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ENDOU / Uridylate-specific endoribonuclease · IHC design guide
Design Immunohistochemistry for ENDOU
Plan ENDOU chromogenic IHC in paraffin sections using placenta as a positive tissue and the catalog antibody’s IHC-P conditions (HPA tissue IHC; datasheet A07350-1). Compare cytoplasmic staining in trophoblasts and squamous epithelia, accounting for ENDOU secretion when interpreting cell-level patterns (HPA tissue IHC; UniProt).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
ENDOU 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 tissue staining; secreted protein (HPA tissue IHC; UniProt) | |
| Staining pattern | Cytoplasmic staining in trophoblasts and squamous epithelia (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet A07350-1) | |
| Positive control | Cervix+4 more · see all | |
| Negative control | Adipose tissue+4 more · see all |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Matched tissue-IHC evidence does not establish the fixation claim. Validate the specimen-specific method before use. (selected-SKU IHC image A07350-1) | |
| Caveat | Secretion may separate protein staining from its source cells (UniProt; HPA tissue IHC) | |
| Regulation | Tissue-dependent expression (HPA tissue IHC) | |
| Isoform / epitope | 3 isoforms; signal peptide is cleaved; epitope map unknown (UniProt) |
Section 1
Recommended ENDOU IHC & IF Protocols
The catalog antibody specifies EDTA pH 8.0 retrieval (datasheet: A07350-1). Two published ENDOU IHC protocols cover cervical tissue arrays and placental sections (PMC8548783; PMC8611368).
| Sample | Paraffin-embedded human lung cancer tissue; fixative not specified (datasheet A07350-1) |
| Fixation | Image fixative and duration unreported (datasheet A07350-1); verify before use. |
| Sectioning | 4–5 µm sections on charged slides (standard) |
| Deparaffinisation | Xylene, graded ethanol series to water (standard) |
| Antigen retrieval | Heat retrieval: EDTA pH 8.0 (datasheet A07350-1); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet A07350-1) |
| Primary antibody | Rabbit anti-ENDOU, 2-5 μg/ml (datasheet A07350-1) |
| Primary incubation | Overnight at 4 °C (datasheet A07350-1) |
| Detection | HRP-conjugated secondary, DAB chromogen (datasheet A07350-1) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | ENDOU-positive staining in squamous epithelial cells of cervix (HPA tissue IHC: High). HPA tissue profile: Cytoplasmic expression in placenta and squamous epithelia. No signal in the no-primary control. |
💡Decision noteStart with EDTA pH 8.0 heat retrieval (datasheet: A07350-1); the published protocols offer Tris-EDTA pH 7.8 and pH 9.0 conditions to compare (PMC8548783; PMC8611368).
Section 2
What Is the Expected ENDOU Staining Pattern?
In paraffin section IHC, expect cytoplasmic ENDOU staining in placental trophoblastic cells and squamous epithelia, particularly cervical and oral mucosal squamous cells (HPA: tissue IHC profile; HPA: High in these cells). ENDOU is a secreted protein with a signal peptide and no transmembrane segment (UniProt P21128: subcellular location and topology). HPA rates the tissue pattern Enhanced but reports only medium agreement between staining and RNA expression (HPA: reliability).
| Clear cytoplasmic staining in placental trophoblastic cells or cervical or oral squamous epithelial cells, with little staining in adjacent cells. | This fits the reported cell and compartment pattern; HPA scores these cells High (HPA: tissue IHC). Assess the named cells rather than averaging the whole section, because the reported result is cell specific (HPA: tissue IHC). |
| Predominantly nuclear or sharply membrane confined staining, without the expected cytoplasmic pattern. | That distribution conflicts with HPA's cytoplasmic profile and UniProt's secreted, nontransmembrane annotation (HPA: tissue IHC; UniProt P21128: location and topology). Check staining specificity and section interpretation before assigning it to ENDOU (standard IHC practice). |
| Strong staining in a cell type HPA lists as Not detected, while the expected positive cells are unstained. | For example, adipocytes in adipose tissue are listed as Not detected (HPA: tissue IHC). Cross reactivity or endogenous detection activity is possible; compare antibody omitted and detection controls before calling this ENDOU (standard IHC practice). |
| A uniform haze extends across multiple tissue compartments, obscuring individual cell boundaries. | This is difficult to score against a cell resolved cytoplasmic pattern (HPA: tissue IHC). Review blocking, antibody concentration, washing and chromogen development with an antibody omitted control (standard IHC practice). Secreted ENDOU can complicate tissue location, so extracellular signal alone is not decisive (UniProt P21128: Secreted; HPA: reliability note). |
| No signal in placental trophoblastic cells or cervical squamous epithelial cells. | Both are High staining comparators in HPA tissue IHC (HPA: tissue IHC). Check section quality, retrieval, antibody and detection reagents, then compare with a positive section run in the same batch (standard IHC practice); absence alone does not identify the failed step. |
💡Expected ENDOU appearanceA convincing positive shows clear cytoplasmic staining in High scoring placental trophoblastic or cervical or oral squamous epithelial cells; dominant nuclear staining or uniform slide wide haze warrants a specificity check (HPA: tissue IHC; standard IHC practice).
| Cell resolved tissue pattern | HPA reports High staining in placental trophoblastic cells and cervical, oral mucosal and skin granular layer cells; esophageal and vaginal squamous cells are Medium (HPA: tissue IHC). Choose a High group for a positive comparator and score its specified cells (standard IHC practice). |
| Secretion and tissue location | ENDOU is secreted and has no transmembrane segment (UniProt P21128: location and topology). HPA cautions that protein and RNA tissue locations may differ for secreted proteins, contributing to its medium staining to RNA agreement (HPA: reliability description). Avoid using RNA distribution alone to reject a protein stain. |
| Maturation and antibody epitope | UniProt annotates a signal peptide at residues 1–18 and a mature chain at 19–410 (UniProt P21128: processing). The supplied antibody record gives no epitope position, so these coordinates cannot predict staining strength or retrieval needs. |
| Isoforms and validation | UniProt lists 3 isoforms without supplied tissue specific staining assignments (UniProt P21128: isoforms). Two rabbit polyclonal antibodies, HPA012388 and HPA067448, have Enhanced IHC validation (HPA: antibodies); that supports the reported pattern but does not identify which isoform either stain detects. |
| IF/ICC Q&A: What pattern is established? | HPA calls ENDOU Secreted but lists no main ICC/IF location or cell line images, and neither supplied antibody has an ICC validation entry (HPA: subcellular; HPA: antibodies). This record cannot establish an IF/ICC cell pattern or a protocol. |
| Situation | Likely cause | Next action |
|---|---|---|
| Placental trophoblasts are blank. | A failed antibody or detection step is possible; trophoblastic cells are High in HPA tissue IHC (HPA: tissue IHC). | Run a known positive section with the same reagents and review retrieval, antibody dilution and chromogen steps (standard IHC practice). No ENDOU specific retrieval condition is supplied. |
| Only esophageal or vaginal squamous cells appear weak. | Both groups are Medium, while cervical and oral mucosal squamous cells are High in HPA tissue IHC (HPA: tissue IHC). | Compare the same run with a High staining tissue and score the correct epithelial cells (HPA: tissue IHC; standard IHC practice). Do not diagnose reagent failure from a Medium group alone. |
| Adipocytes or respiratory epithelial cells stain strongly. | HPA lists these cells as Not detected in adipose tissue and bronchus, respectively (HPA: tissue IHC); nonspecific antibody or detection signal is possible (standard IHC practice). | Check an antibody omitted control and compare the suspect staining with a positive tissue in the same run (standard IHC practice). |
| Nuclei dominate the stain. | A nuclear dominant result conflicts with HPA's cytoplasmic tissue profile (HPA: tissue IHC); its cause is unresolved from appearance alone. | Inspect counterstain and antibody omitted control, then repeat with a validated IHC antibody if needed (standard IHC practice; HPA: antibody IHC validation). |
| Diffuse color obscures cell boundaries. | Background from antibody concentration, blocking, washing or detection is possible (standard IHC practice); secreted ENDOU also complicates location based interpretation (UniProt P21128: Secreted; HPA: reliability note). | Review controls, titrate the antibody and adjust washing or detection conditions while retaining a High staining comparator (standard IHC practice; HPA: tissue IHC). |
| Protein staining and tissue RNA results disagree. | HPA reports medium consistency and explicitly expects RNA and protein locations to differ for a secreted protein (HPA: reliability description; UniProt P21128: Secreted). | Interpret cell level IHC with tissue controls and the reported protein pattern; do not use RNA location alone as proof of staining failure (HPA: tissue IHC and reliability note). |
Experiment evidence
IHC & IF images showing ENDOU staining
A07350-1 · IHCIHC analysis of PP11/ENDOU using anti-PP11/ENDOU antibody (A07350-1). PP11/ENDOU was detected in a paraffin-embedded section of human lung c
A07350-1 · IHCIHC analysis of PP11/ENDOU using anti-PP11/ENDOU antibody (A07350-1). PP11/ENDOU was detected in a paraffin-embedded section of human placen
A07350-1 · IFIF analysis of PP11/ENDOU using anti-PP11/ENDOU antibody (A07350-1). PP11/ENDOU was detected in an immunocytochemical section of Caco-2 cell
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000111405-ENDOU/tissue/cerebral+cortex#imid_3209496
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000111405-ENDOU/tissue/colon#imid_3209438
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000111405-ENDOU/tissue/liver#imid_3209431
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000111405-ENDOU/tissue/kidney#imid_3209424
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for ENDOU IHC & IF
🧪Run placenta first and score trophoblastic cells, which show High ENDOU staining (HPA: placenta, trophoblastic cells). Use adipose tissue adipocytes as the negative comparator (HPA: adipose tissue, adipocytes, Not detected); on the placenta slide, treat non-trophoblastic cells without signal above background as an internal staining reference, without assuming every such cell is ENDOU-negative.
Positive control tissue: Cervix (Squamous epithelial cells, HPA High)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA carries no ICC-IF cell line for ENDOU; derive a cell-line control from the positive tissue's cell type (Squamous epithelial cells) and confirm it by RNA or western blot first.
Technical controls: Include no-primary (secondary-only) and rabbit immunoglobulin isotype controls matched to the primary antibody’s class and clonality where known (selected-SKU caption: rabbit primary antibody). Use an ENDOU knockout specimen, if available, as a biological negative; quench endogenous peroxidase and check blood-rich placental areas for residual DAB background (IHC practice; HPA: placenta, trophoblastic cells).
⚠️Feasibility: A target-specific fixation window or fixation effect is unreported, and the selected-SKU paraffin-section caption does not state the fixative (selected-SKU caption: fixative not stated). The caption uses heat retrieval in EDTA at pH 8.0, which provides a starting condition but does not establish that retrieval is required (selected-SKU caption: heat-mediated EDTA retrieval). Frozen sections and IF have no supplied matched validation and cannot be judged easier; because ENDOU is secreted, assess extracellular signal cautiously, especially around placental trophoblasts (HPA: no ICC-IF image cell lines; UniProt P21128: Secreted; HPA: placenta, trophoblastic cells).
HPA tissue IHC evidence for ENDOU
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Enhanced — Medium consistency between antibody staining and RNA expression data. Secreted protein, tissue location of RNA and protein is expected to differ.). 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 |
|---|---|---|---|---|
| Cervix | Squamous epithelial cells | High | Protein (IHC) | HPA → |
| Oral mucosa | Squamous epithelial cells | High | Protein (IHC) | HPA → |
| Placenta | Trophoblastic cells | High | Protein (IHC) | HPA → |
| Skin | Cells in granular layer | High | Protein (IHC) | HPA → |
| Esophagus | Squamous epithelial cells | Medium | Protein (IHC) | HPA → |
Undetected expression · recommended 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 → |
| Bone marrow | Hematopoietic cells | Not detected | Protein (IHC) | HPA → |
| Breast | Adipocytes | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced ENDOU IHC Tips
Troubleshoot ENDOU staining in paraffin sections by checking retrieval, cell type, localisation, and controls before comparing chromogenic IHC with IF.
How should I retrieve ENDOU in paraffin sections when staining is weak?
Start with heat-mediated retrieval in EDTA at pH 8.0 for ENDOU paraffin sections (datasheet A07350-1). The selected image used this retrieval before overnight incubation with 2 μg/ml primary antibody at 4°C, so repeat those documented conditions before changing retrieval chemistry (datasheet A07350-1). If staining remains weak, compare a second retrieval condition on adjacent sections while holding antibody concentration, detection, and development constant (standard IHC practice). Judge the result in trophoblastic cells or squamous epithelium, and reject conditions that increase diffuse staining without improving cell-associated signal (HPA tissue IHC; standard IHC practice).
Can fixation explain variable ENDOU staining across paraffin blocks?
The selected paraffin-section caption does not state a fixative, and no target-specific fixation sensitivity is supplied for ENDOU (datasheet A07350-1). Record each block’s fixative and processing history, then compare similarly processed sections before attributing intensity differences to biology (standard IHC practice). If signal varies, test the documented EDTA pH 8.0 retrieval and 2 μg/ml antibody conditions on matched controls, with the same chromogen development time (datasheet A07350-1; standard IHC practice). Neither the reported tissue pattern nor ENDOU’s secreted topology establishes how a particular fixative affects its epitope, so describe any fixation effect as unresolved until directly tested (HPA tissue IHC; UniProt P21128 topology; standard IHC practice).
What ENDOU staining pattern should I expect in a tissue section?
Evaluate cell-associated cytoplasmic staining first: that is the reported tissue IHC pattern in placenta and squamous epithelia (HPA tissue IHC). ENDOU has a 1–18 signal peptide, lacks a transmembrane segment, and is annotated as secreted, so extracellular staining can complicate assignment to the producing cell (UniProt P21128 topology). Compare trophoblastic cells and squamous epithelial cells with nearby tissue structures, preserving morphology with a counterstain and identical DAB development (HPA tissue IHC; standard IHC practice). If staining appears exclusively nuclear or only along cut edges, review controls and section quality before calling it ENDOU localisation (HPA tissue IHC; UniProt P21128 subcellular location; standard IHC practice).
Could isoform choice or epitope processing change my IHC result?
ENDOU has 3 annotated isoforms, but the supplied antibody caption does not map its epitope or establish isoform recognition (UniProt P21128 isoforms; datasheet A07350-1). Its signal peptide spans residues 1–18, while the annotated mature chain spans 19–410; an antibody’s actual binding region must be checked before interpreting processing-related loss of staining (UniProt P21128 processing; standard IHC practice). No glycosylation sites or modified residues are listed in the supplied record, which does not establish whether fixation or retrieval preserves this antibody’s epitope (UniProt P21128 PTMs; standard IHC practice). When cases disagree, compare a documented positive tissue control under identical retrieval and detection conditions before assigning the difference to an isoform (HPA tissue IHC; standard IHC practice).
How can IF help assess an uncertain chromogenic ENDOU pattern?
Use IF as a separate localisation check alongside the paraffin-section IHC result; the supplied HPA subcellular record lists no ICC/IF images or established intracellular location (HPA subcellular). Multiplex ENDOU with a marker identifying the expected trophoblastic or squamous epithelial cell population, and confirm overlap at the cell level rather than relying on tissue-wide fluorescence (HPA tissue IHC; standard IF practice). Choose fluorophores after inspecting unstained tissue for autofluorescence, and include single-stain controls when channels overlap (standard IF practice). For an intracellular epitope, optimise permeabilisation; for a surface-accessible epitope, test without it, because the antibody epitope is unspecified and ENDOU is secreted without a transmembrane segment (datasheet A07350-1; UniProt P21128 topology; standard IF practice).
What should I check when ENDOU DAB staining looks diffuse?
First compare no-primary and secondary-only controls, then inspect whether brown signal follows tissue edges, damaged areas, or the expected cells (standard IHC practice; HPA tissue IHC). The selected image used 10% goat serum blocking, a peroxidase-conjugated secondary, and DAB, making blocking consistency and endogenous peroxidase suppression practical checks in this chromogenic workflow (datasheet A07350-1; standard IHC practice). Keep DAB development comparable across control and test sections, and retitrate the documented 2 μg/ml primary condition if background obscures morphology (datasheet A07350-1; standard IHC practice). Because ENDOU is secreted, diffuse extracellular colour alone cannot identify its cellular source; require credible cell-associated staining and appropriate controls (UniProt P21128 subcellular location; HPA tissue IHC; standard IHC practice).
How should I score ENDOU staining across tissue samples? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and compartment before scoring, using cytoplasmic staining in trophoblastic or squamous epithelial cells where those populations are present (HPA tissue IHC). Report the percentage of positive target cells and an intensity-weighted H-score, with fixed thresholds and the same DAB development conditions across sections (standard IHC practice). If counting discrete positive cells, report density per mm² of viable, evaluable tissue and exclude folds, damaged edges, and necrotic areas (standard IHC practice). Normalise to the number of evaluable target cells or their viable tissue area, and retain a reference positive section in each run to detect staining drift (HPA tissue IHC; standard IHC practice).
When is a positive ENDOU IHC result biologically credible?
A credible result shows reproducible, cell-associated cytoplasmic staining in a plausible population, such as placental trophoblastic cells or squamous epithelial cells (HPA tissue IHC). Compare it with a control population reported as undetected, such as adipocytes in adipose tissue, while recognising that the antibody and processing still require run-level controls (HPA tissue IHC; standard IHC practice). Predominantly nuclear colour, staining restricted to section edges or necrosis, and signal persisting without primary antibody warrant investigation before a positive call (UniProt P21128 subcellular location; HPA tissue IHC; standard IHC practice). Because ENDOU is secreted, extracellular DAB deposits should be interpreted with adjacent cell morphology and controls, not assigned automatically to the nearest cell (UniProt P21128 subcellular location; standard IHC practice).
Boster reagents
Best ENDOU / Uridylate-specific endoribonuclease IHC Antibodies
The IHC-validated anti-ENDOU antibody has IHC data from human paraffin-embedded lung cancer and placenta sections, plus IF data from Caco-2 cells (A07350-1 image captions).
Real IHC data
Anti-PP11/ENDOU Antibody ®
Cat # A07350-1
A07350-1 has IHC images from human paraffin-embedded lung cancer and placenta sections (A07350-1 IHC image captions). The same SKU lists human reactivity and IF/ICC applications, with an IF image from Caco-2 cells (A07350-1 catalog and IF image caption).
Which to pick: Choose A07350-1 for human paraffin-section IHC; its own captions show EDTA retrieval at pH 8.0 and primary antibody at 2 μg/ml, but do not report the fixative (A07350-1 IHC image captions). For IF/ICC, A07350-1 lists 5 μg/ml and has a Caco-2 IF image (A07350-1 catalog and IF image caption). No cross-species choice is documented because the catalog lists human reactivity only; the clone field is unreported (A07350-1 catalog).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry P21128 (ENDOU_HUMAN, Uridylate-specific endoribonuclease).
- Human Protein Atlas. ENDOU tissue IHC expression (reliability: Enhanced).
- Human Protein Atlas. ENDOU subcellular location (ICC-IF): Secreted.
- Human Protein Atlas. ENDOU antibody validation summary (2 antibodies).
- Integrative meta-analysis of gene expression profiles identifies FEN1 and ENDOU as potential diagnostic biomarkers for cervical squamous cell carcinoma. Oncology letters 2021 — PMC8548783.
- Upregulation of ENDOU in cytotrophoblasts from placenta complicated with preeclampsia and fetal growth restriction. Journal of clinical biochemistry and nutrition 2021 — PMC8611368.
- PubMed PMID:2350438 — UniProt-cited evidence.
- PubMed PMID:14702039 — UniProt-cited evidence.
- PubMed PMID:16541075 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for ENDOU (Uridylate-specific endoribonuclease). Expected localisation Cytoplasmic tissue staining; secreted protein (HPA tissue IHC; UniProt). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet A07350-1). Validated IHC antibody: A07350-1 at 2-5 μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Cervix (Squamous epithelial cells); negative Adipose tissue. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human lung cancer tissue; fixative not specified (datasheet A07350-1); 2. Fixation: Image fixative and duration unreported (datasheet A07350-1); 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 retrieval: EDTA pH 8.0 (datasheet A07350-1); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet A07350-1); 8. Primary antibody: Rabbit anti-ENDOU, 2-5 μg/ml (datasheet A07350-1); 9. Primary incubation: Overnight at 4 °C (datasheet A07350-1). Watch for: Fixation: Matched tissue-IHC evidence does not establish the fixation claim. Validate the specimen-specific method before use. (selected-SKU IHC image A07350-1); Caveat: Secretion may separate protein staining from its source cells (UniProt; HPA tissue IHC); Isoform / epitope: 3 isoforms ; signal peptide is cleaved; epitope map unknown (UniProt); Regulation: Tissue-dependent expression (HPA tissue IHC). Evidence: UniProt P21128, HPA tissue IHC · Enhanced, HPA ICC-IF · Secreted, Datasheet A07350-1, PMC8548783, PMC8611368. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/ENDOU/immunohistochemistry-ihc-guide.