This website uses cookies to ensure you get the best experience on our website.
- Table of Contents
CHTOP / Chromatin target of PRMT1 protein · IHC design guide
Design Immunohistochemistry for CHTOP
Plan chromogenic CHTOP IHC on paraffin sections using the catalog antibody at 2–5 µg/mL (datasheet A07770-2). Assess nuclear staining across tissues (HPA tissue IHC) with matched controls (standard IHC practice).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
CHTOP 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 | Nuclear in most tissues (HPA tissue IHC) | |
| Staining pattern | Nuclear staining across most tissues (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet A07770-2) | |
| Positive control | Adipose tissue+4 more · see all | |
| Negative control | None in HPA (detected in all 45 tissues); use no-primary + isotype controls |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Keep fixation consistent across sections (standard IHC practice; not target-specific) | |
| Caveat | Hematopoietic cells may show strong staining (HPA tissue IHC) | |
| Regulation | No abundance regulator specified (UniProt) | |
| Isoform / epitope | 3 isoforms; epitope coverage is unknown (UniProt) |
Section 1
Recommended CHTOP IHC & IF Protocols
The catalog antibody’s IHC-P protocol (datasheet: A07770-2) appears alongside 2 published paraffin-section CHTOP protocols (PMC6465198; PMC6660285).
| Sample | Paraffin-embedded human breast cancer tissue; fixative not specified (datasheet A07770-2) |
| Fixation | Image fixative and duration unreported (datasheet A07770-2); 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 A07770-2); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet A07770-2) |
| Primary antibody | Rabbit anti-CHTOP, 2 μg/ml (datasheet A07770-2) |
| Primary incubation | Overnight at 4 °C (datasheet A07770-2) |
| Detection | HRP-conjugated secondary, DAB chromogen (datasheet A07770-2) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | CHTOP-positive staining in adipocytes of adipose tissue (HPA tissue IHC: High). HPA tissue profile: Nuclear expression in most tissues. No signal in the no-primary control. |
💡Decision noteStart with heat-mediated EDTA pH 8.0 retrieval for the catalog antibody (datasheet: A07770-2). Sodium citrate retrieval is a published alternative (PMC6465198).
Section 2
What Is the Expected CHTOP Staining Pattern?
CHTOP should stain nuclei across many cell types in paraffin sections (HPA: nuclear expression in most tissues; low tissue specificity). High staining is reported in adipocytes, hematopoietic cells, respiratory epithelial cells and glial cells, among others (HPA: tissue IHC). Nuclear speckles and surrounding perispeckles refine the expected location (HPA: ICC-IF; UniProt Q9Y3Y2). The HPA tissue profile is Approved, with medium consistency between staining and RNA data (HPA: tissue IHC). CHTOP has no transmembrane segment (UniProt Q9Y3Y2 topology).
| Nuclear chromogen in adipocytes, bone marrow hematopoietic cells or bronchial respiratory epithelial cells, with little competing background. | This fits reported high staining in those cells and the broad nuclear tissue profile (HPA: tissue IHC). Judge nuclear staining against adjacent morphology and a counterstain; intensity alone cannot establish antibody specificity (standard IHC practice). |
| Predominantly cytoplasmic, membranous or extracellular deposit, without convincing nuclear staining. | That distribution conflicts with the reported nuclear pattern and absence of a transmembrane segment (HPA: tissue IHC; UniProt Q9Y3Y2 topology). Consider nonspecific binding or detection artefact; a single discordant section does not identify its cause (standard IHC practice). |
| Strong staining confined to an unexpected cell population, especially with weak nuclei in a reported high staining population. | Check cell identity and morphology first: CHTOP has low tissue specificity, so an unlisted cell type is not automatically negative (HPA: tissue IHC). If the distribution remains discordant, assess cross-reactivity or endogenous detection activity using appropriate controls (standard IHC practice). |
| Diffuse chromogen across nuclei, cytoplasm and tissue spaces, obscuring cell boundaries. | The expected readout is nuclear, so widespread diffuse deposit cannot be scored confidently as CHTOP (HPA: tissue IHC). Background may arise from nonspecific antibody binding, detection reagents or incomplete washing; compare the negative control and reagent controls (standard IHC practice). |
| No nuclear signal in an adequately preserved section of bone marrow hematopoietic cells or adrenal glandular cells. | Both are reported as high staining populations (HPA: tissue IHC). First verify that these cells are present, then check antibody and detection controls. A negative result can reflect assay failure or specimen variation; HPA reports medium staining and RNA consistency (HPA: tissue IHC). |
💡Expected CHTOP appearanceCall a section positive when identifiable cells show convincing nuclear chromogen, particularly in HPA high staining populations; predominantly cytoplasmic or extracellular color is discordant (HPA: tissue IHC; UniProt Q9Y3Y2 topology).
| Tissue and cell choice | Use a reported high staining population as an interpretable positive reference, such as adipocytes in adipose tissue or hematopoietic cells in bone marrow (HPA: tissue IHC). HPA lists no negative tissue here; do not designate one from this record (HPA: supplied tissue IHC profile). |
| Subnuclear distribution | CHTOP is reported in nucleus, nucleolus and nucleoplasm, with localization around speckles in perispeckles (UniProt Q9Y3Y2). HPA ICC-IF supports nuclear speckles (HPA: subcellular). Chromogenic IHC may show an overall nuclear pattern without resolving these structures (standard IHC practice). |
| Antibody evidence | HPA028647 has Approved IHC status, while HPA030540 has Supported ICC status in the supplied antibody record (HPA: antibody validation). Treat these as application-specific evidence; the supplied record does not establish equivalent performance for both methods (HPA: antibody validation). |
| Isoforms and modifications | UniProt lists three isoforms and modified residues, including phosphorylation sites (UniProt Q9Y3Y2). Without an epitope map or assay data, their effects on staining cannot be assigned; interpret discordance through controls rather than presuming isoform loss or modification-dependent detection (standard IHC practice). |
| Topology and processing | No transmembrane segment, signal peptide or propeptide is reported; the annotated chain spans residues 2–248 (UniProt Q9Y3Y2 topology and processing). An extracellular or membranous IHC pattern therefore warrants review, but these annotations alone do not identify the artefact (UniProt Q9Y3Y2; standard IHC practice). |
| IF/ICC: what pattern should I expect? | Expect nuclear speckles in ICC-IF (HPA: supported subcellular localization). HPA lists A-431, U-251MG, U2OS and NIH 3T3 among imaged cell lines (HPA: subcellular). This observation answers localization only; use the separate IF/ICC guide for that application. |
| Situation | Likely cause | Next action |
|---|---|---|
| No staining in a reported high staining population. | The target cells may be absent from the examined area, or an assay step may have failed; HPA reports high staining in several specified populations (HPA: tissue IHC; standard IHC practice). | Confirm target-cell morphology and section integrity, then check the IHC-validated antibody, detection reagents and positive control. Review retrieval conditions empirically as general IHC optimization; no CHTOP-specific retrieval condition is supplied (standard IHC practice). |
| Strong cytoplasmic color with weak or absent nuclear color. | The compartment is discordant with CHTOP’s nuclear distribution (HPA: tissue IHC; UniProt Q9Y3Y2). Nonspecific binding or excessive detection signal is possible (standard IHC practice). | Compare negative controls, reduce antibody or detection strength if background is high, and score only clearly resolved nuclei. Do not treat cytoplasmic color alone as a positive CHTOP result (standard IHC practice; HPA: tissue IHC). |
| Color appears in an unexpected cell type. | Low tissue specificity means the cell type may still express CHTOP; cross-reactivity or endogenous detection activity is another possibility (HPA: tissue IHC; standard IHC practice). | Identify the cells by morphology, compare nuclear localization with a reported high staining population, and use detection-only controls where relevant. Avoid calling an unlisted cell type negative solely because it is absent from this HPA excerpt (HPA: tissue IHC; standard IHC practice). |
| Diffuse haze prevents nuclear scoring. | Background can reflect nonspecific binding, insufficient washing or detection-reagent activity (standard IHC practice). HPA’s expected pattern is nuclear, so the haze limits interpretation (HPA: tissue IHC). | Inspect the negative control, improve washing or blocking as indicated by the control, and titrate the IHC antibody or detection system. Reassess whether nuclear boundaries remain visible before scoring (standard IHC practice). |
| A section gives a different pattern from another specimen. | HPA reports nuclear expression in most tissues but only medium consistency between antibody staining and RNA data; tissue composition and assay conditions can also differ (HPA: tissue IHC; standard IHC practice). | Compare equivalent cell populations, section quality and controls before interpreting biological variation. Record the compartment and cell type alongside intensity; avoid inferring target-specific fixation sensitivity because none is supplied here (HPA: tissue IHC; standard IHC practice). |
| Punctate IF/ICC signal seems inconsistent with smoother chromogenic IHC nuclei. | HPA supports nuclear speckles in ICC-IF, while its tissue IHC summary describes nuclear expression (HPA: subcellular; HPA: tissue IHC). The two observations have different spatial detail (standard microscopy practice). | Interpret each image within its application: confirm speckle-associated nuclear signal for IF/ICC and identifiable nuclear chromogen for IHC. Refer to the separate IF/ICC guide for that assay (HPA: subcellular; HPA: tissue IHC). |
Experiment evidence
IHC & IF images showing CHTOP staining
A07770-2 · IHCIHC analysis of C1orf77/FOP/CHTOP using anti-C1orf77/FOP/CHTOP antibody (A07770-2). C1orf77/FOP/CHTOP was detected in a paraffin-embedded se
A07770-2 · IHCIHC analysis of C1orf77/FOP/CHTOP using anti-C1orf77/FOP/CHTOP antibody (A07770-2). C1orf77/FOP/CHTOP was detected in a paraffin-embedded se
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000160679-CHTOP/tissue/cerebral+cortex#imid_7164136
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000160679-CHTOP/tissue/colon#imid_7164054
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000160679-CHTOP/tissue/liver#imid_7164063
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000160679-CHTOP/tissue/kidney#imid_7164056
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA030540; green = CHTOP, blue = nucleus, red = microtubules.
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA030540; green = CHTOP, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for CHTOP IHC & IF
🧪Run adipose tissue first and score nuclear staining in adipocytes (HPA: High in adipocytes; UniProt: nuclear localization). HPA detects CHTOP in all 45 scored tissues, so there is no supported negative tissue; no-primary and isotype controls carry the negative, while cells without nuclear signal on the positive slide, if present, are background references rather than validated CHTOP-negative cells (HPA: no negative tissue rows).
Positive control tissue: Adipose tissue (Adipocytes, HPA High)
Negative control tissue: None in HPA: CHTOP is detected in all 45 scored tissues. Use a no-primary (secondary-only) and an isotype control instead.
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show CHTOP in A-431, U-251MG, U2OS, NIH 3T3, with annotated localisation: Nuclear speckles (supported) (HPA subcellular).
Technical controls: Include a no-primary, secondary-only control and a concentration-matched rabbit isotype control alongside a CHTOP knockout sample or a validated peptide-block control (caption: rabbit primary antibody; standard IHC practice). Check for endogenous peroxidase signal in the adipose section before interpreting DAB staining (caption: HRP/DAB detection; standard IHC practice).
⚠️Feasibility: A target-specific fixation window or fixation effect is unreported, and the selected A07770-2 paraffin-section caption does not state the fixative (selected-SKU tissue-IHC caption). Heat retrieval in EDTA at pH 8.0 is documented for that IHC example, but whether retrieval is required is unreported (selected-SKU tissue-IHC caption). Frozen sections are not established as easier; ICC-IF images support a nuclear-speckle readout, while adipocyte nuclei can be sparse and peripheral, so score nuclei rather than empty lipid spaces (HPA subcellular: nuclear speckles; HPA: High in adipocytes; standard histology).
HPA tissue IHC evidence for CHTOP
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Approved — Medium 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 |
|---|---|---|---|---|
| Adipose tissue | Adipocytes | High | Protein (IHC) | HPA → |
| Adrenal gland | Glandular cells | High | Protein (IHC) | HPA → |
| Appendix | Lymphoid tissue | High | Protein (IHC) | HPA → |
| Bone marrow | Hematopoietic cells | High | Protein (IHC) | HPA → |
| Breast | Adipocytes | High | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| None in HPA: CHTOP is detected in all 45 scored tissues. Use a no-primary (secondary-only) and an isotype control instead. | ||||
Section 3
Advanced CHTOP IHC Tips
Troubleshoot chromogenic CHTOP IHC by checking nuclear localisation, retrieval conditions, tissue controls and the limits of the antibody evidence.
How should I retrieve CHTOP in paraffin sections with the catalog antibody?
Start with heat-mediated antigen retrieval in EDTA at pH 8.0 for catalog antibody A07770-2 (datasheet A07770-2). The documented paraffin-section image used that retrieval before 2 μg/ml primary antibody overnight at 4°C, but reports no retrieval duration (datasheet A07770-2). If nuclear signal is weak, vary heating time in a small section series while holding antibody concentration and detection constant, then compare nuclear signal with tissue damage (standard IHC practice). Include a no-primary control for each retrieval condition because stronger heating can also increase nonspecific chromogenic signal (standard IHC practice). Score nuclei in intact tissue rather than judging retrieval from total DAB darkness (standard IHC practice; HPA tissue IHC: nuclear expression).
Could fixation explain weak or uneven CHTOP staining?
The selected paraffin-section caption does not state a fixative, so CHTOP sensitivity to a particular fixative or fixation duration is unknown for this antibody (datasheet A07770-2). Record the fixative, time before fixation and fixation duration for every block; compare blocks processed alike before attributing differences to biology (standard IHC practice). Evaluate nuclear staining in well-preserved areas, because poor morphology can make compartment assignment and cell counting unreliable (standard IHC practice; HPA tissue IHC: nuclear expression). If staining varies across a section, inspect whether the variation follows tissue edges or damaged regions, then compare an independently processed section (standard IHC practice). Do not infer fixation sensitivity from CHTOP localisation or modifications (UniProt Q9Y3Y2; datasheet A07770-2: fixative unreported).
What CHTOP staining pattern should I expect in tissue sections?
Expect predominantly nuclear staining across many tissues, and assess intensity within identified cell types rather than across the whole section (HPA tissue IHC: nuclear expression in most tissues). CHTOP is annotated in nucleoplasm, nucleolus and nuclear speckles, including perispeckle regions; those fine compartments may not be separable by chromogenic tissue IHC (UniProt Q9Y3Y2; standard IHC practice). Its lack of a transmembrane segment does not make a crisp membrane outline an expected target pattern (UniProt Q9Y3Y2 topology). Use a nuclear counterstain to check that DAB signal overlaps intact nuclei, and investigate predominantly cytoplasmic or membrane staining with control sections (standard IHC practice; HPA tissue IHC: nuclear expression).
Can isoforms or modifications change what this antibody detects?
CHTOP has 3 annotated isoforms and several modified residues, including phosphorylation sites at positions 33, 40, 49 and 64 (UniProt Q9Y3Y2). The supplied caption gives antibody concentration and staining conditions but no epitope sequence, so isoform coverage and modification sensitivity cannot be assigned to A07770-2 (datasheet A07770-2). When comparing specimens, keep retrieval and antibody conditions constant and report nuclear staining as staining by this antibody, rather than as abundance of a particular isoform (standard IHC practice; UniProt Q9Y3Y2). If a specific isoform is essential to the experiment, establish epitope coverage from antibody documentation or orthogonal evidence before interpreting differential staining (standard IHC practice).
How can I follow up a chromogenic CHTOP result with IF?
Use the IHC result to select cells for an IF follow-up, then multiplex CHTOP with a validated marker for the expected cell type and a nuclear counterstain (standard IF practice; HPA tissue IHC: nuclear expression). Choose fluorophores after examining unstained tissue in each channel, placing the critical nuclear signal where tissue autofluorescence is lowest (standard IF practice). Permeabilise sufficiently for antibody access to the intranuclear epitope, and compare mild conditions because excessive extraction can reduce retained nuclear signal (standard IF practice; UniProt Q9Y3Y2: nuclear localisation and no transmembrane segment). HPA reports supported nuclear-speckle localisation in ICC/IF, but that observation does not establish the catalog antibody's IF performance (HPA subcellular; datasheet A07770-2: tissue-IHC caption).
How do I distinguish background DAB from CHTOP staining?
Run a no-primary section to reveal signal from the detection system, and use a peroxidase block when applying an HRP/DAB workflow (standard IHC practice). The documented image used a goat-serum block, a peroxidase-conjugated secondary and DAB, but it does not establish which step will control background in another specimen (datasheet A07770-2). If diffuse brown staining obscures nuclei, compare primary-antibody titrations around the documented 2 μg/ml condition while keeping retrieval and development comparable (datasheet A07770-2; standard IHC practice). Check endogenous pigment, folds and section edges under the counterstain before calling a cell positive, and judge signal by nuclear localisation (standard IHC practice; HPA tissue IHC: nuclear expression).
How should I quantify CHTOP across specimens? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and tissue regions before scoring, then record the percentage of positive nuclei and nuclear intensity in each region (standard IHC practice; HPA tissue IHC: nuclear expression). An H-score can combine percentages at prespecified intensity grades, while positive nuclei per mm² describes spatial density; state which measure answers the biological question (standard IHC practice). Normalise positive-cell counts to the number of evaluable nuclei in the same cell population, or density to the analysed tissue area, and exclude necrotic or folded regions (standard IHC practice). Keep retrieval, DAB development, imaging and positivity thresholds consistent across the comparison, and report region-level variation rather than relying on one field (standard IHC practice).
When is a CHTOP-positive result credible rather than artefactual?
Treat staining as more credible when DAB aligns with intact nuclei, appears in the intended cell population and survives comparison with a no-primary control (HPA tissue IHC: nuclear expression; standard IHC practice). CHTOP has broad reported nuclear tissue expression, so a single positive cell type is not uniquely diagnostic; identify cells by morphology or a separate marker (HPA tissue IHC: nuclear expression in most tissues; standard IHC practice). Investigate signal limited to cut edges, folds, necrotic areas or pigment, and check whether endogenous peroxidase contributes to brown reaction product (standard IHC practice). Interpret discrepancies cautiously because the HPA tissue profile has medium consistency between antibody staining and RNA expression (HPA tissue IHC: Approved reliability description).
Boster reagents
Best CHTOP / Chromatin target of PRMT1 protein IHC Antibodies
A07770-2 has real IHC data from paraffin sections of human breast cancer, colorectal adenocarcinoma, laryngeal squamous cell carcinoma, and placenta (catalog IHC captions); no IF/ICC data are provided (catalog payload).
Real IHC data
Anti-C1orf77/FOP/CHTOP Antibody ®
Cat # A07770-2
A07770-2 is listed for IHC, WB, and flow cytometry, with stated reactivity to human, monkey, mouse, and rat (catalog applications and reactivity). Its IHC captions show paraffin sections of the four human tissues listed above; no IF/ICC application or image is listed (catalog IHC captions and applications).
Which to pick: Choose A07770-2 for human paraffin-section IHC because its own captions document staining in four human tissues (catalog IHC captions). There is no IF/ICC-validated SKU in this payload (catalog applications and images). A07770-2 lists monkey, mouse, and rat reactivity, but its IHC captions document only human tissue; the fixative is unreported (catalog reactivity and IHC captions).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry Q9Y3Y2 (CHTOP_HUMAN, Chromatin target of PRMT1 protein).
- Human Protein Atlas. CHTOP tissue IHC expression (reliability: Approved).
- Human Protein Atlas. CHTOP subcellular location (ICC-IF): Localized to the nuclear speckles..
- Human Protein Atlas. CHTOP antibody validation summary (2 antibodies).
- Chromatin target of protein arginine methyltransferase regulates invasion, chemoresistance, and stemness in epithelial ovarian cancer. Bioscience reports 2019 — PMC6465198.
- CHTOP in Chemoresistant Epithelial Ovarian Cancer: A Novel and Potential Therapeutic Target. Frontiers in oncology 2019 — PMC6660285.
- PubMed PMID:15498874 — UniProt-cited evidence.
- PubMed PMID:16710414 — UniProt-cited evidence.
- PubMed PMID:15489334 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for CHTOP (Chromatin target of PRMT1 protein). Expected localisation Nuclear in most tissues (HPA tissue IHC). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet A07770-2). Validated IHC antibody: A07770-2 at 2 μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Adipose tissue (Adipocytes); negative None in HPA (detected in all 45 tissues); use no-primary + isotype controls. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human breast cancer tissue; fixative not specified (datasheet A07770-2); 2. Fixation: Image fixative and duration unreported (datasheet A07770-2); 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 A07770-2); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet A07770-2); 8. Primary antibody: Rabbit anti-CHTOP, 2 μg/ml (datasheet A07770-2); 9. Primary incubation: Overnight at 4 °C (datasheet A07770-2). Watch for: Fixation: Keep fixation consistent across sections (standard IHC practice; not target-specific); Caveat: Hematopoietic cells may show strong staining (HPA tissue IHC); Isoform / epitope: 3 isoforms; epitope coverage is unknown (UniProt); Regulation: No abundance regulator specified (UniProt). Evidence: UniProt Q9Y3Y2, HPA tissue IHC · Approved, HPA ICC-IF · nuclear speckles., Datasheet A07770-2, PMC6465198, PMC6660285. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/CHTOP/immunohistochemistry-ihc-guide.