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- Table of Contents
BPI / Bactericidal permeability-increasing protein · Western blot design guide
Design a Western Blot for BPI
Real validated BPI Western blot protocols, expected-band and isoform facts, troubleshooting for weak or shifted signal, and recommended anti-BPI 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
BPI 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 | ~53.9 kDa | |
| Gel | 12–15% (standard starting point) | |
| Positive control | Bone marrow (IHC candidate; verify WB) | |
| Negative control | Adipose tissue (IHC candidate; verify WB) |
Important caveats
Reasons your observed band may differ from the expected size.
| PTM | Glycosylated + Cleaved | |
| Caveat | Modification-state controls | |
| Gene-set association | MSigDB C7 membership | |
| Isoform | 1 isoform(s) |
Section 1
Real Curated BPI Western Blot Protocols
The M01444 protocol combines labelled catalog values with standard starting conditions. Published comparisons retain their own sample, reagent and detection scope.
| Sample / lysate | THP1 lysate (catalog M01444) |
| 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 | M01444; 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 BPI Western Blot Band Size?
Full-length BPI is predicted at 53.9 kDa; processing, Asn380 glycosylation, and disulfide-linked dimerization could affect migration, but no empirical band is supplied.
| Band near 53.9 kDa | Compatible with the predicted full-length BPI monomer; confirm identity with controls |
| Band below the precursor position | May reflect removal of the 1–31 signal peptide; mature migration is not supplied |
| Band near twice the monomer size under nonreducing conditions | Compatible with disulfide-linked BPI homodimer |
| Little or no band in whole-cell lysate | BPI may be secreted or associated with granule membranes |
💡Expected BPI appearanceThe 53.9 kDa UniProt value predicts full-length BPI, while signal-peptide cleavage, Asn380 N-linked glycosylation, and disulfide-linked dimerization may affect migration; no empirical band size is supplied, so confirm band identity with controls.
| Predicted full-length mass | 53.9 kDa is the sequence-based precursor reference |
| Asn380 N-linked glycosylation | May affect apparent migration; the size of any shift is unknown |
| Disulfide-linked homodimer | May appear near twice the monomer size under nonreducing conditions |
| Signal peptide at residues 1–31 | Its removal produces a smaller mature protein than the precursor |
| Situation | Likely cause | Next action |
|---|---|---|
| No band in lysate | BPI is secreted and associated with granule membranes | Check conditioned medium and a granule-enriched fraction with a positive control |
| Band higher than expected | Disulfide-linked homodimer may persist with incomplete reduction | Compare reducing and nonreducing samples |
| Band lower than expected | The 1–31 signal peptide may have been removed | Compare with a precursor control and verify the antibody's recognized region |
| Multiple bands | Monomer and disulfide-linked homodimer may coexist | Compare reducing and nonreducing lanes and verify band identity |
| Weak or no signal | Secreted or granule-associated BPI may be scarce in the sampled fraction | Check a suitable positive control and test medium or granule-enriched material |
Experiment evidence
Western blot images showing BPI band
M01444 · BPI
← swipe / scroll for more images →
Real WB data behind the band-size expectations in this section.
Sample controls for BPI Western blot
🧪HPA-IHC candidate guidance (verify in WB): For positive controls for BPI in Western blot, you can use bone marrow tissue, which HPA scores as medium.
Positive control: Bone marrow (IHC candidate; verify WB)
Negative control: Adipose tissue (IHC candidate; verify WB)
Loading controls: Run GAPDH, β-actin, and a total-protein stain such as Ponceau alongside the samples.
⚠️Feasibility: Because BPI is secreted and granule-associated, whole-cell lysate signal may vary.
HPA tissue expression evidence for BPI
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 |
|---|---|---|---|---|
| Bone marrow | hematopoietic cells | Medium | Protein (IHC) | HPA → |
Lower expression tissues · IHC evidence, not confirmed WB-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 → |
| Breast | adipocytes | Not detected | Protein (IHC) | HPA → |
| Bronchus | respiratory epithelial cells | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced BPI Western Blot Tips
Deeper troubleshooting and optimisation questions for BPI, answered from its protein features.
How should BPI 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.
Are BPI isoforms expected to create multiple bands?
Isoforms · Only one isoform is listed, with no alternative sequence supplied. The provided features therefore do not support assigning multiple bands to annotated isoforms.
Which BPI glycosylation site should I consider?
PTM · UniProt lists one N-linked glycosylation site, at asparagine 380 in UniProt numbering. Compare untreated and deglycosylated samples to test whether glycosylation affects mobility; the annotation alone does not establish a band shift.
Does this guide establish induction of BPI?
Induction · No general induction response is established by this guide. A pathway or gene-set association is not evidence of induction in a particular specimen. Verify the relevant treatment and control in a target-specific experiment.
How should transfer be checked for BPI?
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 M01444 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.
How should BPI be quantified?
Quantitation · Standard workflow guidance: quantify only a validated target band within the linear exposure range. Use consistent sample preparation and loading, retain biological replicates, and avoid interpreting saturation or loading differences as regulation.
Why might BPI migrate differently from 53.9 kDa?
Interpretation · The 53.9 kDa prediction includes the full sequence. BPI has a signal peptide at residues 1..31 and an N-linked glycosylation site at UniProt position 380. Signal peptide removal and glycosylation may affect apparent mass, but these features alone cannot predict a visible shift. No observed band size is supplied.
BPI is listed as a monomer and a disulfide-linked homodimer. Compare reducing and nonreducing samples: a larger species that changes under reducing conditions may be consistent with the annotated dimer. Confirm its identity before assigning it to BPI.
BPI is annotated as secreted and as membrane-associated in polymorphonuclear leukocyte granules. Consider both extracellular material and granule-containing cellular fractions when choosing samples.
Use the same sample fraction and reducing conditions for each comparison. BPI can be secreted or associated with granule membranes, and it can form a disulfide-linked homodimer, so changes in fraction or sample preparation can change which BPI species are measured.
Check whether its behavior is consistent with signal peptide removal, glycosylation at UniProt asparagine 380, or the annotated disulfide-linked homodimer. None of these features alone identifies an unexpected band or establishes its apparent mass.
BPI is listed as a monomer and a disulfide-linked homodimer. Compare reducing and nonreducing samples: a larger species that changes under reducing conditions may be consistent with the annotated dimer. Confirm its identity before assigning it to BPI.
BPI is annotated as secreted and as membrane-associated in polymorphonuclear leukocyte granules. Consider both extracellular material and granule-containing cellular fractions when choosing samples.
Use the same sample fraction and reducing conditions for each comparison. BPI can be secreted or associated with granule membranes, and it can form a disulfide-linked homodimer, so changes in fraction or sample preparation can change which BPI species are measured.
Check whether its behavior is consistent with signal peptide removal, glycosylation at UniProt asparagine 380, or the annotated disulfide-linked homodimer. None of these features alone identifies an unexpected band or establishes its apparent mass.
Boster reagents
BPI 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-BPI Rabbit Monoclonal Antibody
Cat # M01444
M01444 is a human-reactive anti-BPI rabbit monoclonal antibody with a Western blot image showing BPI expression in THP1 lysate. The supplied evidence does not establish performance in other samples or species.
Which to pick: M01444 is the only listed option. Its WB image uses THP1 lysate, making it the evidence-backed choice for that sample context; suitability for other samples is not established here.
Source: BosterBio BPI gene-info card — filtered to Western-blot-capable antibodies; each card shows that product's actual WB validation figure.
References
- UniProt Consortium. UniProt entry P17213.
- Human Protein Atlas. BPI tissue expression.
- PMC5559428 — target-verified WB comparison
- PMC7379883 — target-verified WB comparison
- PMC7858664 — target-verified WB comparison