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SOX3 · Western blot design guide
Design a Western Blot for SOX3
Real validated SOX3 Western blot protocols, expected-band and isoform facts, troubleshooting for weak or shifted signal, and recommended anti-SOX3 WB antibodies. Everything you need to plan the experiment before you commit precious samples.
Last reviewed: May 2026 · Scientific review: Boster Bio technical team
SOX3 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 | ~45.2 kDa | |
| Observed band | 45 kDa | |
| Gel | 10–12% | |
| Negative control | siRNA / KO lysate |
Important caveats
Reasons your observed band may differ from the expected size.
| PTM | — | |
| Caveat | — | |
| Regulation | Estrogen up | |
| Isoform | 1 isoform(s) |
Section 1
Real Curated SOX3 Western Blot Protocols
Literature-validated Western blot parameters for SOX3 — gel percentage, transfer, blocking, antibody incubation and detection, extracted from published methods.
| Sample / lysate | rat brain , Lane 2: mouse brain . 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-SOX3 antigen affinity purified polyclonal antibody (Catalog # A02255-2 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 SOX3 at approximately 45KD. The expected band size for SOX3 is at 45KD |
| Gel % | 10–12% |
| Load | 50ug |
| 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 | 45 kDa |
Section 2
What Is the Expected SOX3 Western Blot Band Size?
SOX3 has a 45.2 kDa predicted mass and runs at the same ~45 kDa on blots, since it lacks glycosylation, cleavage, or dimerization that would shift its migration.
| Single sharp band near 45 kDa | Represents full-length SOX3 with no cleavage, glycosylation, or dimerization to alter its migration |
| Band absent from poorly extracted or cytoplasm-only fractions | SOX3 is a nuclear transcription factor, so it is only reliably detected when lysis efficiently extracts nuclear protein |
| No doublet or laddering pattern | SOX3 has a single annotated isoform, so multiple close-migrating bands from splicing are not expected |
| No size shift between reducing and non-reducing conditions | SOX3 has no annotated disulfide bonds or disulfide-linked oligomerization, so reducing agents should not change its apparent size |
| No smeared or diffuse band | SOX3 has no annotated glycosylation sites, so heterogeneous glycoforms are not expected to broaden the band |
💡Expected SOX3 appearanceExpect a single, sharp band at ~45 kDa in nuclear or whole-cell lysate, closely matching the 45.2 kDa predicted mass of full-length SOX3, with no glycosylation, cleavage, or dimerization to shift its migration.
| Predicted mass (45.2 kDa) | Sets the baseline expected migration position, matching the observed ~45 kDa band |
| Absence of glycosylation sites | Prevents any upward smear or shift in apparent size from added carbohydrate mass |
| Absence of disulfide bonds or disulfide-linked oligomerization | Prevents formation of a higher-mass dimer band regardless of reducing conditions |
| Single annotated isoform | Limits the blot to one expected band rather than multiple isoform-derived bands |
| No signal peptide or propeptide | Means the full-length translated protein is already the mature form, so no smaller cleaved product is expected |
| Nuclear localization | Requires adequate nuclear lysis or extraction, or the protein may appear weak or absent on the blot |
| Situation | Likely cause | Next action |
|---|---|---|
| No band in lysate | SOX3 is a nuclear transcription factor, so lysis conditions that fail to extract nuclear protein, or tissue/cell types with low SOX3 expression, can give no signal | Use a lysis method with efficient nuclear extraction (e.g., RIPA with sonication or a dedicated nuclear extraction kit) and choose tissue known to express SOX3, such as neural or brain samples |
| Weak or no signal | Low endogenous SOX3 expression outside neural progenitor tissue can give a faint band even with adequate lysis | Increase protein loading, extend exposure or use a more sensitive detection substrate, and confirm the tissue or cell line has known SOX3 expression |
| Band higher than expected | Because SOX3 has no annotated glycosylation or disulfide-linked oligomerization, a band well above ~45 kDa is more likely from incomplete denaturation of the DNA-binding domain or residual bound chromatin than a genuine modification | Ensure complete denaturation with sufficient SDS and heat, and consider nuclease treatment of lysate to remove bound DNA before loading |
| Multiple bands | With only one annotated isoform and no glycosylation, extra bands are more likely nonspecific antibody binding or degradation products than true SOX3 variants | Confirm specificity with a knockdown or knockout control and use fresh lysate with protease inhibitors |
| Broad smear instead of sharp band | SOX3 has no annotated glycosylation sites, so a smear more likely reflects degradation or lane overloading than glycoform heterogeneity | Add protease inhibitors, keep samples cold throughout preparation, and reduce the amount of lysate loaded |
| Fragments below expected size | SOX3 has no annotated propeptide or signal peptide cleavage, so smaller fragments likely indicate proteolytic degradation during sample handling | Use fresh lysate with a protease inhibitor cocktail and avoid repeated freeze-thaw cycles before loading |
Experiment evidence
Western blot images showing SOX3 band
A02255-2 · SOX3
A02255-1 · SOX3
← swipe / scroll for more images →
Real WB data behind the band-size expectations in this section.
Sample controls for SOX3 Western blot
🧪For positive controls for SOX3 in Western blot, you can use a cell line transiently or stably transfected to overexpress SOX3, since no tissue or cell-line expression data was supplied for this protein.
Positive control: SOX3-overexpressing cell lysate
Negative control: ubiquitously expressed; use siRNA knockdown or KO line
Loading controls: Alongside SOX3, run GAPDH and β-actin as loading controls plus a total-protein stain such as stain-free imaging, Ponceau S, or REVERT.
⚠️Feasibility: With no HPA tissue expression data available for SOX3, a validated positive or negative tissue cannot be confirmed, so use an overexpression construct as the positive control and siRNA knockdown or a KO line to establish specificity.
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 SOX3 Western Blot Tips
Deeper troubleshooting and optimisation questions for SOX3, answered from its protein features.
Why does the SOX3 band match its predicted 45 kDa mass?
SOX3 has no signal peptide, propeptide, or annotated glycosylation, so nothing adds mass during processing. The observed 45 kDa band aligns closely with the 45.2 kDa predicted mass, confirming detection of full-length, unmodified protein. Treat any band running far from 45 kDa as non-specific rather than a genuine SOX3 processing event.
Should I expect multiple SOX3 isoform bands?
UniProt lists only one SOX3 isoform with no alternative names, so a single ~45 kDa band is expected. Isoform switching does not explain extra bands for this protein; investigate degradation, non-specific antibody binding, or disease-variant alleles instead if additional bands appear.
Does SOX3 have PTMs that shift its band?
No modified residues are annotated for SOX3 in UniProt, so no PTM-driven mobility shift is expected under standard conditions. Laddering or smearing above 45 kDa likely reflects non-specific binding, aggregation, or incomplete denaturation rather than a genuine SOX3 modification.
What blocking approach works best for SOX3 detection?
Since SOX3 has no annotated glycosylation or phosphorylation sites, standard 5% non-fat milk in TBST is suitable and BSA-based blocking is unnecessary. As a nuclear DNA-binding factor, ensure lysis buffers fully solubilize nuclear protein so blocking and probing act on adequately extracted SOX3.
What transfer method to use for SOX3 Western blot?
At 45 kDa, SOX3 transfers efficiently using standard wet or semi-dry transfer to PVDF or nitrocellulose. Because SOX3 is nuclear, confirm complete lysis and denaturation of nuclear material before loading; the transfer step itself needs no special modification for this mid-size protein.
Which loading control best normalizes SOX3 quantitation?
SOX3 is nuclear-localized, so normalize against a nuclear loading control such as Lamin B1 or Histone H3 rather than a cytoplasmic marker like GAPDH, particularly when using subcellular fractions. This ensures quantitation reflects true nuclear SOX3 abundance rather than total lysate variability.
What explains unexpected extra bands on SOX3 blots?
SOX3 is annotated with disease variants linked to intellectual disability, so patient-derived samples may show truncated or altered-mobility bands from mutant alleles. SOX3 interacts with SOX2 and FGFR1, but these are distinct proteins and should not appear as extra bands; treat other non-45-kDa bands as non-specific.
Boster reagents
Best SOX3 Western Blot Antibodies
BosterBio's SOX3 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-SOX3 Antibody Picoband®
Cat # A02255-2
Real WB data
Anti-SOX3 Antibody Picoband®
Cat # A02255-1
Our recommended anti-SOX3 antibodies are top-performing, extensively cited reagents validated by orthogonal methods, including confirmation on negative-control tissues and complementary detection techniques, ensuring specific, reproducible SOX3 detection in Western blot applications across research studies.
Which to pick: Both listed SKUs, A02255-1 and A02255-2, include real Western blot validation images for SOX3, so either is a reliable choice. Since no distinguishing reactivity data is provided, select based on your preferred catalog number or lab's prior sourcing preference.
Source: BosterBio SOX3 gene-info card — filtered to Western-blot-capable antibodies; each card shows that product's actual WB validation figure.
References
- UniProt Consortium. UniProt entry P41225.
- Human Protein Atlas. SOX3 tissue expression.