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- Table of Contents
CPE / Carboxypeptidase E · Western blot design guide
Design a Western Blot for CPE
Real validated CPE Western blot protocols, expected-band and isoform facts, troubleshooting for weak or shifted signal, and recommended anti-CPE 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
CPE 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 | ~53.2 kDa | |
| Gel | 12–15% (standard starting point) | |
| Positive control | Appendix (IHC candidate; verify WB) +4 more | |
| Negative control | Adipose tissue (IHC candidate; verify WB) |
Important caveats
Reasons your observed band may differ from the expected size.
| PTM | Glycosylated + Cleaved | |
| Caveat | Maturation-state controls | |
| Gene-set association | MSigDB Hallmark membership | |
| Isoform | 2 isoform(s) |
Section 1
Real Curated CPE Western Blot Protocols
The A01407 protocol combines labelled catalog values with standard starting conditions. Published comparisons retain their own sample, reagent and detection scope.
| Sample / lysate | Target-positive lysate and matched negative control (standard starting point) |
| 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 | A01407; 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 CPE Western Blot Band Size?
CPE has a predicted precursor mass of 53.2 kDa; cleavage, glycosylation, and isoforms may affect bands, but no migration pattern is demonstrated here.
| Band near 53.2 kDa | consistent with the predicted precursor size, pending identity confirmation |
| Band below 53.2 kDa | could reflect signal peptide or propeptide cleavage |
| Band above 53.2 kDa | could reflect N-linked glycosylation at Asn139 or Asn390; a visible shift is unproven |
| Several bands | could reflect processing or isoforms 1 and 2; distinct isoform bands are unproven |
| Faint or absent lysate band | CPE may be secreted or concentrated in secretory vesicles |
💡Expected CPE appearanceThe predicted precursor mass is 53.2 kDa; cleavage and N-linked glycosylation may affect migration, but no empirical band size is supplied, so confirm band identity with appropriate controls.
| Predicted precursor mass | 53.2 kDa before processing or modification |
| N-linked glycosylation at Asn139 | may increase apparent size; a visible shift is unproven |
| N-linked glycosylation at Asn390 | may increase apparent size; a visible shift is unproven |
| Signal peptide at residues 1–25 | cleavage makes the mature protein smaller than the precursor |
| Propeptide at residues 26–42 | cleavage further reduces size relative to the precursor |
| Isoforms 1 and 2 | may differ in size; their masses and band separation are unknown |
| Situation | Likely cause | Next action |
|---|---|---|
| No band in lysate | CPE can be secreted or enriched in secretory vesicles | check conditioned medium and a secretory vesicle fraction with suitable controls |
| Band higher than expected | N-linked glycosylation is possible at Asn139 and Asn390 | compare matched untreated and PNGase F treated samples, then confirm band identity |
| Band lower than expected | signal peptide or propeptide cleavage may reduce size | check antibody epitope coverage and confirm the band with a CPE depletion control |
| Broad smear instead of sharp band | variable N-linked glycosylation is possible but unproven | compare matched untreated and PNGase F treated samples |
| Multiple bands | processing or isoforms 1 and 2 may contribute; band separation is unproven | confirm which bands depend on CPE using depletion and check antibody epitope coverage |
Experiment evidence
Western blot images showing CPE band
A01407 · CPE
A30595 · CPE
A30595 · CPE
A30595 · CPE
A30595 · CPE
← swipe / scroll for more images →
Real WB data behind the band-size expectations in this section.
Sample controls for CPE Western blot
🧪HPA-IHC candidate guidance (verify in WB): For positive controls for CPE in Western blot, you can use appendix tissue, which shows high HPA expression.
Positive control: Appendix (IHC candidate; verify WB)
Negative control: Adipose tissue (IHC candidate; verify WB)
Loading controls: Run GAPDH, β-actin, and a total-protein stain alongside the samples.
⚠️Feasibility: Because CPE is secreted, conditioned medium may provide a clearer signal than whole-cell lysate.
HPA tissue expression evidence for CPE
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 |
|---|---|---|---|---|
| Appendix | endocrine cells | High | Protein (IHC) | HPA → |
| Cerebellum | Bergmann glia - cytoplasm/membrane | High | Protein (IHC) | HPA → |
| Colon | endocrine cells | High | Protein (IHC) | HPA → |
| Duodenum | endocrine cells | High | Protein (IHC) | HPA → |
| Hippocampus | neuronal cells | High | 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 → |
| Bone marrow | hematopoietic cells | Not detected | Protein (IHC) | HPA → |
| Breast | adipocytes | Not detected | Protein (IHC) | HPA → |
| Caudate | glial cells | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced CPE Western Blot Tips
Deeper troubleshooting and optimisation questions for CPE, answered from its protein features.
How should CPE 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 isoform 2 produce a different CPE band?
Isoforms · UniProt lists isoforms 1 and 2. Isoform 2 lacks canonical residues 1..36, including the annotated signal peptide and part of the propeptide. It could therefore differ in size, but the supplied features do not establish its abundance or apparent position on a blot. Coordinates here follow the supplied UniProt canonical sequence.
Isoform 1 is annotated in secretory vesicles, associated with secretory vesicle membranes as a peripheral membrane protein, and secreted. Consider the fraction being tested when interpreting its detection; the supplied location annotation does not describe isoform 2.
Isoform 1 is annotated in secretory vesicles, associated with secretory vesicle membranes as a peripheral membrane protein, and secreted. Consider the fraction being tested when interpreting its detection; the supplied location annotation does not describe isoform 2.
What do CPE's glycosylation sites suggest?
PTM · The supplied UniProt canonical coordinates identify N-linked glycosylation sites at Asn139 and Asn390. Comparing treated and untreated samples could test whether glycosylation contributes to a band pattern. Site annotation alone does not prove either site is occupied in your samples or causes a visible shift.
Does this guide establish induction of CPE?
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 CPE?
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 A01407 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 CPE bands be quantified across samples?
Quantitation · Quantify a consistently identified band in comparable sample fractions. Document whether the measured band represents a particular processed or glycosylated form, since CPE has annotated processing regions and two glycosylation sites. The supplied features do not identify a single observed band for quantitation.
Why might CPE migrate differently from 53.2 kDa?
Interpretation · The 53.2 kDa prediction is a reference, not an observed band. CPE has a signal peptide, a propeptide, and two N-linked glycosylation sites. Processing or glycosylation could affect apparent mass, but these features alone do not establish a visible shift.
The supplied UniProt canonical sequence marks a signal peptide at residues 1..25 and a propeptide at 26..42. Compare candidate bands with the full-length prediction cautiously; these features do not establish which processed forms are present in your sample.
Check candidate bands against the 53.2 kDa prediction, residues 1..25 and 26..42 annotated for processing, N-linked sites Asn139 and Asn390, and isoform 2's deletion of residues 1..36. These are possible interpretations, not proof of band identity; the supplied record provides no observed band position.
The supplied UniProt canonical sequence marks a signal peptide at residues 1..25 and a propeptide at 26..42. Compare candidate bands with the full-length prediction cautiously; these features do not establish which processed forms are present in your sample.
Check candidate bands against the 53.2 kDa prediction, residues 1..25 and 26..42 annotated for processing, N-linked sites Asn139 and Asn390, and isoform 2's deletion of residues 1..36. These are possible interpretations, not proof of band identity; the supplied record provides no observed band position.
Boster reagents
CPE 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-CPE/Carboxypeptidase E Antibody
Cat # A01407
Real WB data
Anti-CPE/Carboxypeptidase E Antibody
Cat # A30595
The catalog reports two anti-CPE antibodies, A01407 and A30595, with stated human, mouse, and rat reactivity. Each has a WB image: A01407 using mouse brain cells and A30595 using K562 cells. These examples document specific tested contexts, not validation across all listed species.
Which to pick: Choose A01407 for a mouse brain cell example or A30595 for a K562 cell example. Both list human, mouse, and rat reactivity and have WB images; the supplied evidence does not establish a broader performance preference.
Source: BosterBio CPE gene-info card — filtered to Western-blot-capable antibodies; each card shows that product's actual WB validation figure.
References
- UniProt Consortium. UniProt entry P16870.
- Human Protein Atlas. CPE tissue expression.
- PMC5256889 — target-verified WB comparison