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C9 · Western blot design guide
Design a Western Blot for C9
Real validated C9 Western blot protocols, expected-band and isoform facts, troubleshooting for weak or shifted signal, and recommended anti-C9 WB antibodies. Everything you need to plan the experiment before you commit precious samples.
Last reviewed: May 2026 · Scientific review: Boster Bio technical team
C9 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 | ~63.2 kDa | |
| Observed band | ~80 kDa | |
| Gel | 10–12% | |
| Positive control | Adipose tissue+4 more · see all | |
| Negative control | Adipose tissue+4 more · see all |
Important caveats
Reasons your observed band may differ from the expected size.
| PTM | Glycosylated + Phosphorylated | |
| Caveat | Glycosylation increases mass | |
| Regulation | Coagulation | |
| Isoform | 1 isoform(s) |
Section 1
Real Curated C9 Western Blot Protocols
Literature-validated Western blot parameters for C9 — gel percentage, transfer, blocking, antibody incubation and detection, extracted from published methods.
| Sample / lysate | human placenta . 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-Complement C9 antigen affinity purified polyclonal antibody (Catalog # A01010-2) 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 1:10000 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 Complement C9 at approximately 80KD. The expected band size for Complement C9 is at 63KD |
| 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, 1:10000 |
| Wash | TBS-0.1% Tween, 3 × 5 min |
| Detection | ECL |
| Exposure / imaging | Tanon 5200 |
| Observed band | 80 kDa |
Section 2
What Is the Expected C9 Western Blot Band Size?
C9 has a 63.2 kDa predicted backbone but runs at ~80 kDa due to N- and C-linked glycosylation across its 4 glycosylation sites.
| single band around 80 kDa on reducing SDS-PAGE | represents the mature, fully glycosylated C9 monomer, running well above the 63.2 kDa predicted mass |
| band sitting higher than the 63.2 kDa predicted mass | reflects added carbohydrate from 4 glycosylation sites, including complex-type N-glycans and C-mannosylation |
| little or no band in whole-cell lysate | C9 is a secreted plasma protein, so cell lysates contain little mature protein; plasma, serum, or conditioned media are more appropriate samples |
| high molecular weight smear or ladder near the top of the gel under non-reducing or native conditions | reflects C9 self-association into the ~20-chain membrane attack complex pore rather than the monomeric form |
| band slightly smaller than expected from the 559-aa full-length coding sequence | the 21-residue signal peptide is cleaved during secretion, so only the mature chain is present in secreted samples |
💡Expected C9 appearanceExpect a single band at ~80 kDa for mature, glycosylated C9 on reducing SDS-PAGE, above the 63.2 kDa predicted mass due to N- and C-mannosyl glycosylation.
| predicted mass (63.2 kDa, 559 aa) | sets the baseline unmodified backbone size before glycosylation or cleavage is factored in |
| N-glycosylation at Asn277 and complex-type Asn415 | adds carbohydrate mass that pushes the observed band up toward ~80 kDa and can broaden it |
| C-mannosylation at Trp48 and (partial) Trp51 | contributes additional glycan mass on top of N-glycosylation, further increasing apparent size |
| signal peptide cleavage (residues 1-21) | removes the N-terminal signal sequence during secretion so the mature chain runs slightly smaller than the full translated precursor |
| homooligomerization into the ~20-chain membrane attack complex | under non-reducing or native conditions can produce very high molecular weight species distinct from the ~80 kDa monomer seen on standard reducing gels |
| bacterial or non-glycosylated recombinant C9 standard | lacks native glycosylation and runs closer to the 63.2 kDa predicted mass, lower than plasma-derived native C9 |
| Situation | Likely cause | Next action |
|---|---|---|
| No band in lysate | C9 is secreted into plasma rather than retained intracellularly | use plasma, serum, or conditioned media instead of whole-cell lysate |
| Band higher than expected | N- and C-linked glycosylation adds substantial mass over the 63.2 kDa predicted backbone | confirm the ~80 kDa band is the expected native size, or treat with PNGase F to shift the band toward predicted mass |
| Broad smear instead of sharp band | heterogeneous glycan occupancy and structure across the 4 glycosylation sites | use a higher-percentage gel with a longer run to improve resolution, and confirm heterogeneity with glycosidase digestion |
| Band lower than expected | recombinant or bacterially expressed C9 lacks native glycosylation | verify the expression system and compare against a plasma-purified native C9 standard |
| Multiple bands | incomplete reduction of samples or residual membrane attack complex oligomers alongside monomeric C9 | ensure a fully reducing, denaturing sample buffer and boil samples thoroughly before loading |
| Fragments below expected size | proteolytic cleavage of C9 during membrane attack complex assembly or during sample handling | add protease inhibitors at lysis and minimize sample processing time before loading |
Experiment evidence
Western blot images showing C9 band
A01010-2 · C9
A01010-2 · C9
← swipe / scroll for more images →
Real WB data behind the band-size expectations in this section.
Sample controls for C9 Western blot
🧪For positive controls for C9 in Western blot, you can use human serum or plasma, since C9 is a secreted complement protein not well captured by the tissue panel supplied.
Positive control: Human serum/plasma
Negative control: Adipose tissue
Loading controls: Run GAPDH and β-actin blots alongside a total-protein stain (e.g., stain-free gel, Ponceau S, or REVERT) to confirm equal loading and transfer.
⚠️Feasibility: As a secreted plasma protein, C9 gives little signal in standard whole-cell tissue lysates, so favor conditioned medium, serum/plasma, or purified complement over lysate-based positive controls.
HPA tissue expression evidence for C9
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 |
|---|---|---|---|---|
| Adipose tissue | adipocytes | Not detected | Protein (IHC) | HPA → |
| Adrenal gland | glandular cells | Not detected | Protein (IHC) | HPA → |
| Appendix | glandular cells | Not detected | Protein (IHC) | HPA → |
| Bone marrow | hematopoietic cells | Not detected | Protein (IHC) | HPA → |
| Breast | adipocytes | Not detected | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Adipose tissue | adipocytes | Not detected | Protein (IHC) | HPA → |
| Adrenal gland | glandular cells | Not detected | Protein (IHC) | HPA → |
| Appendix | glandular cells | Not detected | Protein (IHC) | HPA → |
| Bone marrow | hematopoietic cells | Not detected | Protein (IHC) | HPA → |
| Breast | adipocytes | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced C9 Western Blot Tips
Deeper troubleshooting and optimisation questions for C9, answered from its protein features.
Why does C9 migrate near 80 kDa instead of 63.2 kDa?
C9's predicted mass of 63.2 kDa reflects the unmodified polypeptide after removal of the 21-residue signal peptide. Four N-glycosylation sites add substantial carbohydrate mass, and eleven disulfide bonds can create a more compact, SDS-resistant conformation that alters apparent migration. Together these features account for the ~80 kDa band commonly observed on reducing SDS-PAGE.
Should reducing agent be used for C9 SDS-PAGE?
Yes. C9 contains 11 disulfide bonds stabilizing its folded and oligomeric states. Omitting DTT or beta-mercaptoethanol leaves disulfide-linked structures intact, causing inconsistent mobility or high-molecular-weight smearing. Reducing conditions denature these bonds, giving a single, reproducible monomeric band suitable for size comparison against the predicted mass.
What causes high-molecular-weight bands above the monomer?
C9 self-associates into large homooligomers, with about 20 chains forming the beta-barrel membrane attack complex pore. If lysis or sample prep does not fully denature these SDS-resistant assemblies, high-molecular-weight bands or smears above the ~80 kDa monomer can appear, reflecting polymerized or membrane-inserted C9 rather than degradation products.
What blocking buffer works best for C9 detection?
Use BSA-based blocking rather than milk. C9 is a glycoprotein with four N-glycosylation sites, and milk contains glycoproteins and lectin-binding sugars that can raise background or cross-react with glycan-sensitive antibodies. 5% BSA in TBST gives cleaner blocking while avoiding interference with glycosylated epitopes.
What transfer method to use for C9 Western blot?
Standard wet or semi-dry transfer is sufficient since C9 runs at roughly 63-80 kDa, well within typical transfer efficiency ranges. Because 11 disulfide bonds can leave residual secondary structure, ensure samples are fully reduced and denatured before transfer, and use standard PVDF or nitrocellulose with typical transfer times for mid-sized proteins.
How should C9 signal be normalized in plasma samples?
C9 is a secreted plasma protein, so cytoplasmic housekeeping controls like GAPDH or actin are inappropriate for serum or plasma samples. Normalize instead to total protein stain (e.g., Ponceau S or REVERT) or a plasma-specific loading control, since C9 is not expressed intracellularly at consistent baseline levels like housekeeping genes.
Why might C9 appear as two distinct bands?
C9 exists both as a soluble secreted form and as a membrane-inserted form after incorporation into the beta-barrel membrane attack complex. Samples containing target cell membranes alongside serum/plasma C9 can show a doublet reflecting the soluble monomer versus the membrane-associated, transmembrane beta-strand-containing conformation, rather than degradation or nonspecific binding.
Boster reagents
Best C9 Western Blot Antibodies
BosterBio's C9 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-Complement C9 Antibody Picoband®
Cat # A01010-2
For Complement C9 Western blotting, we recommend Boster's rigorously validated anti-C9 antibody, a top-performing, widely cited reagent confirmed through orthogonal validation against negative-control tissues and complementary detection methods, delivering consistent, specific, publication-ready results.
Which to pick: Only one Boster C9 antibody is catalogued, A01010-2, making it the default choice; it has a genuine Western blot validation image confirming detection of Complement C9, supporting its use for routine WB work.
Source: BosterBio C9 gene-info card — filtered to Western-blot-capable antibodies; each card shows that product's actual WB validation figure.
References
- UniProt Consortium. UniProt entry P02748.
- Human Protein Atlas. C9 tissue expression.