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- Table of Contents
PSAP / Prosaposin · Western blot design guide
Design a Western Blot for PSAP
Real validated PSAP Western blot protocols, expected-band and isoform facts, troubleshooting for weak or shifted signal, and recommended anti-PSAP 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
PSAP 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 | ~58.1 kDa | |
| Gel | 12–15% (standard starting point) | |
| Positive control | Adipose tissue (IHC candidate; verify WB) +4 more | |
| Negative control | Suggested KO / knockdown lysate |
Important caveats
Reasons your observed band may differ from the expected size.
| PTM | Glycosylated + Cleaved | |
| Caveat | Processing-state controls | |
| Gene-set association | MSigDB C7 membership | |
| Isoform | 3 isoform(s) |
Section 1
Real Curated PSAP Western Blot Protocols
The M00937 protocol combines labelled catalog values with standard starting conditions. Published comparisons retain their own sample, reagent and detection scope.
| Sample / lysate | HepG2 cell lysate (catalog M00937) |
| 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 | M00937; 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 PSAP Western Blot Band Size?
The predicted precursor is 58.1 kDa; cleavage, N-linked glycosylation, and dimerization could affect migration, but no empirical band position is supplied.
| Band near 58.1 kDa | Compatible with the predicted full-length precursor; confirm identity with a specific control. |
| Band above 58.1 kDa | N-linked glycosylation could affect migration, but no shift is established. |
| Band near twice the monomer size under nonreducing conditions | Compatible with a disulfide-linked prosaposin dimer. |
| Band below the precursor size | Could reflect signal-peptide or propeptide cleavage. |
| Several distinct bands | Could reflect processing, dimerization, or Sap-mu-0, Sap-mu-6, and Sap-mu-9; isoform separation is unestablished. |
| Weak or absent band in whole-cell lysate | Secreted prosaposin may be depleted from the sampled cells. |
💡Expected PSAP appearanceUniProt predicts a 58.1 kDa precursor, while cleavage, N-linked glycosylation, and disulfide-linked dimerization may change migration; no empirical band size is supplied, so confirm band identity with controls.
| 58.1 kDa predicted precursor | Provides a sequence-based reference, not a measured band position. |
| N-linked sites at Asn80, Asn101, Asn215, Asn332, and Asn426 | Glycosylation may affect mobility; the size or visibility of any shift is unknown. |
| Disulfide-linked prosaposin dimer | May migrate near twice the monomer size under nonreducing or incompletely reducing conditions. |
| Sap-mu-0, Sap-mu-6, and Sap-mu-9 isoforms | May differ in size, but their masses and separation on a blot are unknown. |
| Signal peptide 1–16 and propeptide 17–59 | Cleavage can produce a smaller mature form than the precursor. |
| Situation | Likely cause | Next action |
|---|---|---|
| No band in lysate | Secreted prosaposin may be depleted from the sampled cells. | Check conditioned medium alongside lysate and use a positive control. |
| Band higher than expected | N-linked glycosylation or incomplete reduction of disulfide-linked dimers may contribute. | Compare reducing and nonreducing samples; assess glycosylation if needed. |
| Band lower than expected | Signal-peptide or propeptide cleavage may reduce precursor size. | Check antibody epitope coverage and confirm identity with a specific control. |
| Broad smear instead of sharp band | Different N-linked glycoforms could broaden migration. | Compare untreated and deglycosylated samples and verify specificity. |
| Multiple bands | Processing, disulfide-linked dimers, or isoforms could contribute. | Compare reducing conditions and use a specific band-identity control. |
| Fragments below expected size | Prosaposin processing could yield smaller products. | Check antibody epitope coverage and confirm bands with an independent antibody. |
Experiment evidence
Western blot images showing PSAP band
M00937 · PSAP
A00937-1 · PSAP
← swipe / scroll for more images →
Real WB data behind the band-size expectations in this section.
Sample controls for PSAP Western blot
🧪HPA-IHC candidate guidance (verify in WB): For positive controls for PSAP in Western blot, you can use adipose tissue, which has high HPA expression.
Positive control: Adipose tissue (IHC candidate; verify WB)
Negative control: Suggested KO / knockdown lysate
Loading controls: Run GAPDH, β-actin, and a total-protein stain such as Ponceau alongside the samples.
⚠️Feasibility: The supplied HPA data show no not-detected tissue, so a PSAP knockdown or KO line is needed for a clear negative control.
HPA tissue expression evidence for PSAP
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 |
|---|---|---|---|---|
| Adipose tissue | adipocytes | High | Protein (IHC) | HPA → |
| Adrenal gland | glandular cells | High | Protein (IHC) | HPA → |
| Appendix | glandular cells | High | Protein (IHC) | HPA → |
| Bone marrow | hematopoietic cells | High | Protein (IHC) | HPA → |
| Breast | glandular cells | High | Protein (IHC) | HPA → |
Lower expression tissues · IHC evidence, not confirmed WB-negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Esophagus | squamous epithelial cells | Medium | Protein (IHC) | HPA → |
| Oral mucosa | squamous epithelial cells | Medium | Protein (IHC) | HPA → |
| Ovary | ovarian stroma cells | Medium | Protein (IHC) | HPA → |
| Skeletal muscle | myocytes | Medium | Protein (IHC) | HPA → |
| Smooth muscle | smooth muscle cells | Medium | Protein (IHC) | HPA → |
Section 3
Advanced PSAP Western Blot Tips
Deeper troubleshooting and optimisation questions for PSAP, answered from its protein features.
How should PSAP 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 PSAP isoforms produce separate bands?
Isoforms · UniProt lists Sap-mu-0, Sap-mu-6, and Sap-mu-9. Relative to the canonical sequence, Sap-mu-6 has M→MDQ at position 259 and Sap-mu-9 has Q→QDQQ at position 260. These are UniProt coordinates; antibody or paper numbering may differ. The small sequence changes do not establish that the isoforms will resolve as separate bands.
Which PSAP glycosylation sites matter when assessing band mobility?
PTM · UniProt lists N-linked sites at Asn 80, 101, 215, 332, and 426, using canonical sequence coordinates; Asn 215 is annotated as complex. Compare matched samples before and after deglycosylation if testing whether glycans affect mobility. Site annotations alone cannot predict the size of any shift.
Does this guide establish induction of PSAP?
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 PSAP?
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 M00937 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 multiple PSAP bands be quantified?
Quantitation · Define which verified PSAP species the measurement includes, then use that same band selection across samples. The listed isoforms and monomer–dimer mixture make an unqualified sum of all visible bands hard to interpret. Confirm band identities before reporting combined PSAP intensity.
Why might PSAP migrate differently from its predicted 58.1 kDa?
Interpretation · The 58.1 kDa prediction is for the canonical sequence. UniProt annotates a signal peptide at 1–16, a propeptide at 17–59, and five N-linked glycosylation sites. These features may affect the form detected or its mobility, but they do not establish a specific band shift. No observed band size was supplied.
UniProt lists 12 disulfide bonds and describes prosaposin as a roughly equal mixture of monomers and disulfide-linked dimers. Compare reducing and nonreducing lanes when assessing a higher band. A change between conditions would support a disulfide-linked species, but band identity still needs confirmation.
Consider whether the antibody detects a form lacking the annotated signal peptide (1–16) or propeptide (17–59), using canonical UniProt coordinates. The supplied features do not establish the identity or expected size of a lower band. Check antibody epitope coverage before assigning it to a processed form.
UniProt lists 12 disulfide bonds and describes prosaposin as a roughly equal mixture of monomers and disulfide-linked dimers. Compare reducing and nonreducing lanes when assessing a higher band. A change between conditions would support a disulfide-linked species, but band identity still needs confirmation.
Consider whether the antibody detects a form lacking the annotated signal peptide (1–16) or propeptide (17–59), using canonical UniProt coordinates. The supplied features do not establish the identity or expected size of a lower band. Check antibody epitope coverage before assigning it to a processed form.
Boster reagents
PSAP 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-PSAP Rabbit Monoclonal Antibody
Cat # M00937
Real WB data
Anti-PSAP Antibody Picoband®
Cat # A00937-1
Two the supplier anti-PSAP antibodies are listed for human WB, each with a WB image. M00937 was shown with HepG2 lysate; A00937-1 was shown with A431, HeLa, HepG2, and MCF-7 lysates. The reported A00937-1 band is approximately 70 kDa versus 58 kDa expected.
Which to pick: For human HepG2 lysate, either antibody has a WB image. Choose A00937-1 if its A431, HeLa, or MCF-7 examples or detailed blot conditions are useful; M00937 provides a monoclonal HepG2 example. These images do not establish performance in other samples.
Source: BosterBio PSAP gene-info card — filtered to Western-blot-capable antibodies; each card shows that product's actual WB validation figure.
References
- UniProt Consortium. UniProt entry P07602.
- Human Protein Atlas. PSAP tissue expression.
- PMC9726671 — target-verified WB comparison
- PMC9569857 — target-verified WB comparison
- PMC12828107 — target-verified WB comparison