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PAX3 · Western blot design guide
Design a Western Blot for PAX3
Real validated PAX3 Western blot protocols, expected-band and isoform facts, troubleshooting for weak or shifted signal, and recommended anti-PAX3 WB antibodies. Everything you need to plan the experiment before you commit precious samples.
Last reviewed: May 2026 · Scientific review: Boster Bio technical team
PAX3 Western Blot Experimental Design Guide
Expected bands, validated protocols, controls and antibodies — the at-a-glance facts below, then the full design guide.
Must know before running
| Expected band | ~53 kDa | |
| Observed band | ~53 kDa | |
| Gel | 10–12% | |
| Negative control | siRNA / KO lysate |
Important caveats
Reasons your observed band may differ from the expected size.
| PTM | Phosphorylated | |
| Caveat | Alternative splicing isoforms | |
| Regulation | Kras signaling dn | |
| Isoform | 8 isoform(s) |
Section 1
Real Curated PAX3 Western Blot Protocols
Literature-validated Western blot parameters for PAX3 — gel percentage, transfer, blocking, antibody incubation and detection, extracted from published methods.
| Sample / lysate | human SH-SY5Y , Lane 2: human K562 , Lane 3: human SW620 , Lane 4: rat brain , Lane 5: mouse NIH/3T3 . After Electrophoresis, proteins were transferred to a Nitrocellulose membrane at 150mA for 50-90 minutes. Blocked the membrane with 5% Non-fat Milk/ TBS for 1.5 hour at RT. The membrane was incubated with rabbit anti-PAX3 antigen affinity purified polyclonal antibody (Catalog # A00285-1) at 0.5 μg/mL overnight at 4°C, then washed with TBS-0.1%Tween 3 times with 5 minutes each and probed with a goat anti-rabbit IgG-HRP secondary antibody at a dilution of 1:5000 for 1.5 hour at RT. The signal is developed using an Enhanced Chemiluminescent detection (ECL) kit (Catalog # EK1002) with Tanon 5200 system. A specific band was detected for PAX3 at approximately 53KD. The expected band size for PAX3 is at 53KD |
| Gel % | 10–12% |
| Load | 30ug |
| Transfer | nitrocellulose membrane, 150 mA, 50–90 min |
| Membrane | nitrocellulose |
| Blocking | 5% non-fat milk / TBS, 1.5 h RT |
| Primary antibody | 0.5 µg/mL |
| Primary incubation | overnight at 4 °C |
| Secondary antibody | goat anti-rabbit IgG-HRP, 1:5000 |
| Wash | TBS-0.1% Tween, 3 × 5 min |
| Detection | ECL |
| Exposure / imaging | Tanon 5200 |
| Observed band | 53 kDa |
Section 2
What Is the Expected PAX3 Western Blot Band Size?
PAX3 has a 53 kDa predicted mass and runs at the same observed 53 kDa on Western blots because it lacks glycosylation, cleavage, and disulfide bonds that would otherwise shift its size.
| Single sharp band at about 53 kDa | matches the unmodified 479-residue PAX3 backbone since the protein carries no glycosylation, disulfide bonds, or cleavage sites that would shift its mass |
| Several distinct bands across different cell lines or tissues | reflects the 8 annotated PAX3 splice isoforms, which differ in exon content and may be captured differently depending on antibody epitope |
| Band present mainly in nuclear-enriched fractions, faint in whole-cell lysate | PAX3 is a nuclear transcription factor, so standard whole-cell lysis may under-represent it relative to a nuclear extraction protocol |
| No band at roughly twice the monomer mass under standard reducing SDS-PAGE | PAX3 forms homodimers and PAX7 heterodimers through DNA binding rather than inter-chain disulfide bonds, so SDS and reducing agent dissociate the complex back to monomer |
| An unexpected higher molecular weight band in certain sarcoma-derived lines | PAX3 is subject to chromosomal rearrangement that generates fusion oncoproteins such as PAX3-FOXO1, which run larger than native PAX3 |
💡Expected PAX3 appearanceExpect a single band at approximately 53 kDa, matching both the predicted mass of the 479-residue PAX3 backbone and the empirically observed band, since the protein has no glycosylation, disulfide bonds, or cleavage sites that would shift its apparent size.
| Predicted mass from UniProt | sets the baseline expectation of about 53 kDa for the unmodified PAX3 backbone |
| Alternatively spliced isoforms Pax3, Pax3A, Pax3B, Pax3G, Pax3H, Pax3E and two unnamed variants | can produce additional bands of somewhat different size depending on which exons the antibody epitope falls within |
| Homodimer and PAX7 heterodimer formation on DNA | does not covalently link subunits since no inter-chain disulfide bonds are annotated, so SDS-PAGE still resolves PAX3 as a monomer |
| Non-glycosylated bacterial recombinant standard | runs essentially the same as native PAX3 because there is no glycosylation to lose in a non-eukaryotic expression system |
| Situation | Likely cause | Next action |
|---|---|---|
| Multiple bands | the 8 annotated PAX3 splice isoforms differ in exon content and can resolve as separate bands | confirm which isoform region the antibody targets and compare against isoform-specific controls |
| Band lower than expected | N-terminally truncated isoforms or partial degradation of the nuclear protein during lysis | add protease inhibitors, keep lysates cold, and use a nuclear extraction buffer to preserve full-length protein |
| Band higher than expected | chromosomal rearrangement generating fusion oncoproteins such as PAX3-FOXO1 in certain sarcoma cell lines, or incomplete dissociation of the non-covalent homodimer | confirm cell line identity and ensure samples are fully denatured and reduced with boiling and fresh reducing agent before loading |
| Weak or no signal | PAX3 expression is restricted to specific developmental and tissue contexts, so many cell lines express little or none | use lysates from known PAX3-expressing lines and enrich the nuclear fraction to concentrate the transcription factor |
| Broad smear instead of sharp band | closely spaced isoform bands can merge into a smear if not well resolved | run a higher percentage or gradient gel for longer to better separate isoform bands |
Experiment evidence
Western blot images showing PAX3 band
A00285-1 · PAX3
A00285-2 · PAX3
← swipe / scroll for more images →
Real WB data behind the band-size expectations in this section.
Sample controls for PAX3 Western blot
🧪For positive controls for PAX3 in Western blot, you can use a PAX3-overexpression lysate, such as HEK293 cells transiently transfected with a PAX3 expression construct, since no Human Protein Atlas tissue or cell line data is available to identify a reliable endogenous-expressing sample.
Positive control: PAX3-transfected HEK293 lysate
Negative control: untransfected/empty-vector HEK293 lysate
Loading controls: Also probe for GAPDH and β-actin as loading controls, and include a total-protein stain (e.g., stain-free gel, Ponceau S, or REVERT) to confirm even loading and transfer.
⚠️Feasibility: As a nuclear transcription factor with no HPA expression data and no evidence of ubiquitous expression, PAX3 has no validated endogenous positive tissue, so an overexpression system with a matched untransfected/vector-only negative control is the most feasible way to obtain clean controls.
Comprehensive Human Protein Atlas IHC scoring per tissue. Rows are taken directly from the HPA tissue chart — click any row's HPA link to view the source.
Positive expression · recommended positive controls
| Tissue | Cell type | Level | Evidence | Source |
|---|
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|
Section 3
Advanced PAX3 Western Blot Tips
Deeper troubleshooting and optimisation questions for PAX3, answered from its protein features.
Why does PAX3 match its predicted 53 kDa mass?
PAX3 has no signal peptide, propeptide, glycosylation, or disulfide bonds to add mass, so it runs close to its predicted 53 kDa. With minimal post-translational processing, little shift is expected; only phosphorylation at 3 residues may cause a slight upward smear rather than a distinct mobility shift.
Why might PAX3 blots show multiple bands?
UniProt lists 8 PAX3 isoforms (Pax3, Pax3A/B/G/H, isoforms 6 and 7, Pax3E) from alternative splicing. Antibodies targeting shared paired-box or homeodomain regions can detect several isoforms at once, giving bands at slightly different weights near 50-55 kDa. Check your antibody's immunogen against isoform sequences to interpret bands correctly.
Does PAX3 phosphorylation affect its Western blot mobility?
PAX3 is annotated as a phosphoprotein with 3 modified residues. Phosphorylation linked to neurogenesis and myogenesis signaling can cause minor mobility shifts or closely spaced doublets near 53 kDa. Phosphatase treatment of lysates helps confirm whether such bands reflect phosphorylation states rather than isoforms or degradation.
What blocking buffer works best for PAX3 detection?
Since PAX3 is a nuclear phosphoprotein, use 5% BSA rather than milk when probing with phospho-sensitive antibodies, since milk casein phosphoproteins can raise background. Standard 5% non-fat milk in TBST is otherwise adequate for total PAX3 antibodies targeting the paired box or homeodomain regions.
What transfer method to use for PAX3 Western blot?
PAX3 is a 53 kDa nuclear transcription factor with no unusual solubility issues, so standard wet or semi-dry transfer to PVDF works well. As a nuclear protein, ensure efficient lysis and transfer of nuclear extracts; extend transfer time slightly on larger gels to fully resolve closely spaced isoform bands.
Which loading control suits nuclear PAX3 quantitation?
Because PAX3 localizes to the nucleus, normalize band intensity to a nuclear loading control such as Lamin B1 or Histone H3 rather than cytoplasmic GAPDH or beta-actin, particularly with nuclear extraction protocols. This ensures quantitation reflects true nuclear protein loading rather than whole-cell lysate variability.
Why might rhabdomyosarcoma samples show larger PAX3 bands?
PAX3 carries the chromosomal rearrangement and proto-oncogene keywords, reflecting the PAX3-FOXO1 fusion seen in alveolar rhabdomyosarcoma. This fusion protein migrates larger than native 53 kDa PAX3, so an unexpected higher molecular weight band in tumor-derived samples may indicate fusion protein rather than nonspecific antibody binding.
Why do faint high molecular weight PAX3 bands appear?
PAX3 can form homodimers or heterodimers with PAX7 and interacts with PAXBP1 and DAXX. Incomplete denaturation or insufficient reducing conditions may leave residual complexes, appearing as faint bands roughly double the 53 kDa monomer. Thoroughly boil samples in SDS buffer with reducing agent to eliminate this artifact.
Boster reagents
Best PAX3 Western Blot Antibodies
BosterBio's PAX3 antibodies are among the best-performing WB antibodies on the market — well cited, thoroughly validated, and orthogonally cross-validated against negative tissues and complementary methods.
Real WB data
Anti-PAX3 Antibody Picoband®
Cat # A00285-1
Real WB data
Anti-PAX3 Antibody Picoband®
Cat # A00285-2
Our recommended anti-PAX3 antibodies are top-performing Boster reagents, widely cited and rigorously validated by western blot, with specificity orthogonally confirmed against negative tissue controls and complementary detection methods for reliable, reproducible results.
Which to pick: Both A00285-1 and A00285-2 include real western blot validation images for PAX3, so either antibody is a solid choice; select based on your preferred lot or format, as no further reactivity distinction is provided.
Source: BosterBio PAX3 gene-info card — filtered to Western-blot-capable antibodies; each card shows that product's actual WB validation figure.
References
- UniProt Consortium. UniProt entry P23760.
- Human Protein Atlas. PAX3 tissue expression.