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SART1 / U4/U6.U5 tri-snRNP-associated protein 1 · IHC design guide
Design Immunohistochemistry for SART1
SART1 is a nuclear spliceosome component (UniProt), with nuclear staining in most cell types by tissue IHC (HPA tissue IHC). This guide helps plan paraffin-section staining using catalog antibody A05414-1 at 2–5 μg/ml (datasheet A05414-1) and interpret differences between cell populations (HPA tissue IHC).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
SART1 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 staining in most cell types (HPA tissue IHC) | |
| Staining pattern | Nuclear signal across most cell types (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet A05414-1) | |
| Positive control | Bronchus+4 more · see all | |
| Negative control | Adipose tissue+4 more · see all |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Keep tissue fixation consistent. (standard IHC practice; not target-specific) | |
| Caveat | Some cell populations show no detectable staining (HPA tissue IHC) | |
| Regulation | Preferential in proliferating cells (UniProt) | |
| Isoform / epitope | One isoform; a single 1–800 chain (UniProt) |
Section 1
Recommended SART1 IHC & IF Protocols
Compare the catalog antibody’s IHC-P protocol with the published SART1 protocol for paraffin liver sections (PMC5203921).
| Sample | Paraffin-embedded human colorectal adenocarcinoma tissue; fixative not specified (datasheet A05414-1) |
| Fixation | Image fixative and duration unreported (datasheet A05414-1); 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 A05414-1); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet A05414-1) |
| Primary antibody | Rabbit anti-SART1, 2-5 μg/ml (datasheet A05414-1) |
| Primary incubation | Overnight at 4 °C (datasheet A05414-1) |
| Detection | HRP-conjugated secondary, DAB chromogen (datasheet A05414-1) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | SART1-positive staining in respiratory epithelial cells of bronchus (HPA tissue IHC: High). HPA tissue profile: Nuclear expression in most cell types. No signal in the no-primary control. |
💡Decision noteStart with heat-mediated EDTA retrieval at pH 8.0 for the catalog antibody (datasheet A05414-1). The published liver protocol does not state a retrieval method (PMC5203921).
Section 2
What Is the Expected SART1 Staining Pattern?
SART1 should appear predominantly in nuclei across many cell types in paraffin-section IHC (HPA: nuclear expression in most cell types; reliability Supported, with medium consistency and pending external verification). Strong examples include bronchial respiratory epithelium, esophageal squamous epithelium, placental trophoblasts and stomach glands (HPA: High in these cells). Its spliceosomal role and lack of a transmembrane segment support a nuclear expectation (UniProt O43290: function and topology).
| Distinct nuclear staining in respiratory epithelial cells of bronchus, with interpretable nuclei and little background. | This matches a strong positive reference pattern (HPA: High in bronchial respiratory epithelial cells; nuclear expression in most cell types). Compare intensity within the same run rather than treating every nucleus as equally positive; the HPA tissue profile varies by cell type (HPA: High, Medium, Low and Not detected entries). |
| Predominantly membranous staining, or broad cytoplasmic staining without a convincing nuclear component. | Treat this as a compartment mismatch and investigate nonspecific signal or detection artefact (HPA: nuclear tissue profile; UniProt O43290: nucleus, no transmembrane segment). An additional Golgi location was observed by ICC-IF, so a limited extranuclear signal alone does not establish that an IHC slide is specific (HPA: supported additional Golgi localization in ICC-IF). |
| Strong staining in adipocytes, alveolar cells or cardiomyocytes while the intended positive cells are weak. | Question specificity or endogenous chromogen-generating activity before scoring this as SART1 (HPA: Not detected in those named cell types; general chromogenic IHC practice). “Not detected” describes HPA observations, not an absolute biological absence; the antibody, detection system and tissue processing still need appropriate controls (HPA: tissue IHC profile; general IHC practice). |
| Uniform haze across tissue, including areas between cells, obscures nuclear boundaries. | This is uninterpretable background rather than evidence of broad SART1 expression (HPA: expected nuclear tissue profile; general IHC practice). Review blocking, antibody concentration, washes and chromogen development with a no-primary control; these are general assay checks, not documented SART1-specific sensitivities (general chromogenic IHC practice). |
| No visible nuclear signal in bronchial respiratory epithelium or placental trophoblasts. | A failed run, weak detection or an unsuitable antibody condition is possible because both are reported High (HPA: High in bronchial respiratory epithelial cells and placental trophoblasts). Check section quality and a same-run positive control before calling the sample negative; HPA reliability is Supported and pending external verification (HPA: reliability description; general IHC practice). |
💡Expected SART1 appearanceCall a slide positive when nuclei of an HPA High cell population, such as bronchial respiratory epithelium, show clear chromogenic signal above local background; isolated membrane staining or diffuse haze does not match the expected pattern (HPA: High in bronchial respiratory epithelial cells; nuclear expression in most cell types; UniProt O43290: no transmembrane segment).
| Which tissue and cells provide a useful comparison? | Use an HPA High population, such as esophageal squamous epithelial cells, alongside the study tissue; appendix glandular cells are Medium, while adipocytes are Not detected (HPA: tissue IHC profile). These are cell-specific observations, so whole-section staining should not be reduced to a single tissue-wide score (HPA: named cell-type levels). |
| How strong is the IHC localization evidence? | The tissue pattern has Supported reliability, described as medium consistency with RNA and pending external verification (HPA: tissue IHC reliability). HPA031188 and HPA031189 each have IHC Supported status; HPA031190 has no supplied IHC status (HPA: antibody validation entries). Interpret a discrepant slide with controls rather than treating the reference pattern as infallible. |
| Could processing or topology change the expected compartment? | UniProt lists one isoform, a chain spanning residues 1–800, no signal peptide or propeptide, and no transmembrane segment (UniProt O43290: isoform, processing and topology). The supplied record gives no cleavage, shedding or tissue-specific epitope-access result; none should be invoked to explain an absent nuclear stain (UniProt O43290: processing record). |
| Does antigen retrieval have a SART1-specific setting? | No target-specific fixation or retrieval effect is established by these sources (HPA: tissue staining and antibody status; UniProt O43290: protein annotations). For paraffin IHC, assess retrieval against a same-run positive section and follow the IHC-validated antibody’s documented conditions where available (general IHC practice). Do not infer an optimal retrieval condition from HPA intensity or UniProt phosphorylation sites. |
| What should IF/ICC show? | In its separate IF/ICC assay, expect mainly nuclear speckles, with an additional supported Golgi location (HPA: enhanced nuclear-speckle and supported Golgi ICC-IF localizations). This answers the localization question only; the ICC-IF observation does not supply an IHC protocol or prove that chromogenic paraffin sections will resolve speckles (HPA: subcellular ICC-IF profile). |
| Situation | Likely cause | Next action |
|---|---|---|
| Known-positive epithelium is blank in the same run. | Primary-antibody or detection conditions may have failed; the named epithelium is an HPA High reference (HPA: High in bronchial respiratory or esophageal squamous epithelial cells). | Verify control-section integrity, antibody use and detection reagents; then assess the documented paraffin-IHC retrieval conditions (general IHC practice). The sources do not establish a SART1-specific fixation sensitivity. |
| Signal is mostly at cell borders. | That distribution conflicts with the nuclear expectation and lacks support from the annotated topology (HPA: nuclear tissue profile; UniProt O43290: no transmembrane segment). | Review the no-primary control, chromogen deposition and primary-antibody dilution; repeat with an IHC Supported antibody if needed (general IHC practice; HPA: HPA031188 and HPA031189 IHC Supported). |
| Unexpected cells stain more strongly than the positive reference. | Cross-reactivity or endogenous detection activity is possible when staining appears in cells HPA lists as Not detected (HPA: adipocytes, alveolar cells and cardiomyocytes Not detected; general chromogenic IHC practice). | Compare matched sections with no-primary and detection controls, then score named cell populations separately (general IHC practice; HPA: cell-specific tissue profile). |
| Brown haze prevents nuclear scoring. | Background from concentrated primary antibody, incomplete washes or overdeveloped chromogen can obscure compartment assignment (general chromogenic IHC practice). | Adjust the general assay conditions against a same-run positive control and confirm that nuclear boundaries become readable (general IHC practice; HPA: expected nuclear profile). |
| A specimen is called negative because one cell type is unstained. | HPA reports differing levels within its tissue survey, including High, Low and Not detected cell populations (HPA: tissue IHC profile). | Record the cell population and nuclear intensity separately, and compare with a named HPA reference population; do not extend a negative call to the entire section (HPA: cell-specific tissue profile; general IHC scoring practice). |
| A punctate or Golgi-like signal is used to validate the paraffin IHC result. | Those finer locations come from ICC-IF, whereas HPA summarizes tissue IHC as nuclear (HPA: subcellular ICC-IF profile and tissue IHC profile). | Judge chromogenic IHC by interpretable nuclear staining in the expected cells and assay controls; consult the separate IF/ICC guide for that application (HPA: tissue IHC profile; general IHC practice). |
Experiment evidence
IHC & IF images showing SART1 staining
A05414-1 · IHCIHC analysis of SART1 using anti-SART1 antibody (A05414-1). SART1 was detected in a paraffin-embedded section of human colorectal adenocarci
A05414-1 · IHCIHC analysis of SART1 using anti-SART1 antibody (A05414-1). SART1 was detected in a paraffin-embedded section of human ovarian cancer tissue
A05414-1 · IFIF analysis of SART1 using anti-SART1 antibody (A05414-1) and anti-Beta Tubulin antibody (M01857-3). SART1 was detected in immunocytochemica
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000175467-SART1/tissue/cerebral+cortex#imid_7951857
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000175467-SART1/tissue/colon#imid_7942858
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000175467-SART1/tissue/liver#imid_7942875
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000175467-SART1/tissue/kidney#imid_7942876
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA031188; green = SART1, blue = nucleus, red = microtubules.
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA031188; green = SART1, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for SART1 IHC & IF
🧪Run bronchus first: respiratory epithelial cells should stain (HPA: High in bronchus). Use adipose tissue as the negative tissue; adipocytes are listed as not detected (HPA: Not detected in adipocytes), while morphologically distinct cells without nuclear DAB staining on the bronchus slide can serve as an internal background reference rather than an assumed negative cell type.
Positive control tissue: Bronchus (Respiratory epithelial cells, HPA High)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show SART1 in A-431, U-251MG, U2OS, with annotated localisation: Nuclear speckles (enhanced) (HPA subcellular).
Technical controls: Include no-primary (secondary-only) and concentration-matched rabbit IgG isotype controls, plus SART1 knockout material or peptide blocking if a suitable peptide is available (standard IHC practice; selected-SKU caption: rabbit primary). For bronchus, quench endogenous peroxidase and inspect mucus for nonspecific DAB retention (standard IHC practice).
⚠️Feasibility: A target-specific fixation window or fixation effect is unreported, and the selected A05414-1 paraffin-section caption does not state the fixative (selected-SKU caption). The caption uses heat-mediated EDTA retrieval at pH 8.0, but does not establish that retrieval is required; the supplied evidence does not establish whether frozen sections or IF are easier (selected-SKU caption; HPA: ICC-IF images available). In bronchus, inspect mucus-associated DAB background against the negative controls (standard IHC practice).
HPA tissue IHC evidence for SART1
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Supported — Medium 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 |
|---|---|---|---|---|
| Bronchus | Respiratory epithelial cells | High | Protein (IHC) | HPA → |
| Esophagus | Squamous epithelial cells | High | Protein (IHC) | HPA → |
| Nasopharynx | Respiratory epithelial cells | High | Protein (IHC) | HPA → |
| Oral mucosa | Squamous epithelial cells | High | Protein (IHC) | HPA → |
| Placenta | Trophoblastic cells | High | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Adipose tissue | Adipocytes | Not detected | Protein (IHC) | HPA → |
| Bone marrow | Hematopoietic cells | Not detected | Protein (IHC) | HPA → |
| Endometrium | Cells in endometrial stroma | Not detected | Protein (IHC) | HPA → |
| Fallopian tube | Glandular cells | Not detected | Protein (IHC) | HPA → |
| Heart muscle | Cardiomyocytes | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced SART1 IHC Tips
Troubleshoot SART1 chromogenic IHC by checking retrieval, nuclear staining, controls, and scoring; apply separate validation criteria when using IF.
What should I change when SART1 staining is weak after antigen retrieval?
Use heat-mediated EDTA at pH 8.0 for antigen retrieval before chromogenic IHC (datasheet A05414-1). This is the retrieval used for the catalog antibody in a paraffin-embedded human colorectal adenocarcinoma section, followed by 2 μg/ml primary antibody overnight at 4°C (caption A05414-1). If nuclear staining remains weak, first check deparaffinisation, heating consistency, and whether the control section survived retrieval (standard IHC practice). Then compare retrieval duration, or test another buffer as a fallback, using adjacent sections and identical detection conditions (standard IHC practice). Judge improvement by nuclear signal with limited background, since SART1 is nuclear and HPA reports nuclear expression in most cell types (UniProt O43290; HPA tissue IHC).
Could fixation explain weak SART1 staining in paraffin sections?
The selected tissue-IHC caption identifies a paraffin-embedded section but does not state its fixative, so target-specific fixation sensitivity is unknown (caption A05414-1). Record the specimen's actual fixative and fixation duration before comparing runs; do not infer them from the staining image (standard IHC practice; caption A05414-1). For suspected masking, process matched sections consistently and first apply heat-mediated EDTA at pH 8.0, the documented retrieval for this antibody (datasheet A05414-1). Compare nuclear staining in a reference section while holding the 2 μg/ml primary concentration and overnight 4°C incubation constant (caption A05414-1). A fixation effect requires that controlled comparison; nuclear localisation or phosphorylation alone does not establish one (UniProt O43290; standard IHC practice).
Should SART1 appear only in nuclei on chromogenic sections?
Expect predominantly nuclear staining in tissue IHC: HPA reports nuclear expression in most cell types, and UniProt places SART1 in the nucleus (HPA tissue IHC; UniProt O43290). HPA IF images refine that pattern to mainly nuclear speckles with an additional Golgi location, but chromogenic tissue sections may not resolve individual speckles (HPA subcellular; standard microscopy practice). Compare staining with a nuclear counterstain and score nuclei separately from diffuse cytoplasm (standard IHC practice). Persistent cytoplasmic or perinuclear signal merits review of morphology, background controls, and the antibody's tissue-IHC performance before assigning a compartment (standard IHC practice). Do not require identical intensity in every cell, given HPA's cell-type-specific staining levels (HPA tissue IHC).
Could an isoform or modified epitope explain inconsistent SART1 staining?
UniProt lists one SART1 isoform and a single 1–800 chain, so an annotated isoform switch is not an established explanation for discordant sections (UniProt O43290). The record lists 17 modified residues, including phosphorylation at residues 189, 321, and 348, but the antibody epitope is not supplied (UniProt O43290; caption A05414-1). Do not attribute staining loss to a particular modification without epitope mapping or direct validation (standard antibody-validation practice). Compare adjacent sections with the documented EDTA pH 8.0 retrieval and a reference section in the same run (datasheet A05414-1; standard IHC practice). SART1 has no annotated transmembrane segment, which does not establish antibody accessibility after processing (UniProt O43290).
How should I adapt SART1 localisation checks to multiplex IF?
For IF, pair SART1 with a marker identifying the cell population under study and a nuclear counterstain, then assess overlap within individual cells (standard IF practice). HPA reports mainly nuclear-speckle localisation and an additional Golgi location in ICC/IF images; those images do not validate this catalog antibody's IF performance (HPA subcellular). Choose a fluorophore channel with low specimen autofluorescence and include single-stain controls to assess bleed-through (standard IF practice). Because SART1 is nuclear and has no transmembrane segment, permeabilise sufficiently for nuclear antibody access; its precise antibody epitope is unreported (UniProt O43290; standard IF practice; caption A05414-1). Optimise IF fixation independently, since the selected paraffin-section caption does not report a fixative (caption A05414-1).
How can I reduce diffuse or false-positive SART1 DAB staining?
Start by separating diffuse deposit from nuclear signal with a counterstain; HPA reports nuclear expression in most cell types (HPA tissue IHC; standard IHC practice). The selected image used 10% goat serum blocking, 2 μg/ml primary antibody overnight at 4°C, a peroxidase-conjugated secondary, and DAB development (caption A05414-1). Include a no-primary section to identify secondary or detection-system staining, and use a peroxidase block to assess endogenous enzyme activity (standard chromogenic IHC practice). If background persists, check wash conditions and titrate primary concentration or DAB development while retaining a reference section (standard IHC practice). Avoid calling widespread cytoplasmic brown signal SART1 solely because some cells also stain in their nuclei (UniProt O43290; standard IHC practice).
What is a defensible way to quantify SART1 IHC across samples? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and analysis region before scoring, then count nuclear SART1 staining separately from cytoplasmic or stromal signal (HPA tissue IHC; standard IHC practice). For a nuclear H-score, record the percentage of eligible cells at each intensity 0–3 and sum percentage times intensity; report the percentage of positive nuclei alongside it (standard IHC scoring practice). If counting cells per area, express positive nuclei per mm² and also report eligible nuclei per mm² so cellularity is visible (standard image-analysis practice). Normalise comparisons to the same cell population, section area rules, staining batch, and exposure or scan settings (standard IHC practice). HPA reports different staining levels across cell types, making composition a potential confounder (HPA tissue IHC).
When is an apparent SART1-positive cell likely to be an artefact?
Prioritise staining that aligns with intact nuclei in the expected cell population: SART1 is nuclear, and HPA reports nuclear expression in most cell types (UniProt O43290; HPA tissue IHC). Check edge-only staining, necrotic areas, and diffuse DAB deposit against morphology and a no-primary control before calling cells positive (standard chromogenic IHC practice). Persistent signal in that control can implicate the detection system or endogenous enzyme activity rather than primary-antibody binding (standard chromogenic IHC practice). Do not treat every unstained cell as technical failure; HPA reports high staining in some cell populations and undetected staining in others (HPA tissue IHC). Its tissue-IHC reliability is Supported, with medium agreement to RNA and external verification pending, so resolve unexpected patterns with independent evidence (HPA tissue IHC).
Boster reagents
Best SART1 / U4/U6.U5 tri-snRNP-associated protein 1 IHC Antibodies
A05414-1 has human paraffin-section IHC images and human cell and tissue IF images (catalog image captions); Human, Mouse and Rat reactivity is listed (catalog reactivity).
Real IHC data
Anti-SART1 Antibody ®
Cat # A05414-1
A05414-1 has IHC images from paraffin sections of human colorectal adenocarcinoma, ovarian cancer, breast cancer and laryngeal squamous cell carcinoma (catalog IHC image captions). The same SKU has IF images from A549 cells and a paraffin section of human breast cancer (catalog IF image captions).
Which to pick: Choose A05414-1 for chromogenic IHC on human paraffin sections: its colorectal adenocarcinoma image used EDTA retrieval at pH 8.0, 2 μg/ml primary antibody and DAB detection (A05414-1 IHC image caption); the fixative is unreported (A05414-1 IHC image caption). Choose A05414-1 for IF/ICC because those applications are listed and its IF images show A549 cells and human breast cancer tissue (catalog applications; catalog IF image captions). For cross-species work, A05414-1 lists Human, Mouse and Rat reactivity, while the supplied IHC images show human tissue (catalog reactivity; catalog IHC image captions); it is rabbit-hosted, with no clone specified (catalog host and clone fields).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry O43290 (SNUT1_HUMAN, U4/U6.U5 tri-snRNP-associated protein 1).
- Human Protein Atlas. SART1 tissue IHC expression (reliability: Supported).
- Human Protein Atlas. SART1 subcellular location (ICC-IF): Mainly localized to the nuclear speckles. In addition localized to the Golgi apparatus..
- Human Protein Atlas. SART1 antibody validation summary (3 antibodies).
- Expression of Interferon Effector Gene SART1 Correlates with Interferon Treatment Response against Hepatitis B Infection. Mediators of inflammation 2016 — PMC5203921.
- PubMed PMID:9449708 — UniProt-cited evidence.
- PubMed PMID:11350945 — UniProt-cited evidence.
- PubMed PMID:16554811 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for SART1 (U4/U6.U5 tri-snRNP-associated protein 1). Expected localisation Nuclear staining in most cell types (HPA tissue IHC). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet A05414-1). Validated IHC antibody: A05414-1 at 2-5 μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Bronchus (Respiratory epithelial cells); negative Adipose tissue. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human colorectal adenocarcinoma tissue; fixative not specified (datasheet A05414-1); 2. Fixation: Image fixative and duration unreported (datasheet A05414-1); 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 A05414-1); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet A05414-1); 8. Primary antibody: Rabbit anti-SART1, 2-5 μg/ml (datasheet A05414-1); 9. Primary incubation: Overnight at 4 °C (datasheet A05414-1). Watch for: Fixation: Keep tissue fixation consistent. (standard IHC practice; not target-specific); Caveat: Some cell populations show no detectable staining (HPA tissue IHC); Isoform / epitope: One isoform; a single 1–800 chain (UniProt); Regulation: Preferential in proliferating cells (UniProt). Evidence: UniProt O43290, HPA tissue IHC · Supported, HPA ICC-IF · Mainly localized to the nuclear speckles. In addition localized to…, Datasheet A05414-1, PMC5203921. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/SART1/immunohistochemistry-ihc-guide.