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IST1 / IST1 homolog · IHC design guide
Design Immunohistochemistry for IST1
Plan IST1 paraffin IHC using the cytoplasmic and nuclear tissue pattern, with colon glandular cells as a high-staining reference (HPA tissue IHC). The guide covers fixation, staining controls and interpretation for the IHC-validated antibody A05507-2 (datasheet A05507-2).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
IST1 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 nuclear staining in most tissues (HPA tissue IHC) | |
| Staining pattern | Most tissues show cytoplasmic and nuclear staining (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet A05507-2) | |
| Positive control | Adipose tissue+4 more · see all | |
| Negative control | None in HPA (detected in all 43 tissues); use no-primary + isotype controls |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Keep fixation conditions consistent across sections. (standard IHC practice; not target-specific) | |
| Caveat | Staining and RNA levels have medium consistency (HPA tissue IHC) | |
| Regulation | RNA has low tissue specificity (HPA tissue RNA) | |
| Isoform / epitope | 6 isoforms; antibody epitope coverage is unclear (UniProt; datasheet A05507-2) |
Section 1
Recommended IST1 IHC & IF Protocols
The catalog antibody’s IHC-P protocol (datasheet: A05507-2) is paired with a published IST1 stain of paraffin-embedded tissue (PMC10200693).
| Sample | Paraffin-embedded human breast cancer tissue; fixative not specified (datasheet A05507-2) |
| Fixation | Image fixative and duration unreported (datasheet A05507-2); 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 A05507-2); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet A05507-2) |
| Primary antibody | Rabbit anti-IST1, 2-5 μg/ml (datasheet A05507-2) |
| Primary incubation | Overnight at 4 °C (datasheet A05507-2) |
| Detection | HRP-conjugated secondary, DAB chromogen (datasheet A05507-2) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | IST1-positive staining in adipocytes of adipose tissue (HPA tissue IHC: High). HPA tissue profile: Cytoplasmic and nuclear expression in most tissues. No signal in the no-primary control. |
💡Decision noteStart with heat-mediated EDTA retrieval at pH 8.0 (datasheet: A05507-2); the published method used microwave tris-EDTA at pH 9 for 15 min (PMC10200693).
Section 2
What Is the Expected IST1 Staining Pattern?
IST1 should show cytoplasmic and nuclear staining in many tissues, including strong staining in several epithelial, adipocyte and hematopoietic populations (HPA tissue IHC: High; profile: cytoplasmic and nuclear). Vesicular signal is consistent with its reported localization; dividing cells may also show centrosomal, midbody or reforming nuclear envelope signal (UniProt P53990: subcellular location). IST1 has no transmembrane segment (UniProt P53990: topology). HPA rates the tissue IHC pattern Approved, with medium consistency against RNA expression (HPA tissue IHC: reliability).
| Cytoplasmic staining, with some nuclear staining, in colon or appendix glandular cells. | This fits the reported broad tissue pattern and the High staining recorded for these cells (HPA tissue IHC: profile; High in colon and appendix glandular cells). Judge the intended cells against neighboring tissue and the same staining run; a positive result need not have identical intensity in every cell (general IHC interpretation). |
| A small, discrete signal appears near the division plane of a dividing cell. | A midbody-associated pattern is biologically plausible because IST1 localizes to the midbody and helps recruit VPS4 proteins during cytokinesis (UniProt P53990: location and function). In a paraffin section, a single dot is insufficient proof of a midbody; confirm cell morphology and reproducibility before assigning that structure (general IHC interpretation). |
| The dominant signal outlines the plasma membrane or fills extracellular spaces. | That distribution conflicts with the reported cytoplasmic and nuclear tissue pattern and the absence of a transmembrane segment (HPA tissue IHC: profile; UniProt P53990: topology). Review morphology and controls for deposited chromogen or nonspecific staining before interpreting the outline as IST1 (general IHC interpretation). |
| An unexpected cell population stains while the expected cells do not. | Consider antibody cross-reactivity or endogenous detection activity, then inspect the positive control and control lacking primary antibody (general IHC troubleshooting). Cell identity alone is not proof of a false positive: HPA reports expression in most tissues and low RNA tissue specificity (HPA tissue IHC: profile and RNA specificity). |
| Staining is diffuse across cells, stroma and the slide, or absent in an expected positive tissue. | Diffuse signal obscures the reported cellular pattern; absent signal in an expected High population prevents a reliable negative call (HPA tissue IHC: profile; High in specified cells). Compare controls, section quality and the detection run before attributing either result to IST1 biology (general IHC interpretation). |
💡Expected IST1 appearanceCall a positive result when cytoplasmic staining, with possible nuclear staining, is discernible in an HPA High population such as colon glandular cells; treat dominant extracellular or plasma membrane outlining as suspect (HPA tissue IHC: profile; High in colon glandular cells; UniProt P53990: topology).
| Choice of reference tissue and cell population | HPA reports High staining in adipocytes, several glandular or respiratory epithelial populations, and bone marrow hematopoietic cells, but Low staining in cardiomyocytes (HPA tissue IHC: listed cells). Compare the relevant cell population, rather than treating an entire section as uniformly positive or negative (general IHC interpretation). |
| Cell state and compartment | IST1 is reported at cytoplasmic vesicles and, in dividing cells, at the centrosome, midbody and reforming nuclear envelope (UniProt P53990: subcellular location). Those structures need suitable cell morphology and resolution for assignment; routine chromogenic IHC may show a broader cytoplasmic or nuclear pattern (HPA tissue IHC: profile; general IHC interpretation). |
| Antibody evidence | Two listed antibodies have Approved IHC status, while the tissue pattern has medium consistency with RNA data (HPA antibodies: IHC Approved; HPA tissue IHC: reliability). Use the observed pattern as a reference with that limitation; the supplied record does not establish an Enhanced IHC validation claim (HPA antibodies: listed status). |
| Isoforms and epitope coverage | Six isoforms are listed, but the supplied record gives no antibody epitope or isoform coverage (UniProt P53990: isoforms; supplied antibody record). Do not infer which isoforms a stained or unstained cell contains from this IHC result alone (general IHC interpretation). |
| Processing and fixation evidence | The listed IST1 chain spans residues 1–364, with no signal peptide, propeptide or glycosylation site reported (UniProt P53990: processing and glycosylation). These facts do not establish how fixation or antigen retrieval affects staining; target-specific fixation sensitivity is unreported in the supplied sources. |
| Situation | Likely cause | Next action |
|---|---|---|
| No signal in colon or appendix glandular cells expected to stain strongly. | A failed staining run is possible; these are High populations in the HPA tissue record (HPA tissue IHC: High in colon and appendix glandular cells). | Check tissue identity, section integrity, primary antibody application and detection controls, then review retrieval conditions using the antibody's validated IHC instructions (general IHC practice). Do not call the tissue IST1-negative until the run controls work. |
| Signal is weak but present in the reference cell population. | Low signal may reflect the staining workflow; apparent strength also depends on which cells are being compared (general IHC practice). Cardiomyocytes are listed as Low, so they are a poor strong-signal reference (HPA tissue IHC: Low in cardiomyocytes). | Compare like cell populations within the same run and use an HPA High population as a positive reference (HPA tissue IHC: listed levels). Review antibody dilution, retrieval and detection settings against the applicable IHC instructions (general IHC practice). |
| Brown staining spreads through stroma or appears at section edges. | Background deposition or nonspecific binding can obscure cellular staining (general chromogenic IHC practice). It does not match HPA's cytoplasmic and nuclear tissue profile (HPA tissue IHC: profile). | Inspect a control lacking primary antibody, wash and blocking steps, and whether the signal follows intact cell boundaries (general IHC practice). Score IST1 only where a reproducible cellular pattern remains interpretable. |
| The strongest signal forms a continuous cell-surface rim. | A dominant membrane outline is discordant with the reported pattern and with IST1's lack of a transmembrane segment (HPA tissue IHC: profile; UniProt P53990: topology). | Check the control lacking primary antibody and repeat with the validated IHC conditions if needed (general IHC practice). Do not reinterpret a membrane rim as the expected vesicular pattern without supporting cellular morphology (HPA subcellular ICC-IF: vesicles supported). |
| Bone marrow cells appear positive even in a control lacking primary antibody. | Endogenous detection activity can produce chromogenic signal independently of the primary antibody (general chromogenic IHC practice). Bone marrow hematopoietic cells are also listed as High, so the control matters here (HPA tissue IHC: High in bone marrow hematopoietic cells). | Review the detection system's endogenous-activity blocking step and compare control and test sections under the same conditions (general IHC practice). Interpret residual cellular staining only after control-derived signal is accounted for. |
| IF/ICC: Should vesicular puncta count as IST1 localization? | HPA reports vesicles as a supported main ICC-IF location; the IHC tissue profile is broader, with cytoplasmic and nuclear expression (HPA subcellular ICC-IF: vesicles supported; HPA tissue IHC: profile). | Use the separate IF/ICC guide for that application. Here, treat puncta as compatible with the supported localization when controls and cell morphology support them; do not transfer an IF pattern or workflow directly into a chromogenic paraffin-section interpretation (general IHC/IF practice). |
Experiment evidence
IHC & IF images showing IST1 staining
A05507-2 · IHCIHC analysis of HIST1/IST1 using anti-HIST1/IST1 antibody (A05507-2). HIST1/IST1 was detected in a paraffin-embedded section of human breast
A05507-2 · IHCIHC analysis of HIST1/IST1 using anti-HIST1/IST1 antibody (A05507-2). HIST1/IST1 was detected in a paraffin-embedded section of human breast
A05507-2 · IFIF analysis of HIST1/IST1 using anti-HIST1/IST1 antibody (A05507-2). HIST1/IST1 was detected in an immunocytochemical section of U2OS cells.
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000182149-IST1/tissue/cerebral+cortex#imid_11056263
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000182149-IST1/tissue/colon#imid_11061661
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000182149-IST1/tissue/liver#imid_11061670
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000182149-IST1/tissue/kidney#imid_11061655
HPA · ICC-IF HAP1Human Protein Atlas immunofluorescence, HAP1, antibody HPA054532; green = IST1, blue = nucleus, red = microtubules.
HPA · ICC-IF HAP1Human Protein Atlas immunofluorescence, HAP1, antibody HPA054532; green = IST1, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for IST1 IHC & IF
🧪Run breast first and assess staining in its adipocytes (HPA: High in breast adipocytes). HPA detects IST1 in all 43 scored tissues, so no negative tissue is available; use no-primary and isotype controls, and treat any faint neighboring cells as a background reference rather than validated IST1-negative cells (HPA: no negative rows; standard IHC control practice).
Positive control tissue: Adipose tissue (Adipocytes, HPA High)
Negative control tissue: None in HPA: IST1 is detected in all 43 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 IST1 in HAP1, MCF-7, U2OS, RPTEC/TERT1, hTERT-RPE1 (serum starved), with annotated localisation: Vesicles (supported) (HPA subcellular).
Technical controls: Include a no-primary, secondary-only section, a rabbit IgG isotype control matched to the catalog antibody’s clonality, and IST1 knockout material if available (catalog caption: rabbit primary; standard IHC control practice). Quench endogenous peroxidase before chromogenic detection and check adipose-rich areas for nonspecific DAB signal (standard chromogenic IHC practice).
⚠️Feasibility: No target-specific fixation window or fixation effect is reported, and the selected A05507-2 paraffin-section caption does not state its fixative (catalog caption: fixative unreported). Heat retrieval in EDTA at pH 8.0 is a documented starting condition, but the caption does not establish that retrieval is required (catalog caption: heat retrieval in EDTA, pH 8.0). Paraffin processing can leave adipocytes with thin cytoplasmic rims that complicate scoring (standard paraffin histology); HPA supports vesicular IF/ICC localization, but the supplied evidence does not show that IF or frozen sections are easier (HPA: vesicles, supported).
HPA tissue IHC evidence for IST1
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 → |
| Appendix | Glandular cells | High | Protein (IHC) | HPA → |
| Bone marrow | Hematopoietic cells | High | Protein (IHC) | HPA → |
| Breast | Adipocytes | High | Protein (IHC) | HPA → |
| Bronchus | Respiratory epithelial cells | High | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| None in HPA: IST1 is detected in all 43 scored tissues. Use a no-primary (secondary-only) and an isotype control instead. | ||||
Section 3
Advanced IST1 IHC Tips
Troubleshoot IST1 staining in paraffin sections by checking retrieval, cell compartment, controls, and scoring before interpreting a chromogenic signal.
What retrieval should I try first for IST1 paraffin sections?
Start with heat-mediated antigen retrieval in EDTA at pH 8.0 for IST1 paraffin-section IHC (datasheet A05507-2). Keep heating and cooling conditions consistent across sections, then compare staining with a matched control section processed in the same run (standard IHC practice). The documented example used this retrieval before 2 μg/ml primary antibody overnight at 4°C, so change one variable at a time if staining is weak (caption A05507-2). If signal remains weak, test another retrieval buffer or heating duration on adjacent sections while watching for tissue damage and increased background (standard IHC practice).
How should I handle fixation when IST1 staining varies between blocks?
The selected paraffin-section caption does not identify its fixative, so IST1-specific sensitivity to fixation is unknown (caption A05507-2). Record the fixative, fixation duration, tissue thickness, and processing history for each block before attributing differences to IST1 abundance (standard IHC practice). Compare adjacent sections from similarly processed blocks using the same EDTA pH 8.0 retrieval and antibody conditions (datasheet A05507-2; standard IHC practice). Where fixation history differs, assess morphology and a suitable staining control alongside IST1; neither the tissue staining profile nor the protein’s topology establishes a fixation effect (HPA: tissue IHC profile; UniProt P53990: no transmembrane segment).
Which staining compartments are plausible for IST1 in tissue sections?
Assess diffuse or punctate cytoplasmic staining alongside nuclear staining, since both occur in tissue IHC and vesicles are a supported subcellular location (HPA: tissue IHC; HPA: subcellular). IST1 can also localize to centrosomes, midbodies, and the reforming nuclear envelope during cell division (UniProt P53990: subcellular location). Those small structures may be difficult to resolve with chromogenic light microscopy, so use cell morphology and a counterstain before assigning a punctum to one of them (standard IHC practice). Score cytoplasmic and nuclear signals separately, and avoid treating a membrane rim as expected simply because the protein has endosomal functions (UniProt P53990: function and no transmembrane segment; standard IHC practice).
Could isoforms or epitope accessibility explain discordant IST1 staining?
IST1 has 6 annotated isoforms, but the supplied IHC caption does not identify the antibody epitope or establish isoform coverage (UniProt P53990: isoforms; caption A05507-2). Check the antibody’s immunogen information before interpreting a negative compartment as absence of every IST1 isoform (standard IHC practice). The protein has no annotated transmembrane segment, and phosphorylation is recorded at residues 4 and 43; neither fact establishes whether this antibody recognizes a modified epitope (UniProt P53990: topology and modified residues). If sections disagree, compare matched processing and retrieval first, then use an independently characterized antibody where its epitope information permits a meaningful comparison (standard IHC practice).
How can IF help resolve an ambiguous IST1 IHC pattern?
Use IF as a companion check when DAB staining cannot resolve a suspected vesicular or division-associated pattern; vesicles are a supported location, while centrosomes and midbodies are reported during division (HPA: subcellular; UniProt P53990: subcellular location). Multiplex IST1 with a marker identifying the expected cell type, choosing that marker from the actual specimen and question rather than assuming every stained cell is equivalent (standard IF practice). Choose fluorophores after checking the specimen’s autofluorescence and acquire single-color controls to assess bleed-through (standard IF practice). Because IST1 lacks a transmembrane segment, optimize permeabilisation for access to its intracellular epitope once that epitope is known (UniProt P53990: topology; standard IF practice).
What should I check if IST1 DAB staining is widespread?
First distinguish cellular signal from diffuse deposits, section edges, and staining in areas of poor morphology using a counterstained section (standard IHC practice). The documented example blocked with 10% goat serum and used a peroxidase-linked secondary followed by DAB, providing a starting point for comparison with matched controls (caption A05507-2). Include a no-primary control and apply a peroxidase block when using HRP detection to assess background from the detection workflow (standard IHC practice). Because HPA reports cytoplasmic and nuclear expression in most tissues, widespread cellular staining alone is not proof of nonspecific binding; compare compartments, intensity, and controls together (HPA: tissue IHC; standard IHC practice).
How should I quantify IST1 staining across paraffin sections? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and compartment before scoring, because tissue IHC reports both cytoplasmic and nuclear IST1 expression (HPA: tissue IHC). For chromogenic sections, record the percentage of positive cells and an intensity score, or calculate an H-score from prespecified intensity categories (standard IHC practice). If spatial abundance matters, report positive-cell density per mm² of viable tissue and exclude folds, necrosis, and section edges by a consistent rule (standard IHC practice). Normalize comparisons to the same tissue area or cell population, keep retrieval and imaging conditions fixed, and analyze matched controls alongside specimens (standard IHC practice).
How do I distinguish genuine IST1 staining from artefact?
A credible pattern should align with identifiable cells and the reported cytoplasmic or nuclear tissue staining; vesicular signal is also supported by subcellular imaging (HPA: tissue IHC; HPA: subcellular). A small midbody or centrosomal focus can be plausible in a dividing cell, but that assignment needs compatible morphology and adequate resolution (UniProt P53990: subcellular location; standard IHC practice). Review unexpected sharp membrane outlines, section-edge staining, necrotic areas, and signal persisting in a no-primary control before calling a region positive (standard IHC practice). With HRP and DAB detection, a peroxidase block and appropriate controls help distinguish target staining from endogenous enzyme activity and detection background (caption A05507-2: detection method; standard IHC practice).
Boster reagents
Best IST1 / IST1 homolog IHC Antibodies
A05507-2 has human paraffin-section IHC images and a U2OS cell IF image (catalog image captions). Listed reactivity covers human, mouse, and rat (catalog reactivity).
Real IHC data
Anti-hIST1/IST1 Antibody ®
Cat # A05507-2
A05507-2 is shown in paraffin sections of human breast cancer and colon adenocarcinoma (catalog IHC image captions). The same SKU is shown in U2OS cells by IF and is listed for IHC, ICC, and IF (catalog IF image caption; catalog applications).
Which to pick: Choose A05507-2 for human paraffin-section IHC: its own captions show staining at 2 μg/ml after EDTA retrieval at pH 8.0; the fixative is unreported (catalog IHC image captions). For IF/ICC, the same SKU has a U2OS cell IF image at 5 μg/ml (catalog IF image caption). For mouse or rat samples, this SKU lists reactivity with both species, but its supplied IHC and IF images show human samples only; clonality is unreported (catalog reactivity; catalog image captions; catalog clone field).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry P53990 (IST1_HUMAN, IST1 homolog).
- Human Protein Atlas. IST1 tissue IHC expression (reliability: Approved).
- Human Protein Atlas. IST1 subcellular location (ICC-IF): Localized to vesicles..
- Human Protein Atlas. IST1 antibody validation summary (2 antibodies).
- Giant worm-shaped ESCRT scaffolds surround actin-independent integrin clusters. The Journal of cell biology 2023 — PMC10200693.
- An ESCRT-spastin interaction promotes fission of recycling tubules from the endosome. The Journal of cell biology 2013 — PMC3734076.
- PubMed PMID:8724849 — UniProt-cited evidence.
- PubMed PMID:12761501 — UniProt-cited evidence.
- PubMed PMID:14702039 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for IST1 (IST1 homolog). Expected localisation Cytoplasmic and nuclear staining in most tissues (HPA tissue IHC). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet A05507-2). Validated IHC antibody: A05507-2 at 2-5 μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Adipose tissue (Adipocytes); negative None in HPA (detected in all 43 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 A05507-2); 2. Fixation: Image fixative and duration unreported (datasheet A05507-2); 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 A05507-2); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet A05507-2); 8. Primary antibody: Rabbit anti-IST1, 2-5 μg/ml (datasheet A05507-2); 9. Primary incubation: Overnight at 4 °C (datasheet A05507-2). Watch for: Fixation: Keep fixation conditions consistent across sections. (standard IHC practice; not target-specific); Caveat: Staining and RNA levels have medium consistency (HPA tissue IHC); Isoform / epitope: 6 isoforms; antibody epitope coverage is unclear (UniProt; datasheet A05507-2); Regulation: RNA has low tissue specificity (HPA tissue RNA). Evidence: UniProt P53990, HPA tissue IHC · Approved, HPA ICC-IF · vesicles., Datasheet A05507-2, PMC10200693. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/IST1/immunohistochemistry-ihc-guide.