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PPOX / Protoporphyrinogen oxidase · IHC design guide
Design Immunohistochemistry for PPOX
Use catalog antibody A01856 at 1:50–1:200 for paraffin IHC (datasheet). Kidney tubules provide a high-staining reference, but interpret the observed cytoplasmic and nuclear pattern cautiously because HPA rates its tissue IHC reliability uncertain (HPA tissue IHC).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
PPOX Immunohistochemistry Experimental Design Guide
Expected localisation, validated protocols, controls and antibodies — the at-a-glance facts below, then the full design guide.
Must know before staining
| Expected localisation | IHC: cytoplasm and nucleus (HPA tissue IHC) | |
| Staining pattern | Most tissues show cytoplasmic and nuclear staining (HPA tissue IHC) | |
| Antigen retrieval | Citrate pH 6.0 HIER, 95–98 °C, 20 min (rule: cytoplasmic / membrane antigen) | |
| Positive control | Adrenal gland+4 more · see all | |
| Negative control | Appendix+4 more · see all |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Keep fixation consistent across paraffin sections. (standard IHC practice; not target-specific) | |
| Caveat | Staining and RNA expression show low consistency (HPA tissue IHC) | |
| Regulation | No expression regulation reported (UniProt) | |
| Isoform / epitope | No annotated isoforms or processing (UniProt) |
Section 1
Recommended PPOX IHC & IF Protocols
The catalog antibody’s IHC-P protocol is accompanied by a published PPOX staining protocol for glioma tissue (PMC9157484).
| Sample | Paraffin-embedded human colon carcinoma tissue; fixative not specified (datasheet A01856) |
| Fixation | Image fixative and duration unreported (datasheet A01856); verify before use. |
| Sectioning | 4–5 µm sections on charged slides (standard) |
| Deparaffinisation | Xylene, graded ethanol series to water (standard) |
| Antigen retrieval | Heat-induced epitope retrieval in citrate buffer, pH 6.0, 20 min at 95–98 °C (standard rule: cytoplasmic / membrane antigen) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% normal serum of the secondary host, 30 min, room temperature (standard) |
| Primary antibody | Rabbit anti-PPOX, 1:50-1:200 (datasheet A01856) |
| Primary incubation | Overnight at 4 °C (standard) |
| Detection | HRP-polymer secondary, DAB chromogen 5–10 min (standard) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | PPOX-positive staining in glandular cells of adrenal gland (HPA tissue IHC: High). HPA tissue profile: Cytoplasmic and nuclear expression in most tissues. No signal in the no-primary control. |
💡Decision noteStart with citrate pH 6.0 retrieval at 95–98 °C for 20 min (page retrieval rule); the glioma study used high-pH heat retrieval (PMC9157484).
Section 2
What Is the Expected PPOX Staining Pattern?
PPOX is an inner mitochondrial membrane protein with no annotated transmembrane segment (UniProt P50336 topology). In paraffin IHC, expect cytoplasmic staining in glandular cells and kidney tubules reported as high by HPA (HPA tissue IHC). HPA also reports nuclear staining in most tissues, but rates its tissue IHC reliability Uncertain because staining and RNA expression have low consistency (HPA tissue IHC).
| Granular cytoplasmic signal in kidney tubule cells or adrenal glandular cells, with limited background. | This is a plausible positive IHC result: HPA reports High staining in both cell types (HPA tissue IHC). Mitochondrial localization supports cytoplasmic signal, but chromogenic IHC alone does not establish that each stained granule is a mitochondrion (UniProt P50336 subcellular location; HPA subcellular ICC-IF). |
| Predominantly nuclear signal with little cytoplasmic signal. | Review this as a compartment mismatch against PPOX's mitochondrial location (UniProt P50336 subcellular location). HPA describes cytoplasmic and nuclear tissue staining, but rates that IHC profile Uncertain; nuclear staining alone cannot confirm PPOX or establish an artefact (HPA tissue IHC). |
| Strong signal in alveolar cells or cardiomyocytes. | These cells are reported Not detected by HPA tissue IHC, so investigate cross-reactivity or endogenous detection activity (HPA tissue IHC; general IHC practice). Treat the discrepancy as a flag, not proof of nonspecific staining: UniProt reports PPOX expression in lung and heart (UniProt P50336 tissue specificity). |
| Diffuse color across tissue, stroma, or a reagent-only control. | A widespread signal that does not resolve to cells is difficult to interpret as PPOX staining (general IHC practice). Background can arise from detection chemistry or insufficient blocking and washing; compare a primary-antibody omission control before assigning cellular staining (general IHC practice). |
| No signal in kidney tubule cells despite a readable counterstain. | Kidney tubules are a useful expected-positive comparator because HPA reports High staining there (HPA tissue IHC). An absent signal calls for a run and control review; it cannot by itself establish absent PPOX because the HPA tissue IHC profile has Uncertain reliability (HPA tissue IHC). |
💡Expected PPOX appearanceCall a result provisionally positive when cytoplasmic staining is clear in HPA High glandular cells or kidney tubules with restrained background; diffuse tissue-wide color or isolated strong nuclear staining needs investigation (HPA tissue IHC; UniProt P50336 subcellular location; general IHC practice).
| Cell type and tissue | Compare like cells: HPA reports High staining in kidney tubules and several glandular epithelia, but Not detected in appendix glandular cells, cardiomyocytes, and alveolar cells (HPA tissue IHC). These are observed IHC patterns, not universal positive or negative controls (HPA tissue IHC reliability: Uncertain). |
| Subcellular interpretation | UniProt places PPOX at the inner mitochondrial membrane without an annotated transmembrane segment; HPA ICC-IF approves mitochondria as the main location and also reports vesicles and cytosol (UniProt P50336 topology; HPA subcellular ICC-IF). The ICC-IF localization informs interpretation but does not validate chromogenic IHC staining (HPA tissue IHC: Uncertain). |
| Antibody evidence | The listed antibody HPA030123 is Uncertain for IHC and Approved for ICC (HPA antibodies). Its ICC status does not upgrade its IHC validation; assess staining alongside cell-type patterns and controls (HPA antibodies; HPA tissue IHC; general IHC practice). |
| Processing and variants | UniProt annotates a single chain spanning residues 1–477, with no signal peptide, propeptide, glycosylation sites, or isoforms in this record (UniProt P50336 processing). These annotations provide no basis to predict a tissue-specific cleavage pattern or a fixation-dependent staining change (UniProt P50336 processing). |
| Situation | Likely cause | Next action |
|---|---|---|
| Kidney tubules fail to stain in the test run. | A missed positive may reflect a run or reagent problem; HPA reports kidney tubules as High, with Uncertain overall IHC reliability (HPA tissue IHC; general IHC practice). | Check a known working tissue control, primary-antibody dilution, retrieval conditions, detection reagents, and counterstain in the same run; avoid calling the sample PPOX-negative from this result alone (general IHC practice; HPA tissue IHC reliability: Uncertain). |
| Nuclei dominate the signal. | A nucleus-dominant pattern conflicts with the mitochondrial assignment, although HPA's uncertain tissue IHC profile includes nuclear staining (UniProt P50336 subcellular location; HPA tissue IHC). | Compare cytoplasmic staining in HPA high cell types and check omission and detection controls; report the nuclear pattern separately instead of using it alone to call PPOX positive (HPA tissue IHC; general IHC practice). |
| Color appears in alveolar cells or cardiomyocytes. | HPA reports these cells as Not detected in IHC, while UniProt reports PPOX expression in lung and heart; the evidence does not resolve that difference (HPA tissue IHC; UniProt P50336 tissue specificity). | Check cellular boundaries and an appropriate primary-antibody omission control for endogenous detection activity; describe the observed staining without treating the HPA negative as definitive (general IHC practice; HPA tissue IHC reliability: Uncertain). |
| Background obscures cytoplasmic staining. | Nonspecific binding or detection activity can create diffuse chromogenic color (general IHC practice). | Inspect omission controls, blocking, washes, and detection conditions; judge cell-specific signal only after background is low enough to distinguish stained cells (general IHC practice). |
| A whole section looks uniformly positive. | HPA describes staining in most tissues, but its IHC profile is Uncertain; uniform color alone cannot establish PPOX expression in every cell (HPA tissue IHC). | Score named cell populations separately, compare HPA reported high and not-detected cells where present, and inspect controls for background before assigning positivity (HPA tissue IHC; general IHC practice). |
| IHC appears nuclear while ICC-IF appears mitochondrial. | HPA approves mitochondrial ICC-IF localization but rates the tissue IHC profile Uncertain; the assays have different validation statuses (HPA subcellular ICC-IF; HPA tissue IHC). | Keep the IHC and ICC-IF observations distinct, verify IHC controls, and avoid using the ICC result as proof that the nuclear IHC signal identifies PPOX (HPA antibodies; general IHC practice). |
Experiment evidence
IHC & IF images showing PPOX staining
A01856 · IHCImmunohistochemistry of paraffin-embedded human colon carcinoma using PPOX antibody at dilution of 1:100 .Perform microwave antigen retrieva
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000143224-PPOX/tissue/cerebral+cortex#imid_8729380
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000143224-PPOX/tissue/colon#imid_8729290
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000143224-PPOX/tissue/liver#imid_8729291
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000143224-PPOX/tissue/kidney#imid_8729308
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA030123; green = PPOX, blue = nucleus, red = microtubules.
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA030123; green = PPOX, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for PPOX IHC & IF
🧪Run adrenal gland first and expect glandular cells to stain (HPA: High in adrenal gland glandular cells); use appendix glandular cells as the negative tissue (HPA: Not detected in appendix glandular cells). Compare staining with non-glandular areas on the adrenal slide as an internal background reference, while recognizing that HPA does not designate an adrenal cell type as PPOX-negative (HPA: adrenal gland glandular cells High).
Positive control tissue: Adrenal gland (Glandular cells, HPA High)
Negative control tissue: Appendix (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show PPOX in A-431, HeLa, U2OS, with annotated localisation: Mitochondria (approved) (HPA subcellular).
Technical controls: Include a no-primary, secondary-only control; a concentration-matched isotype control matching the primary antibody’s host species and clonality; and PPOX knockout material or a validated immunizing-peptide block as a biological specificity control (standard IHC practice). For chromogenic detection in adrenal tissue, quench endogenous peroxidase and use the no-primary slide to assess background, including pigment (standard IHC practice).
⚠️Feasibility: A PPOX-specific fixation window or fixation effect is unreported in the supplied evidence, and the selected A01856 paraffin-section caption does not report a fixative (A01856 tissue-IHC caption). That caption uses microwave retrieval in 10 mM PBS at pH 7.2 and a 1:100 antibody dilution, but does not establish whether retrieval is essential (A01856 tissue-IHC caption). Frozen-section performance and whether IF is easier are unreported; HPA shows mitochondrial ICC-IF localization, while pigment and endogenous peroxidase should be checked when interpreting adrenal chromogenic staining (HPA: subcellular PPOX; standard IHC practice).
HPA tissue IHC evidence for PPOX
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Uncertain — Low consistency between antibody staining and RNA expression data. Pending external verification.). 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 |
|---|---|---|---|---|
| Adrenal gland | Glandular cells | High | Protein (IHC) | HPA → |
| Breast | Glandular cells | High | Protein (IHC) | HPA → |
| Bronchus | Respiratory epithelial cells | High | Protein (IHC) | HPA → |
| Endometrium | Cells in endometrial stroma | Low | Protein (IHC) | HPA → |
| Fallopian tube | Glandular cells | High | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Appendix | Glandular cells | Not detected | Protein (IHC) | HPA → |
| Cerebellum | Cells in granular layer | Not detected | Protein (IHC) | HPA → |
| Epididymis | Glandular cells | Not detected | Protein (IHC) | HPA → |
| Heart muscle | Cardiomyocytes | Not detected | Protein (IHC) | HPA → |
| Lung | Alveolar cells | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced PPOX IHC Tips
Troubleshoot PPOX staining in paraffin sections using mitochondrial localisation, the reported tissue pattern, and controls that distinguish signal from background.
How should I retrieve PPOX antigen when paraffin-section staining is weak?
Start with citrate buffer at pH 6.0, heated to 95–98 °C for 20 minutes (page retrieval rule: cytoplasmic / membrane antigen). Allow sections to cool in buffer, then compare staining with a no-primary control processed through the same chromogenic workflow (standard IHC practice). The selected A01856 image instead used microwave retrieval in 10 mM PBS, pH 7.2, on paraffin-embedded human colon carcinoma at 1:100; use that as a fallback if the page condition gives weak staining (A01856 caption). Compare both conditions on adjacent sections and check whether stronger signal retains a plausible intracellular pattern rather than increasing diffuse background (UniProt P50336 localisation; standard IHC practice).
Could fixation explain weak or patchy PPOX staining?
Target-specific PPOX sensitivity to fixation is unknown from the supplied evidence; the A01856 paraffin-section caption does not state a fixative (A01856 caption). Record the fixative, fixation duration, section thickness, and time in storage for each specimen before comparing staining across runs (standard IHC practice). If fixation varies, stain adjacent sections with the same retrieval, antibody dilution, detection reagents, and development time so those variables do not obscure the comparison (standard IHC practice). Examine preserved tissue away from damaged edges, and use a no-primary control to separate tissue background from antibody-dependent signal (standard IHC practice). Do not assign a fixation mechanism to PPOX from its mitochondrial location or unannotated modifications alone (UniProt P50336 record).
What staining pattern is plausible for PPOX in tissue sections?
Expect predominantly intracellular staining compatible with mitochondria, because PPOX is assigned to the mitochondrial inner membrane and HPA reports mitochondria as its main approved subcellular location (UniProt P50336 localisation; HPA subcellular). The record annotates no transmembrane segment, so the inner-membrane assignment does not establish which face contains an antibody epitope (UniProt P50336 topology). HPA also reports vesicular and cytosolic locations in cell imaging, while its tissue IHC profile describes cytoplasmic and nuclear staining with uncertain reliability (HPA subcellular; HPA tissue IHC). Judge punctate or granular cytoplasmic chromogen against cell morphology and controls; investigate dominant nuclear-only or surface-only staining before calling it PPOX (standard IHC practice; UniProt P50336 localisation).
How can epitope uncertainty affect interpretation of PPOX IHC?
The supplied record lists a single 1–477 chain and no annotated isoforms, domains, glycosylation sites, or modified residues (UniProt P50336 record). It also lists no transmembrane segment despite the inner-membrane localisation, so do not infer an epitope's membrane-facing side from topology alone (UniProt P50336 topology and localisation). Check the antibody's stated immunogen or epitope information, if available, before comparing antibodies or adjusting permeabilisation; no epitope position is supplied here (standard IHC practice; supplied antibody evidence). For an ambiguous pattern, compare serial sections and a no-primary control, then seek independent antibody or orthogonal evidence before assigning a nuclear or membrane-surface signal to a PPOX variant (standard IHC practice; HPA tissue IHC: uncertain).
How should I follow up an ambiguous PPOX IHC pattern by IF?
Use IF as a separate follow-up assay: HPA reports mitochondrial localisation in cell imaging, but that observation does not specify a validated IF protocol for the IHC antibody (HPA subcellular; supplied antibody evidence). Multiplex PPOX with a tubular epithelial marker when examining kidney sections, since HPA reports high staining in kidney tubule cells (HPA tissue IHC: High in kidney tubules; standard IF practice). Choose a far-red fluorophore and assess unstained tissue in each channel to manage autofluorescence (standard IF practice). Optimise permeabilisation for access to the tested epitope while preserving mitochondrial structure; its membrane-facing side is not established by the supplied topology (UniProt P50336 topology; standard IF practice).
How can I reduce diffuse chromogenic background without losing PPOX signal?
First compare a no-primary section with the stained section to identify detection-reagent or tissue background, using matched exposure to each processing step (standard IHC practice). For peroxidase-based chromogenic detection, block endogenous peroxidase before applying antibody and inspect the control after DAB development; these are general workflow steps, not PPOX-specific evidence (standard IHC practice). Increase washing, optimise the blocking step, and titrate the primary around the documented 1:100 A01856 image condition rather than assuming that image dilution is optimal for every specimen (A01856 caption; standard IHC practice). Accept a reduction in diffuse colour only if interpretable intracellular staining persists in preserved cells (UniProt P50336 localisation; standard IHC practice).
What is a defensible way to quantify PPOX IHC across samples? ⚠ ANSWER MARKED FOR VERIFICATION
Define the tissue compartment and eligible cell population before scoring, then apply the same threshold, imaging conditions, and DAB development time to all sections (standard IHC practice). For cell-level assessment, report the percentage of positive cells and an H-score calculated from the percentages at intensity grades 0–3; for spatial assessment, report positive-cell density per mm² of viable tissue (standard IHC practice). Normalise cell counts to the number of eligible cells, or density to analysed viable area, and exclude folds, edges, and necrosis by a prespecified rule (standard IHC practice). Report no-primary background and avoid treating HPA's uncertain tissue profile as a quantitative reference standard (HPA tissue IHC: Uncertain; standard IHC practice).
When should an apparent PPOX-positive area be considered artefactual?
Give greatest weight to intracellular staining in intact cells that exceeds the matched no-primary control and is compatible with PPOX's mitochondrial assignment (UniProt P50336 localisation; standard IHC practice). Check the cell population: HPA reports high staining in kidney tubule cells but no detected staining in lung alveolar cells, although its tissue IHC reliability is uncertain (HPA tissue IHC: High in kidney tubules; Not detected in lung alveolar cells; Uncertain). Treat isolated section-edge staining, necrotic deposits, and colour reproduced by the no-primary control as possible processing or endogenous-enzyme artefacts (standard IHC practice). Investigate strong nuclear-only staining with independent evidence before attributing it to PPOX, because the reported nuclear tissue pattern has low consistency with RNA expression (HPA tissue IHC: Uncertain; UniProt P50336 localisation).
Boster reagents
Best PPOX / Protoporphyrinogen oxidase IHC Antibodies
One anti-PPOX antibody has real IHC data from paraffin-embedded human colon carcinoma (A01856 image caption); the catalog lists human and mouse reactivity (A01856 catalog). No IF data are supplied (A01856 catalog).
Real IHC data
Anti-Protoporphyrinogen oxidase PPOX Antibody
Cat # A01856
A01856 is listed for IHC and has an image of paraffin-embedded human colon carcinoma stained at 1:100 after microwave retrieval in 10 mM PBS, pH 7.2 (A01856 image caption). The catalog lists human and mouse reactivity for A01856, but provides no mouse IHC image or IF image (A01856 catalog).
Which to pick: For paraffin-section IHC, choose A01856: its own image caption documents staining of human colon carcinoma, and the catalog lists an IHC dilution of 1:50–1:200 (A01856 image caption; A01856 catalog). The caption does not report the fixative (A01856 image caption). For IF/ICC, no SKU has listed validation; for mouse samples, A01856 lists mouse reactivity, although its supplied IHC image is human (A01856 catalog; A01856 image caption).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry P50336 (PPOX_HUMAN, Protoporphyrinogen oxidase).
- Human Protein Atlas. PPOX tissue IHC expression (reliability: Uncertain).
- Human Protein Atlas. PPOX subcellular location (ICC-IF): Mainly localized to the mitochondria. In addition localized to vesicles and cytosol..
- Human Protein Atlas. PPOX antibody validation summary (1 antibodies).
- Heme Biosynthesis Factors and 5-ALA Induced Fluorescence: Analysis of mRNA and Protein Expression in Fluorescing and Non-fluorescing Gliomas. Frontiers in medicine 2022 — PMC9157484.
- The orexin system as a pharmacological target in inflammation: peripheral mechanisms and safety implications. Frontiers in pharmacology 2026 — PMC13478096.
- Comprehensive bioinformatics and experimental analysis of PPOX reveals its carcinogenic effect in clear cell renal cell carcinoma. Translational andrology and urology 2026 — PMC13264790.
- PubMed PMID:7713909 — UniProt-cited evidence.
- PubMed PMID:8771201 — UniProt-cited evidence.
- PubMed PMID:8806618 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for PPOX (Protoporphyrinogen oxidase). Expected localisation IHC: cytoplasm and nucleus (HPA tissue IHC). Antigen retrieval: Citrate pH 6.0 HIER, 95–98 °C, 20 min (rule: cytoplasmic / membrane antigen). Validated IHC antibody: A01856 at 1:50-1:200 (the product's own IHC validation image is shown). Controls (HPA): positive Adrenal gland (Glandular cells); negative Appendix. IHC workflow; specimen preparation unspecified. Protocol steps: 1. Sample: Paraffin-embedded human colon carcinoma tissue; fixative not specified (datasheet A01856); 2. Fixation: Image fixative and duration unreported (datasheet A01856); verify before use.; 3. Sectioning: 4–5 µm sections on charged slides (standard); 4. Deparaffinisation: Xylene, graded ethanol series to water (standard); 5. Antigen retrieval: Heat-induced epitope retrieval in citrate buffer, pH 6.0 , 20 min at 95–98 °C…; 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% normal serum of the secondary host, 30 min , room temperature (standard); 8. Primary antibody: Rabbit anti-PPOX, 1:50-1:200 (datasheet A01856); 9. Primary incubation: Overnight at 4 °C (standard). Watch for: Fixation: Keep fixation consistent across paraffin sections. (standard IHC practice; not target-specific); Caveat: Staining and RNA expression show low consistency (HPA tissue IHC); Isoform / epitope: No annotated isoforms or processing (UniProt); Regulation: No expression regulation reported (UniProt). Evidence: UniProt P50336, HPA tissue IHC · Uncertain, HPA ICC-IF · Mainly localized to the mitochondria. In addition localized to…, Datasheet A01856, PMC9157484. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/PPOX/immunohistochemistry-ihc-guide.