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CYP2U1 / Cytochrome P450 2U1 · IHC design guide
Design Immunohistochemistry for CYP2U1
Plan chromogenic CYP2U1 IHC in paraffin sections using lung macrophages as a candidate positive control (HPA tissue IHC). Assess cytoplasmic and membranous staining while accounting for the uncertain tissue-IHC reliability (HPA tissue IHC).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
CYP2U1 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 | Cytoplasmic and membranous tissue staining (HPA tissue IHC) | |
| Staining pattern | Several tissues show cytoplasmic and membranous staining (HPA tissue IHC) | |
| Antigen retrieval | Citrate pH 6.0 HIER, 95–98 °C, 20 min (rule: cytoplasmic / membrane antigen) | |
| Positive control | Appendix+4 more · see all | |
| Negative control | Hippocampus+1 more · see all |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Keep paraffin-section fixation consistent across samples (standard IHC practice; not target-specific) | |
| Caveat | Staining and RNA expression show low consistency (HPA tissue IHC) | |
| Regulation | Stimulus-linked regulation is not established (UniProt) | |
| Isoform / epitope | 2 isoforms; epitope differences are unspecified (UniProt) |
Section 1
Recommended CYP2U1 IHC & IF Protocols
Compare the catalog antibody’s IHC-P protocol with the published breast cancer tissue microarray protocol (PMC7419690).
| Sample | Tissue sections; selected-image fixative not specified (standard IHC workflow) |
| Fixation | Image fixative and duration unreported (datasheet PA2022); 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-CYP2U1, 0.5-1μg/ml (datasheet PA2022) |
| 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 | CYP2U1-positive staining in lymphoid tissue of appendix (HPA tissue IHC: High). HPA tissue profile: Cytoplasmic and membranous expression in several tissues. No signal in the no-primary control. |
💡Decision noteStart with citrate pH 6.0 retrieval at 95–98 °C for 20 min (page antigen retrieval rule); the published protocol used pH 8.0 (PMC7419690).
Section 2
What Is the Expected CYP2U1 Staining Pattern?
CYP2U1 is assigned to the endoplasmic reticulum, microsome and mitochondrial inner membranes, with 5 predicted transmembrane segments (UniProt Q7Z449 topology). In paraffin-section IHC, expect cytoplasmic and membranous staining in selected cells, including lung macrophages, breast myoepithelial cells and splenic white-pulp cells (HPA tissue IHC). Treat this as a provisional pattern: HPA rates tissue IHC reliability Uncertain because staining and RNA expression show low consistency (HPA tissue IHC).
| Distinct cytoplasmic or membranous stain appears in lung macrophages or breast myoepithelial cells. | This matches reported High staining in those cells (HPA tissue IHC) and is compatible with membrane-associated CYP2U1 (UniProt Q7Z449 topology). Assess the named cells against nearby cells and the negative control; a brown area alone does not identify its source (general IHC practice). |
| Staining is predominantly nuclear, with little cytoplasmic or membranous signal. | That differs from the reported tissue IHC pattern (HPA tissue IHC). Check whether counterstain, precipitate or nonspecific antibody signal explains it (general IHC practice). An uncertain nucleoplasmic location in ICC-IF does not establish nuclear staining as the expected paraffin-section result (HPA subcellular ICC-IF). |
| Strong stain appears in an unexpected cell population, such as hippocampal glia or liver cholangiocytes. | Those particular populations were Not detected in HPA tissue IHC (HPA tissue IHC). Consider cross-reactivity or endogenous chromogen-generating activity, then compare controls and cell morphology (general IHC practice). Their HPA result is a comparison point, not proof that every such cell must remain negative. |
| Weak, diffuse brown colour covers many tissue compartments and obscures cell boundaries. | A broad haze cannot reliably be scored as the reported cell-selective cytoplasmic and membranous pattern (HPA tissue IHC). Review the negative control, blocking, washing and chromogen development for nonspecific background (general IHC practice); do not convert diffuse colour into a CYP2U1-positive call. |
| No stain appears in a section containing a reported-high cell population. | First confirm that the relevant cells are present: HPA reports High staining in lung macrophages, splenic white-pulp cells and several other specified populations (HPA tissue IHC). Absent signal may reflect the assay or sample; the Uncertain HPA reliability prevents treating one negative section as decisive biological absence. |
💡Expected CYP2U1 appearanceCall a result provisionally positive when a reported cell population shows distinct cytoplasmic or membranous staining, potentially High in lung macrophages or splenic white-pulp cells (HPA tissue IHC); diffuse haze or isolated strong nuclear colour is a suspect positive pattern (HPA tissue IHC; general IHC practice).
| Membrane topology | CYP2U1 has 5 predicted transmembrane segments and assigned ER, microsome and mitochondrial inner-membrane locations (UniProt Q7Z449 topology). These support a membrane-associated interpretation, but chromogenic tissue IHC alone cannot distinguish those organelles (general IHC practice). |
| Tissue and cell selection | HPA reports High stain in appendix lymphoid tissue, gallbladder and small-intestinal glandular cells, smooth muscle cells, and splenic white-pulp cells, among others (HPA tissue IHC). Choose a comparator by its specified cell population; staining intensity does not apply uniformly to every cell in that tissue. |
| Evidence reliability | HPA calls the tissue IHC profile Uncertain because antibody staining and RNA expression have low consistency; both listed tissue-IHC antibodies are individually marked Uncertain (HPA tissue IHC; HPA antibodies). Treat intensity and negative-cell expectations as provisional, especially when a specimen disagrees. |
| Isoforms and antibody recognition | UniProt lists 2 CYP2U1 isoforms (UniProt Q7Z449). The supplied HPA records do not specify which isoform an IHC antibody recognizes (HPA antibodies). An apparent difference between samples therefore cannot be assigned to isoform expression from staining alone. |
| IF/ICC Q&A | Q: Should IF/ICC show the same compartments? A: HPA reports mainly Golgi localization, with approved vesicular and uncertain nucleoplasmic localization in ICC-IF (HPA subcellular ICC-IF). That separate assay does not resolve the tissue-IHC pattern or override UniProt membrane assignments (HPA tissue IHC; UniProt Q7Z449). |
| Situation | Likely cause | Next action |
|---|---|---|
| A reported-high population stains weakly or remains blank. | The relevant cells may be absent from the section, or the IHC workflow may have lost sensitivity (HPA tissue IHC; general IHC practice). | Confirm cell identity on the counterstained section, then check the IHC-validated antibody's documented retrieval, dilution and detection conditions; compare a control section in the same run (general IHC practice). |
| Strong signal appears in HPA not-detected cell populations. | Cross-reactivity or endogenous chromogen-generating activity is possible; HPA lists hippocampal glia and liver cholangiocytes as Not detected (HPA tissue IHC; general IHC practice). | Inspect a negative control and the cellular distribution; check endogenous-enzyme blocking when using enzyme-based detection before scoring those cells positive (general IHC practice). |
| Brown haze covers the whole section. | Nonspecific binding, inadequate washing or excessive chromogen development can obscure the reported cytoplasmic and membranous pattern (general IHC practice; HPA tissue IHC). | Review blocking, washing and development time against a negative control, then score only distinct cellular signal above background (general IHC practice). |
| The main apparent signal is in nuclei. | The pattern conflicts with HPA tissue IHC; the separate ICC-IF nucleoplasmic annotation is Uncertain (HPA tissue IHC; HPA subcellular ICC-IF). | Check counterstain and precipitate, compare the negative control, and withhold a CYP2U1-positive call until a cellular pattern can be distinguished (general IHC practice). |
| Two antibodies give different tissue patterns. | The listed tissue-IHC antibodies are each rated Uncertain, and HPA reports low staining–RNA consistency (HPA antibodies; HPA tissue IHC). | Record antibody identity and the stained cell populations separately; use concordant controls and avoid treating either pattern alone as definitive (general IHC practice). |
| A whole tissue seems positive, but the expected cells are hard to locate. | HPA assigns staining levels to named populations, such as lung macrophages, rather than to every cell in the organ (HPA tissue IHC). | Identify the named cells using morphology and counterstain, then score their compartment and intensity separately from surrounding cells (general IHC practice). |
Experiment evidence
IHC & IF images showing CYP2U1 staining
PA2022 · IHCAnti-CYP2U1 antibody, PA2022, IHC(P) IHC(P): Human Intestinal Cancer Tissue
PA2022 · IFAnti-CYP2U1 antibody, PA2022, ICC ICC: HELA Cell
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000155016-CYP2U1/tissue/cerebral+cortex#imid_13026683
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000155016-CYP2U1/tissue/colon#imid_13026609
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000155016-CYP2U1/tissue/liver#imid_13026594
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000155016-CYP2U1/tissue/kidney#imid_13026595
![HPA ICC-IF BJ [Human fibroblast] — CYP2U1 (HPA064827)](https://images.proteinatlas.org/64827/1527_B2_1_blue_red_green.jpg)
HPA · ICC-IF BJ [Human fibroblast]Human Protein Atlas immunofluorescence, BJ [Human fibroblast], antibody HPA064827; green = CYP2U1, blue = nucleus, red = microtubules.
![HPA ICC-IF BJ [Human fibroblast] — CYP2U1 (HPA064827)](https://images.proteinatlas.org/64827/1527_B2_2_blue_red_green.jpg)
HPA · ICC-IF BJ [Human fibroblast]Human Protein Atlas immunofluorescence, BJ [Human fibroblast], antibody HPA064827; green = CYP2U1, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for CYP2U1 IHC & IF
🧪Run lung first and assess macrophages, where CYP2U1 staining is High (HPA: High in lung macrophages). Use liver cholangiocytes as the biological negative (HPA: Not detected in liver cholangiocytes); on the lung slide, compare macrophages with nearby non-macrophage cells as an internal background reference, without assuming those cells are CYP2U1-negative (HPA: High is assigned to macrophages).
Positive control tissue: Appendix (Lymphoid tissue, HPA High)
Negative control tissue: Hippocampus (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show CYP2U1 in BJ [Human fibroblast], SK-MEL-30, U2OS, with annotated localisation: Golgi apparatus (approved) (HPA subcellular).
Technical controls: Include a no-primary, secondary-only control and an isotype control matched to the primary antibody’s host species and clonality where applicable; use CYP2U1 knockout material or antigen-peptide competition if available as a target-specific control (standard IHC practice). For chromogenic lung IHC, block endogenous peroxidase and check macrophage pigment against the no-primary control; for IF, assess lung autofluorescence (standard IHC/IF practice).
⚠️Feasibility: A target-specific fixation window or fixation effect is unreported, and the selected PA2022 paraffin-section caption does not state a fixative (PA2022 IHC(P) caption). Retrieval dependency is unreported in the supplied evidence, so optimise retrieval empirically for paraffin sections (standard IHC practice). HPA has ICC-IF images in BJ, SK-MEL-30 and U2OS cells, but the supplied evidence does not establish whether frozen sections or IF are easier for this antibody; lung macrophage pigment and autofluorescence need control checks (HPA: ICC-IF image cell lines; standard IHC/IF practice).
HPA tissue IHC evidence for CYP2U1
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Uncertain — Low consistency between antibody staining and RNA expression data.). 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 |
|---|---|---|---|---|
| Appendix | Lymphoid tissue | High | Protein (IHC) | HPA → |
| Breast | Myoepithelial cells | High | Protein (IHC) | HPA → |
| Gallbladder | Glandular cells | High | Protein (IHC) | HPA → |
| Lung | Macrophages | High | Protein (IHC) | HPA → |
| Skin | Fibroblasts | Medium | Protein (IHC) | HPA → |
Section 3
Advanced CYP2U1 IHC Tips
Troubleshoot CYP2U1 staining in paraffin sections by checking retrieval, compartment pattern, tissue controls, and scoring before interpreting chromogenic signal.
How should I adjust retrieval when CYP2U1 staining is weak or uneven?
Use citrate pH 6.0 heat-induced epitope retrieval at 95–98 °C for 20 min (page retrieval specification). If staining is weak, compare sections processed with the specified retrieval against sections given a modestly longer heating time, while keeping cooling and detection conditions matched (standard IHC practice). Check that staining remains associated with cells and has a plausible cytoplasmic or membranous pattern (HPA tissue IHC: cytoplasmic and membranous expression); diffuse staining across tissue edges suggests a processing artefact (standard IHC practice). Document the retrieval condition for each section because a change in signal alone cannot establish antibody specificity, particularly when tissue staining and RNA show low consistency (HPA tissue IHC: Uncertain reliability).
Could fixation explain weak CYP2U1 staining in my paraffin sections?
Target-specific fixation sensitivity is unknown from the supplied evidence; the PA2022 tissue-IHC caption identifies human intestinal cancer tissue but does not state its fixative (PA2022 tissue-IHC caption). Record the actual fixative, fixation duration, tissue thickness, and delay before fixation for each specimen so that preanalytic differences can be assessed (standard IHC practice). Compare sections from similarly processed blocks using the same retrieval and detection settings, then look for consistent staining in intact cells rather than preferential staining at cut edges (standard IHC practice). Do not attribute a weak result to CYP2U1 membrane topology or lack of annotated glycosylation, because neither establishes fixation sensitivity (UniProt Q7Z449: topology and glycosylation annotations).
Which compartments should contain credible CYP2U1 signal in chromogenic IHC?
Evaluate staining in relation to cell boundaries and cytoplasm: tissue IHC reports cytoplasmic and membranous expression (HPA tissue IHC: profile). UniProt places CYP2U1 at the endoplasmic reticulum membrane, microsome membrane, and mitochondrial inner membrane (UniProt Q7Z449: subcellular locations), so fine intracellular staining can be biologically plausible without resolving those organelles by chromogenic microscopy (standard IHC practice). A separate cell-imaging dataset reports mainly Golgi localization and additional vesicular localization, with nucleoplasmic localization marked uncertain (HPA subcellular: locations); it should not dictate a single paraffin-section pattern. Review staining against tissue morphology and a no-primary control before assigning diffuse nuclear or extracellular color to CYP2U1 (standard IHC practice).
How do CYP2U1 isoforms and membrane topology affect epitope troubleshooting?
CYP2U1 has 2 annotated isoforms and 5 predicted transmembrane segments (UniProt Q7Z449: isoforms and topology). The supplied evidence does not identify the catalog antibody's epitope, so isoform recognition and whether its epitope faces an accessible side of a membrane remain unresolved (supplied antibody evidence: epitope not stated). Request the immunogen or epitope sequence and compare it with both isoform sequences before claiming isoform-specific staining (standard antibody-validation practice). When staining differs across blocks, first standardize retrieval and detection, then test specificity with an independent antibody recognizing a distinct region or an appropriate loss-of-target control if available (standard IHC validation practice).
How can IF help resolve an ambiguous CYP2U1 IHC pattern?
Use IF as a separate localization check and multiplex CYP2U1 with a marker for the cell population being evaluated; lung macrophages and appendix lymphoid tissue provide documented staining contexts (HPA tissue IHC: High in macrophages; High in lymphoid tissue). Choose a fluorophore channel with low autofluorescence in that specimen and include unstained and single-color controls before interpreting overlap (standard IF practice). Permeabilisation should be chosen after establishing the antibody epitope's membrane-facing side; CYP2U1 has 5 transmembrane segments, but its antibody epitope is unspecified (UniProt Q7Z449: topology; supplied antibody evidence: epitope not stated). Compare intracellular patterns cautiously because cell imaging reports Golgi and vesicular localization, whereas tissue IHC reports cytoplasmic and membranous staining (HPA subcellular: locations; HPA tissue IHC: profile).
What should I check when CYP2U1 DAB staining is widespread?
Run a no-primary control through the same peroxidase block, secondary reagent, and DAB development to identify detection-system or endogenous-enzyme color (standard chromogenic IHC practice). Compare control and test sections at the same development time, and inspect folds, drying artefacts, tissue edges, and necrotic areas before scoring cells (standard IHC practice). If diffuse color persists only with primary antibody, titrate the antibody and strengthen appropriate protein blocking while holding retrieval and DAB time constant (standard IHC practice). Require a coherent cytoplasmic or membranous cellular pattern before calling CYP2U1 positive, and interpret broad tissue staining conservatively because reported antibody staining has low consistency with RNA expression (HPA tissue IHC: profile and Uncertain reliability).
How should I score CYP2U1 across specimens with different cell compositions? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and tissue compartment before scoring, since high staining is reported in lung macrophages and spleen white-pulp cells (HPA tissue IHC: positive-cell entries). For chromogenic sections, report the percentage of positive target cells and staining intensity, or calculate an H-score from intensity-weighted percentages using one threshold across the comparison (standard IHC scoring practice). Normalize counts to the number of evaluable target cells; for spatial burden, report positive-cell density per mm² of viable, annotated tissue (standard quantitative pathology practice). Exclude folds, necrosis, and edge artefacts, and report controls and batch conditions alongside scores because tissue-IHC reliability is uncertain (standard IHC practice; HPA tissue IHC: Uncertain reliability).
When is CYP2U1 staining convincing rather than an artefact?
A convincing call requires reproducible cellular staining with a plausible cytoplasmic or membranous pattern and an appropriately quiet no-primary control (HPA tissue IHC: profile; standard IHC validation practice). Check the stained cell type: lung macrophages show high reported staining, while hippocampal glial cells and liver cholangiocytes are reported as not detected (HPA tissue IHC: positive and negative entries). Treat isolated extracellular deposits, tissue-edge accentuation, necrotic staining, and residual endogenous peroxidase color as possible artefacts until controls resolve them (standard chromogenic IHC practice). Even a plausible pattern does not prove molecular specificity or CYP2U1 activity; the tissue-IHC assessment is uncertain because staining has low consistency with RNA expression (HPA tissue IHC: reliability description).
Boster reagents
Best CYP2U1 / Cytochrome P450 2U1 IHC Antibodies
PA2022 has IHC data from human intestinal cancer tissue and ICC data from HELA cells (PA2022 image captions); reported reactivity is Human only (catalog: reactivity).
Real IHC data
Anti-Cytochrome P450 2U1 CYP2U1 Antibody ®
Cat # PA2022
PA2022 was tested for IHC and ICC in Human samples (catalog: applications, reactivity). Its images show paraffin-section IHC in human intestinal cancer tissue and ICC in HELA cells (PA2022 image captions).
Which to pick: For tissue IHC, choose PA2022: its IHC(P) image shows human intestinal cancer tissue, while the fixative is unreported (PA2022 IHC(P) image caption). For IF/ICC, PA2022 has an ICC image in HELA cells and a listed IF dilution of 0.5–1 μg/ml; the caption does not specify fluorescence detection (PA2022 ICC image caption; catalog: IF dilution). No SKU here has reported non-human reactivity for cross-species use (catalog: reactivity).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry Q7Z449 (CP2U1_HUMAN, Cytochrome P450 2U1).
- Human Protein Atlas. CYP2U1 tissue IHC expression (reliability: Uncertain).
- Human Protein Atlas. CYP2U1 subcellular location (ICC-IF): Mainly localized to the Golgi apparatus. In addition localized to the nucleoplasm and vesicles..
- Human Protein Atlas. CYP2U1 antibody validation summary (3 antibodies).
- Cytochrome P450 2U1 Is a Novel Independent Prognostic Biomarker in Breast Cancer Patients. Frontiers in oncology 2020 — PMC7419690.
- Mechanism of Tetrandrine in Ameliorating Hypoxic Pulmonary Hypertension Vascular Remodeling through Transcriptomics and Metabolomics. Current drug metabolism 2025 — PMC12728530.
- Differential Expression of Prostaglandin I2 Synthase Associated with Arachidonic Acid Pathway in the Oral Squamous Cell Carcinoma. Journal of oncology 2018 — PMC6250001.
- PubMed PMID:14660610 — UniProt-cited evidence.
- PubMed PMID:15489334 — UniProt-cited evidence.
- PubMed PMID:14975754 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for CYP2U1 (Cytochrome P450 2U1). Expected localisation Cytoplasmic and membranous tissue staining (HPA tissue IHC). Antigen retrieval: Citrate pH 6.0 HIER, 95–98 °C, 20 min (rule: cytoplasmic / membrane antigen). Validated IHC antibody: PA2022 at 0.5-1μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Appendix (Lymphoid tissue); negative Hippocampus. IHC workflow; specimen preparation unspecified. Protocol steps: 1. Sample: Tissue sections; selected-image fixative not specified (standard IHC workflow); 2. Fixation: Image fixative and duration unreported (datasheet PA2022); 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-CYP2U1, 0.5-1μg/ml (datasheet PA2022); 9. Primary incubation: Overnight at 4 °C (standard). Watch for: Fixation: Keep paraffin-section fixation consistent across samples (standard IHC practice; not target-specific); Caveat: Staining and RNA expression show low consistency (HPA tissue IHC); Isoform / epitope: 2 isoforms; epitope differences are unspecified (UniProt); Regulation: Stimulus-linked regulation is not established (UniProt). Evidence: UniProt Q7Z449, HPA tissue IHC · Uncertain, HPA ICC-IF · Mainly localized to the Golgi apparatus. In addition localized to…, Datasheet PA2022, PMC7419690. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/CYP2U1/immunohistochemistry-ihc-guide.