasis .

What considerations are important when using RAD23B antibodies to study its dynamic interactions with the XPC complex?

When investigating RAD23B's role in the XPC complex and DNA damage recognition:

• Single-molecule visualization approaches:

  • High-throughput single-molecule imaging has revealed three distinct modes of RAD23B-XPC motion along DNA: diffusive, immobile, and constrained

  • These experiments require highly specific antibodies or tagged constructs

• Structural considerations:

  • Recent cryo-EM studies of TFIIH/Rad4–Rad23–Rad33 (yeast homolog of XPC-RAD23B-CETN2) have revealed how this complex assembles on damaged DNA

  • Antibodies targeting specific domains of RAD23B can help dissect structural requirements

• Experimental timing:

  • RAD23B-XPC interactions with DNA damage occur rapidly

  • Time-course experiments with synchronized damage induction provide better resolution

  • Fixation timing is critical for capturing transient interactions

• Protocol adaptations:

  • For immunofluorescence studies: Use shorter fixation times (5-10 minutes)

  • For western blotting: Consider non-denaturing conditions to preserve protein interactions

  • For chromatin fractionation: Optimize salt concentrations to distinguish loosely vs. tightly bound complexes

These approaches help capture the dynamic nature of RAD23B's involvement in DNA damage recognition and verification .

How can RAD23B antibodies help differentiate between its DNA repair and proteasomal functions?

Distinguishing between RAD23B's dual roles requires targeted experimental approaches:

• Domain-specific antibodies:

  • N-terminal (UbL domain) antibodies: Focus on proteasome interactions

  • XPC-binding domain antibodies: Target DNA repair function

  • C-terminal (UBA domains) antibodies: Examine ubiquitin binding

• Subcellular fractionation combined with immunoblotting:

  • Nuclear fraction: Enriched for DNA repair-associated RAD23B

  • Cytoplasmic/ER fraction: Contains more proteasome/ERAD-associated RAD23B

  • Proteasome-bound fraction: Can be isolated via proteasome pulldown

• Functional perturbation experiments:

  • DNA damage induction (UV, cisplatin): Shifts RAD23B toward repair function

  • Proteasome inhibition (MG132, bortezomib): Alters RAD23B's association with ubiquitinated proteins

• Co-localization studies:

  • Dual immunofluorescence with RAD23B antibodies plus:

    • DNA damage markers (γH2AX, XPC): Indicates repair function

    • Proteasome markers (PSMD4/S5a): Shows degradation pathway involvement

    • Ubiquitinated protein accumulation sites: Reveals shuttling function

These approaches help determine which cellular function of RAD23B predominates under specific experimental conditions .

How do I resolve discrepancies between expected and observed molecular weights of RAD23B in Western blots?

When investigating apparent molecular weight discrepancies:

• Understand normal migration patterns:

  • Calculated weight: 43 kDa (409 amino acids)

  • Typically observed weight: 53-58 kDa

  • This difference is consistently reported across antibodies and is not an experimental artifact

• Potential causes for higher molecular weight:

  • Post-translational modifications (phosphorylation, ubiquitination)

  • Presence of isoforms (RAD23B has two known isoforms: 43 kDa and 35 kDa)

  • Incomplete denaturation due to protein structure

• Verification approaches:

  • Use multiple antibodies targeting different epitopes

  • Include recombinant protein standards

  • Test cell lines with confirmed RAD23B expression (HeLa, HEK-293)

  • Consider knockdown/knockout samples as negative controls

• Optimization strategies:

  • Adjust denaturation conditions (increase boiling time/temperature)

  • Try reducing agent concentration variations

  • Test different gel percentages for better resolution

  • Consider gradient gels for better separation

The consistent observation of higher molecular weight bands across multiple antibodies suggests this is the true migration pattern of RAD23B rather than an artifact .

What are the common causes of non-specific binding with RAD23B antibodies and how can they be addressed?

Non-specific binding can complicate data interpretation. Here are common issues and solutions:

• Cross-reactivity with related proteins:

  • RAD23A shares significant homology with RAD23B

  • Solution: Use antibodies specifically validated against both proteins

  • Some applications may benefit from antibodies that recognize both (pan-RAD23)

• Background in immunohistochemistry/immunofluorescence:

  • Blocking optimization: Use 3-5% BSA or 5-10% normal serum from the species of secondary antibody

  • Increase antibody dilution (particularly for high-expression samples)

  • Perform antigen retrieval optimization

  • Include a peptide competition assay to confirm specificity

• Multiple bands in Western blot:

  • Expected: Primary band at 58 kDa

  • Common non-specific bands: 43-45 kDa (may represent degradation products)

  • Solution: Optimize protein extraction conditions to minimize degradation

  • Test different lysis buffers with varied protease inhibitor combinations

• Tissue-specific considerations:

  • Brain tissue: Higher background common; increase dilution to 1:30000-1:50000 for WB

  • Cell lines: HeLa and HEK-293 are good positive controls with clean signal

Thorough validation with appropriate controls helps distinguish specific from non-specific signals .

How do I interpret inconsistent RAD23B antibody immunoreactivity across different experimental conditions?

Variability in RAD23B detection may have biological or technical causes:

• Cell cycle-dependent expression and localization:

  • RAD23B exhibits cell cycle-dependent intracellular distribution

  • Cell synchronization may be necessary for consistent results

  • Compare results from populations at similar cell cycle stages

• Stress-dependent dynamics:

  • RAD23B interactions with partners like Atx3 and VCP are modulated by proteotoxic stress

  • DNA damage induces changes in RAD23B-XPC complex formation

  • Document and control stress conditions during experimental procedures

• Sample preparation variables:

  • Fixation duration affects epitope accessibility (particularly for IHC/IF)

  • Lysis conditions influence protein extraction efficiency

  • Keep preparation protocols consistent across experiments

  • Document fixation times, buffer compositions, and incubation durations

• Technical optimization:

  • Test multiple antibody lots if available

  • Include internal loading controls

  • Perform parallel processing of all samples to minimize batch effects

  • Consider multiplex approaches (e.g., fluorescent WB with multiple detection channels)

Systematic documentation of experimental conditions helps identify sources of variability and distinguish technical from biological variations .

How can RAD23B antibodies be utilized in studying the relationship between DNA repair deficiencies and cancer development?

RAD23B antibodies offer valuable tools for investigating DNA repair in cancer contexts:

• Biomarker evaluation in clinical specimens:

  • IHC analysis of tumor microarrays to correlate RAD23B expression with:

    • Cancer subtypes

    • Treatment response

    • Patient outcomes

  • RAD23B has been identified as a potential cancer biomarker in genome-wide screens

• Functional analysis in cancer models:

  • RAD23B antibodies can assess protein levels/localization in:

    • Patient-derived xenografts

    • Cancer cell lines with varying repair capacities

    • Isogenic cell lines with engineered repair deficiencies

• Therapy response studies:

  • RAD23B influences sensitivity to HDAC inhibitors

  • Monitor RAD23B complex formation before/after treatment with:

    • DNA damaging agents (platinum drugs, radiation)

    • Proteasome inhibitors

    • Epigenetic modulators

• High-throughput screening applications:

  • Automated microscopy with RAD23B antibodies can identify compounds that:

    • Alter RAD23B localization

    • Disrupt RAD23B-XPC complex formation

    • Modulate recruitment to damage sites

These approaches help elucidate RAD23B's contribution to genomic stability and its potential as a therapeutic target .

What approaches can be used to study RAD23B's dynamic motions along DNA using antibody-based techniques?

Building on recent single-molecule studies, several antibody-based approaches can reveal RAD23B-DNA interactions:

• Antibody-based single-molecule tracking:

  • Direct labeling of RAD23B antibodies with quantum dots or fluorophores

  • Enables visualization of:

    • Diffusive motion (hopping mechanism)

    • Immobile binding at damage sites

    • Constrained movement patterns

• DNA curtain assays with antibody detection:

  • Tethered DNA molecules arranged in parallel arrays

  • RAD23B behavior observed via:

    • Fluorescent antibodies

    • Antibody-conjugated quantum dots

  • Reveals dynamics at single-molecule resolution

• Combined ChIP-exo/ChIP-nexus with RAD23B antibodies:

  • High-resolution mapping of RAD23B binding sites

  • Nucleotide-level precision for damage recognition events

  • Identifies sequence preferences for binding/scanning

• Proximity ligation microscopy with RAD23B antibodies:

  • Real-time visualization of protein-DNA interactions

  • Can distinguish between searching, recognition, and stable binding phases

These techniques provide insight into how RAD23B searches for DNA damage among billions of base pairs and can reveal the molecular mechanisms of damage recognition .

How can RAD23B antibodies be employed to investigate the role of RAD23B in plant cell biology and agriculture?

RAD23B antibodies have applications in plant research, where RAD23 proteins serve important functions:

• Evolutionary conservation studies:

  • Cross-species reactivity of RAD23 antibodies

  • Compare RAD23 function across evolutionary diverse plants:

    • Arabidopsis thaliana (model system)

    • Crop species

    • Stress-resistant plant varieties

• Plant stress response research:

  • RAD23 proteins are essential for plant cell cycle, morphology, and fertility

  • Antibody-based assays can detect:

    • Changes in RAD23 levels during abiotic stress

    • Alterations in subcellular localization

    • Protein complex formation under stress conditions

• Agricultural applications:

  • UV resistance screening:

    • RAD23 proteins play roles in UV tolerance in roots, specifically in dark conditions

    • Antibody-based screening for RAD23 expression/function

  • Crop improvement:

    • Identify cultivars with enhanced RAD23 expression/function

    • Study correlation between RAD23 levels and stress tolerance

• Technical considerations for plant samples:

  • Use antibodies validated for plant species (e.g., Arabidopsis-specific antibodies)

  • Optimize protein extraction protocols for plant tissues

  • Consider plant-specific fixation methods for microscopy