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- Table of Contents
F9 / Coagulation factor IX · Western blot design guide
Design a Western Blot for F9
Real validated F9 Western blot protocols, expected-band and isoform facts, troubleshooting for weak or shifted signal, and recommended anti-F9 WB antibodies. Everything you need to plan the experiment before you commit precious samples.
Evidence assembled September 2026 · For research use; verify linked source records and product datasheet before use
F9 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 | ~51.8 kDa | |
| Gel | 12–15% (standard starting point) | |
| Negative control | Suggested KO / knockdown lysate |
Important caveats
Reasons your observed band may differ from the expected size.
| PTM | Glycosylated + Phosphorylated | |
| Caveat | Modification-state controls | |
| Gene-set association | MSigDB Hallmark membership | |
| Isoform | 2 isoform(s) |
Section 1
Real Curated F9 Western Blot Protocols
The M00537 protocol combines labelled catalog values with standard starting conditions. Published comparisons retain their own sample, reagent and detection scope.
| Sample / lysate | human plasma lysate (catalog M00537) |
| Gel % | 12–15% (standard starting point) |
| Load | 20–30 µg total protein per lane; optimize for abundance (standard starting point) |
| Transfer | Standard semi-dry transfer; verify efficiency (standard starting point) |
| Membrane | 0.45 µm PVDF (standard starting point) |
| Blocking | 5% milk or 5% BSA in TBST (standard starting point) |
| Primary antibody | M00537; use the WB datasheet starting dilution (standard starting point) |
| Primary incubation | Overnight at 4 °C (standard starting point) |
| Secondary antibody | Species-matched HRP conjugate at validated dilution (standard starting point) |
| Secondary incubation | 1 h at room temperature (standard starting point) |
| Wash | 3 × 5 min in TBST (standard starting point) |
| Detection | ECL; bracket exposures to avoid saturation (standard starting point) |
Section 2
What Is the Expected F9 Western Blot Band Size?
Factor IX has a predicted 51.8 kDa precursor; cleavage, glycosylation and disulfide-linked chains could affect migration, but no empirical band position is supplied.
| Band near 51.8 kDa | Compatible with the predicted precursor mass; identity requires a control. |
| Band below 51.8 kDa | May reflect signal peptide or propeptide removal, or proteolytic processing. |
| Nonreducing band above reduced chain bands | May reflect disulfide-linked light and heavy chains. |
| Diffuse band | Variable glycosylation is possible, but the listed sites do not establish a visible smear. |
| Multiple bands | Processing or isoforms 1 and 2 are possible; distinct isoform bands are not established. |
| Little or no band in whole-cell lysate | Factor IX is secreted. |
💡Expected F9 appearanceThe 51.8 kDa UniProt mass is for the precursor; cleavage, glycosylation and chain association may affect migration, but no empirical band size is supplied, so confirm identity with appropriate controls.
| 51.8 kDa predicted precursor mass | Provides a sequence-based reference, not a validated band position. |
| Signal peptide 1–28 and propeptide 29–46 | Their removal yields a smaller mature protein than the precursor. |
| N-linked glycosylation at Asn203 and Asn213 | May alter apparent migration; no shift size is established. |
| O-linked glycosylation at Thr85, Ser99, Ser107, alternate Thr205, Thr215 and Thr225 | May affect migration; these sites alone do not establish a visible shift or smear. |
| Disulfide-linked light and heavy chains | May migrate together under nonreducing conditions and separately after reduction. |
| Isoforms 1 and 2 | May differ in size, but distinct band positions are not supplied. |
| Situation | Likely cause | Next action |
|---|---|---|
| No band in lysate | Factor IX is secreted. | Check plasma or conditioned medium and include a positive control. |
| Band higher than expected | Incomplete reduction may retain disulfide-linked chains; glycosylation may also affect migration. | Compare reducing and nonreducing lanes with a Factor IX positive control. |
| Band lower than expected | Signal peptide, propeptide or further proteolytic cleavage may remove sequence. | Check antibody epitope and compare precursor and processed samples. |
| Broad smear instead of sharp band | Variable glycosylation is possible, although the sites alone do not establish a smear. | Compare matched glycan-treatment controls and a Factor IX positive control. |
| Multiple bands | Processing, disulfide-linked chains or isoforms 1 and 2 may contribute. | Compare reducing conditions and confirm bands with an independent Factor IX antibody. |
| Fragments below expected size | Proteolytic processing may produce light and heavy chains. | Compare reducing and nonreducing lanes using antibodies with known epitopes. |
Experiment evidence
Western blot images showing F9 band
M00537 · F9
← swipe / scroll for more images →
Real WB data behind the band-size expectations in this section.
Sample controls for F9 Western blot
🧪For positive controls for F9 in Western blot, you can use conditioned medium from an independently verified F9-expressing source; HPA identifies no positive tissue or cell.
Positive control: No high/medium HPA tissue identified
Negative control: Suggested KO / knockdown lysate
Loading controls: Run GAPDH, β-actin, and a total-protein stain alongside the samples.
⚠️Feasibility: F9 is secreted, so conditioned medium may be more useful than whole-cell lysate, but HPA provides no tissue controls.
HPA tissue expression evidence for F9
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.
Higher expression tissues · candidate positive controls from IHC
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| No high/medium HPA tissues identified in the supplied evidence. | ||||
Lower expression tissues · IHC evidence, not confirmed WB-negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| No lower-expression tissue rows available in the supplied evidence. | ||||
Section 3
Advanced F9 Western Blot Tips
Deeper troubleshooting and optimisation questions for F9, answered from its protein features.
How should F9 band migration be interpreted?
Band shift · Use the separately labelled calculated mass and catalog-observed evidence above. A sequence annotation does not establish an observed migration shift. Verify target identity with orthogonal controls.
Could F9 isoforms produce different bands?
Isoforms · UniProt lists isoforms 1 and 2; isoform 2 lacks residues 93..130 in precursor coordinates. That removes annotated glycosylation sites 99 and 107 and modified residues 110 and 114. Check which isoform your antibody recognizes before assigning a second band. The sequence difference alone does not establish its apparent size.
Which F9 glycosylation sites matter when interpreting band patterns?
PTM · UniProt precursor sites are O-linked 85, 99, 107, 205, 215, and 225, plus N-linked 203 and 213. Site 205 has an alternate O-linked annotation. Glycosylation may affect migration, but the listed sites do not establish which forms are present in your sample or how far they migrate.
UniProt annotates phosphoserine at precursor positions 114 and 204 and alternate phosphothreonine at 205. It also lists sulfotyrosine 201, hydroxyaspartate 110, and 4-carboxyglutamate at 53, 54, 61, 63, 66, 67, 72, 73, 76, 79, 82, and 86. These annotations support considering modification state, but do not demonstrate a visible band shift.
UniProt annotates phosphoserine at precursor positions 114 and 204 and alternate phosphothreonine at 205. It also lists sulfotyrosine 201, hydroxyaspartate 110, and 4-carboxyglutamate at 53, 54, 61, 63, 66, 67, 72, 73, 76, 79, 82, and 86. These annotations support considering modification state, but do not demonstrate a visible band shift.
Does UniProt support inducing F9 before Western blotting?
Induction · The supplied features identify F9 as a secreted blood-coagulation protein, but specify no induction condition or treatment response. Use the sample's F9 expression and secretion context to plan collection; these features do not justify a particular inducer or predict an increase in band intensity.
How should transfer be checked for F9?
Transfer · Standard workflow guidance: verify transfer efficiency for the intended target size before interpreting a weak signal. Use total-protein assessment and optimize transfer for the membrane, gel and apparatus; the labelled catalog values take precedence.
How should blocking be optimized?
Blocking · Standard workflow guidance: follow the M00537 datasheet where specified. Otherwise compare 5% milk or 5% BSA in TBST; for a phospho-specific assay start with BSA. Optimize background and specific signal with matched controls.
Where should F9 be measured for Western blot quantitation?
Quantitation · UniProt identifies F9 as secreted. Choose a sample fraction that contains the F9 species you intend to measure, and quantify the same band or band group across samples. Its processing, isoforms, and modifications mean that combining distinct bands into one value requires a defined interpretation.
Why might F9 migrate differently from its predicted 51.8 kDa?
Interpretation · The 51.8 kDa prediction describes the precursor. UniProt lists a signal peptide at 1..28, a propeptide at 29..46, and eight glycosylation sites. Processing and modification can affect migration, but these features alone cannot predict a visible shift or explain a particular band; no observed band size was supplied. Coordinates here refer to the UniProt precursor.
F9 has a signal peptide at precursor positions 1..28 and a propeptide at 29..46. UniProt also describes a disulfide-linked light-chain and heavy-chain heterodimer. Consider precursor processing and whether the sample was reduced when assigning bands; the supplied features do not give chain cleavage coordinates or expected band sizes.
F9 has a signal peptide at precursor positions 1..28 and a propeptide at 29..46. UniProt also describes a disulfide-linked light-chain and heavy-chain heterodimer. Consider precursor processing and whether the sample was reduced when assigning bands; the supplied features do not give chain cleavage coordinates or expected band sizes.
Boster reagents
F9 Western Blot Antibodies
Catalog antibodies with Western blot application and product-specific WB images. Evaluate suitability with the reported sample, controls and experimental conditions.
Real WB data
Anti-Factor IX Rabbit Monoclonal Antibody
Cat # M00537
M00537 is an anti-Factor IX rabbit monoclonal antibody listed for human reactivity. Its Western blot image shows Factor IX expression in human plasma lysate. The supplied evidence does not establish performance in other sample types or species.
Which to pick: M00537 is the only listed F9 antibody. Choose it when working with human samples, especially plasma lysate, the context shown in its Western blot image. Check suitability separately for other sample types.
Source: BosterBio F9 gene-info card — filtered to Western-blot-capable antibodies; each card shows that product's actual WB validation figure.
References
- UniProt Consortium. UniProt entry P00740.
- Human Protein Atlas. F9 tissue expression.
- PMC12882450 — target-verified WB comparison
- PMC7141619 — target-verified WB comparison