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EXTL3 / Exostosin-like 3 · IHC design guide
Design Immunohistochemistry for EXTL3
Plan EXTL3 paraffin IHC using cytoplasmic staining in most tissues as the reference pattern (HPA tissue IHC). Compare high-staining glandular cells with cells reported as unstained, and verify specificity because antibody staining and RNA show low consistency (HPA tissue IHC).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
EXTL3 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 staining in most tissues (HPA tissue IHC) | |
| Staining pattern | Cytoplasmic staining in many glandular cells (HPA tissue IHC) | |
| Antigen retrieval | Tris-EDTA pH 9.0 HIER, 95–98 °C, 20 min (rule: nuclear antigen) | |
| Positive control | Cerebellum+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 fixation conditions consistent across sections. (standard IHC practice; not target-specific) | |
| Caveat | Antibody staining and RNA show low consistency (HPA tissue IHC) | |
| Regulation | Ubiquitous expression (UniProt) | |
| Isoform / epitope | No annotated isoforms; cytoplasmic vs lumenal epitope matters (UniProt) |
Section 1
Recommended EXTL3 IHC & IF Protocols
The catalog antibody’s IHC-P protocol is accompanied by one published EXTL3 IHC protocol using mouse pancreas (PMC4741915).
| Sample | Paraffin-embedded rat kidney tissue; fixative not specified (datasheet A07636) |
| Fixation | Image fixative and duration unreported (datasheet A07636); verify before use. |
| Sectioning | 4–5 µm sections on charged slides (standard) |
| Deparaffinisation | Xylene, graded ethanol series to water (standard) |
| Antigen retrieval | Heat-induced epitope retrieval in Tris-EDTA buffer, pH 9.0, 20 min at 95–98 °C (standard rule: nuclear antigen) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% normal serum of the secondary host, 30 min, room temperature (standard) |
| Primary antibody | Rabbit anti-EXTL3, 1:50-1:200 (datasheet A07636) |
| Primary incubation | Overnight at 4 °C (standard) |
| Detection | HRP-polymer secondary, DAB chromogen 5–10 min (standard) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | EXTL3-positive staining in purkinje cells of cerebellum (HPA tissue IHC: High). HPA tissue profile: Cytoplasmic expression in most tissues. No signal in the no-primary control. |
💡Decision noteStart with Tris-EDTA pH 9.0 at 95–98 °C for 20 min (page antigen-retrieval setting); the published protocol does not specify retrieval (PMC4741915).
Section 2
What Is the Expected EXTL3 Staining Pattern?
EXTL3 is a membrane protein reported in the endoplasmic reticulum, Golgi, cell membrane and, under a stated condition, nucleus (UniProt O43909). In tissue IHC, expect predominantly cytoplasmic staining, especially in selected glandular cells, cholangiocytes and Purkinje cells (HPA tissue IHC). HPA rates the tissue pattern Approved but reports low agreement with RNA data and pending external verification (HPA tissue IHC).
| Cytoplasmic staining in pancreatic exocrine glandular cells, liver cholangiocytes or cerebellar Purkinje cells. | These cell populations have High HPA tissue staining and offer useful positive comparators (HPA tissue IHC). Judge the named cells within their tissue context; the HPA profile describes cytoplasmic expression in most tissues, not uniform staining of every cell (HPA tissue IHC). |
| Predominantly nuclear staining, with little cytoplasmic signal, across an ordinary tissue section. | This differs from the reported tissue IHC profile (HPA tissue IHC). UniProt lists the nucleus and specifies that interaction with REG3A induces nuclear translocation (UniProt O43909). Without evidence of that condition, investigate the staining and controls before calling widespread nuclear signal an EXTL3 pattern (standard IHC practice). |
| Strong staining in adipocytes, bone marrow hematopoietic cells or ovarian follicle cells. | HPA reports EXTL3 as not detected in those cell populations (HPA tissue IHC). An isolated strong result raises concern for antibody cross-reactivity or endogenous chromogenic detection activity; examine reagent controls and tissue morphology (standard IHC practice). HPA's negative observations do not establish absolute absence of EXTL3. |
| Diffuse color across multiple compartments or tissue structures, obscuring individual cells. | A broad deposit cannot be assigned confidently to the cytoplasmic cell pattern reported by HPA (HPA tissue IHC). Check a no-primary control, blocking and chromogen development to identify background or endogenous detection activity (standard IHC practice). Interpret any remaining cell signal against morphology. |
| No staining in pancreatic exocrine glandular cells despite an otherwise readable section. | HPA reports High staining in those cells, so the result warrants a technical review (HPA tissue IHC). Verify that the expected cells are present, then assess the IHC-validated antibody, antigen retrieval and detection controls (standard IHC practice). One negative section cannot overturn a tissue-wide expression claim. |
💡Expected EXTL3 appearanceCall a result consistent when cytoplasmic staining is clear in HPA High cell populations such as pancreatic exocrine glandular cells; widespread nuclear-only color or strong color in HPA-undetected cell populations needs control-based review (HPA tissue IHC; UniProt O43909; standard IHC practice).
| Membrane topology | EXTL3 has one transmembrane segment at residues 31–51, a cytoplasmic N terminus and a lumenal region spanning residues 52–919 (UniProt O43909 topology). Membrane association is compatible with the HPA cytoplasmic tissue appearance; topology alone cannot specify a chromogenic subcellular pattern. |
| Conditional nuclear location | UniProt lists nuclear localisation and links translocation to interaction with REG3A (UniProt O43909). Treat nuclear staining as context dependent; HPA's tissue summary remains cytoplasmic (HPA tissue IHC). |
| Tissue and antibody evidence | HPA lists CAB025387 as IHC Approved, while the tissue profile has low consistency with RNA expression and awaits external verification (HPA antibodies; HPA tissue IHC). Use the named positive and undetected cell populations as comparators, with that limitation in mind. |
| Annotated processing and glycosylation | UniProt annotates one chain spanning residues 1–919, no signal peptide or propeptide, and glycosylation sites at 290, 592 and 790 (UniProt O43909). These annotations do not establish epitope location, antigen retrieval needs or fixation sensitivity. |
| IF/ICC: is a matching pattern established? | HPA gives a membrane subcellular summary but no main location or ICC/IF image-bearing cell lines; its listed antibody has no ICC status (HPA subcellular; HPA antibodies). UniProt reports several locations (UniProt O43909). This evidence does not define an IF/ICC positive-control image or protocol. |
| Situation | Likely cause | Next action |
|---|---|---|
| The expected positive glandular cells are blank. | The cell population may be missing from the section, or the staining workflow may have failed (standard IHC practice); HPA reports High staining in pancreatic exocrine glandular cells (HPA tissue IHC). | Confirm cell identity on the counterstained section and compare a positive tissue control; review the antibody, antigen retrieval and detection steps using the chosen IHC protocol (standard IHC practice). |
| The no-primary control develops color. | Primary-independent signal indicates background from the detection system or tissue activity (standard IHC practice). | Address endogenous detection activity, blocking and chromogen development before scoring EXTL3; repeat the control alongside the test section (standard IHC practice). |
| Color is strongest in adipocytes or marrow hematopoietic cells. | Those cells are not detected in HPA tissue IHC, so cross-reactivity or detection background is plausible (HPA tissue IHC; standard IHC practice). | Inspect morphology and no-primary controls, then compare a HPA High cell population in the same run before assigning specificity (HPA tissue IHC; standard IHC practice). |
| Nuclear staining dominates the section. | HPA's tissue profile is cytoplasmic, although REG3A interaction can induce nuclear translocation (HPA tissue IHC; UniProt O43909). | Check whether the biological context supports that interaction; inspect controls and accompanying cytoplasmic signal before accepting a nuclear interpretation (UniProt O43909; standard IHC practice). |
| Nearly every structure shows diffuse chromogen. | The deposit obscures the cell-resolved cytoplasmic pattern described by HPA and may reflect nonspecific staining or overdevelopment (HPA tissue IHC; standard IHC practice). | Use the no-primary control to locate background, review blocking and chromogen timing, and score only interpretable cells (standard IHC practice). |
| An IF/ICC result seems inconsistent with the IHC slide. | HPA provides a membrane IF summary without an image-bearing cell line or ICC validation status for the listed antibody (HPA subcellular; HPA antibodies). | Evaluate IF/ICC with its own validated controls and guide; use HPA tissue IHC only for the paraffin-section cell pattern (HPA tissue IHC; standard IF/ICC practice). |
Experiment evidence
IHC & IF images showing EXTL3 staining
A07636 · IHCImmunohistochemistry of paraffin-embedded rat kidney using EXTL3 Rabbit pAb at dilution of 1:100 .Perform microwave antigen retrieval with 1
A07636 · IHCImmunohistochemistry of paraffin-embedded mouse kidney using EXTL3 Rabbit pAb at dilution of 1:100 .Perform microwave antigen retrieval with
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000012232-EXTL3/tissue/cerebral+cortex#imid_15174006
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000012232-EXTL3/tissue/colon#imid_15173932
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000012232-EXTL3/tissue/liver#imid_15173917
HPA · PancreasHuman Protein Atlas IHC, Pancreas. Source: https://www.proteinatlas.org/ENSG00000012232-EXTL3/tissue/pancreas#imid_15173884
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for EXTL3 IHC & IF
🧪Run liver first: cholangiocytes should stain (HPA: High in liver cholangiocytes). Use adipose tissue as the negative tissue: adipocytes should show no specific staining (HPA: Not detected in adipocytes); on the liver slide, cells without specific staining should show background-level signal, without assuming every non-cholangiocyte is negative (standard IHC practice; UniProt O43909 tissue specificity: ubiquitous).
Positive control tissue: Cerebellum (Purkinje 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 EXTL3; derive a cell-line control from the positive tissue's cell type (Purkinje cells) and confirm it by RNA or western blot first.
Technical controls: Include a no-primary, secondary-only control, matched nonimmune rabbit polyclonal IgG control, and EXTL3 knockout material or a validated peptide-block control (selected caption: rabbit pAb; standard IHC practice). Block endogenous peroxidase and check for endogenous biotin if using biotin-based detection in liver (standard IHC practice).
⚠️Feasibility: A target-specific fixation window or fixation effect is unreported, and the selected 1:100 paraffin-section caption does not state a fixative (selected SKU A07636 caption). That caption uses microwave antigen retrieval in 10 mM PBS, pH 7.2, but does not establish that retrieval is required (selected SKU A07636 caption). Paraffin IHC has a reported staining condition here; the supplied evidence does not establish whether frozen sections or IF/ICC are easier, and endogenous liver peroxidase can complicate chromogenic interpretation (selected SKU A07636 caption; standard IHC practice).
HPA tissue IHC evidence for EXTL3
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Approved — Low 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 |
|---|---|---|---|---|
| Cerebellum | Purkinje cells | High | Protein (IHC) | HPA → |
| Gallbladder | Glandular cells | High | Protein (IHC) | HPA → |
| Liver | Cholangiocytes | High | Protein (IHC) | HPA → |
| Pancreas | Exocrine glandular cells | High | Protein (IHC) | HPA → |
| Placenta | Decidual 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 → |
| Ovary | Follicle cells | Not detected | Protein (IHC) | HPA → |
| Soft tissue | Chondrocytes | Not detected | Protein (IHC) | HPA → |
| Spleen | Cells in red pulp | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced EXTL3 IHC Tips
Troubleshoot EXTL3 staining in paraffin sections by checking retrieval, compartment, cell identity, and controls before comparing staining intensity.
How should I adjust retrieval when EXTL3 staining is weak?
Start with Tris-EDTA pH 9.0 heat-induced epitope retrieval at 95–98 °C for 20 min (page retrieval rule: nuclear antigen). Run a positive-control section alongside the sample; pancreatic exocrine glandular cells show high staining in the HPA tissue profile, although that profile has low agreement with RNA data (HPA tissue IHC). If staining remains weak, test microwave retrieval in 10 mM PBS at pH 7.2 on an adjacent section, matching the selected A07636 rat-kidney image method (A07636 caption). Keep section thickness, antibody dilution, detection, and development time matched so the retrieval comparison remains interpretable (standard IHC practice).
Could fixation explain weak or uneven EXTL3 staining?
EXTL3-specific fixation sensitivity is unknown: the selected paraffin-section caption does not state a fixative, and the supplied evidence provides no controlled fixation comparison (A07636 caption). Record the actual fixative, fixation duration, and processing history for each specimen before attributing a weak result to EXTL3 loss (standard IHC practice). Compare similarly processed sections with the same retrieval, detection, and counterstain settings; include a positive-control section in each run (standard IHC practice). If one specimen stains unevenly, inspect preservation and staining at its center and edges, then repeat on a better-preserved section before drawing a biological conclusion (standard IHC practice).
Which staining compartments are plausible for EXTL3?
Interpret cytoplasmic staining in tissue sections as plausible, since the HPA profile describes cytoplasmic expression in most tissues (HPA tissue IHC). EXTL3 is also annotated at the endoplasmic reticulum membrane, Golgi apparatus, cell membrane, and nucleus; interaction with REG3A can induce nuclear translocation (UniProt O43909 subcellular annotation). Its single transmembrane segment spans residues 31–51, leaving residues 1–30 cytoplasmic and 52–919 lumenal (UniProt O43909 topology). Record cytoplasmic, membranous, and nuclear signal separately, and confirm a surprising compartment with controls because the location annotation alone does not validate a particular staining pattern (standard IHC practice).
How do topology and processing affect epitope interpretation?
The supplied record lists 0 annotated isoforms and one chain spanning residues 1–919, so an isoform-specific staining claim is unsupported here (UniProt O43909 processing and isoforms). EXTL3 has a cytoplasmic segment at 1–30 and a lumenal segment at 52–919; the antibody epitope is not supplied (UniProt O43909 topology; supplied antibody evidence). Glycosylation is annotated at residues 290, 592, and 790, but its effect on this antibody’s tissue staining is unknown (UniProt O43909 glycosylation; supplied antibody evidence). Obtain the immunogen or epitope specification before assigning a negative section to epitope masking, and compare retrieval conditions on matched sections if signal is weak (standard IHC practice).
How can IF help resolve ambiguous chromogenic staining?
Use IF on a matched section to compare EXTL3 signal with a marker for the expected cell type, then check whether the two signals occur in the same cells (standard IF practice). Choose spectrally separated fluorophores after checking tissue autofluorescence, and include single-stain controls to assess bleed-through (standard IF practice). If the antibody recognizes residues 1–30, access to the cytoplasmic side may require permeabilisation; an epitope within residues 52–919 faces the organelle lumen, but this antibody’s epitope is unspecified (UniProt O43909 topology; supplied antibody evidence). Treat the IF result as an independent comparison: the supplied A07636 image documents paraffin-section IHC, while the HPA subcellular payload lists no ICC/IF images (A07636 caption; HPA subcellular).
How can I reduce diffuse or misleading EXTL3 background?
Run a no-primary control through the same chromogenic detection and counterstain steps to identify signal unrelated to primary-antibody binding (standard IHC practice). Quench endogenous peroxidase before peroxidase-based detection, block nonspecific binding, and compare a small primary-antibody dilution series with identical development times (standard IHC practice). The selected A07636 rat-kidney image used a 1:100 dilution; that image does not establish the best dilution for other specimens (A07636 caption). Check whether diffuse signal persists in the no-primary control or concentrates at section edges, folds, or damaged areas before treating it as EXTL3 expression (standard IHC practice).
How should EXTL3 IHC be scored across samples? ⚠ ANSWER MARKED FOR VERIFICATION
Define the scored compartment and cell population before analysis, then report either an H-score or the percentage of positive cells with the scoring threshold stated (standard IHC practice). For a defined cell population, calculate H-score as 1 × % weak + 2 × % moderate + 3 × % strong, giving a range of 0–300 (standard IHC practice). If cell density is the outcome, report positive cells per mm² of viable tissue and state how total cells or tissue area supplied the denominator (standard IHC practice). Keep retrieval, antibody dilution, chromogen development, imaging, and threshold settings consistent, and score cytoplasmic and nuclear signal separately where both occur (standard IHC practice; UniProt O43909 subcellular annotation).
When is an EXTL3-positive cell convincing rather than artefactual?
A convincing result has reproducible staining in intact cells and the expected compartment, with little corresponding signal in a no-primary control (standard IHC practice). HPA reports high staining in pancreatic exocrine glandular cells and liver cholangiocytes, but its tissue profile has low consistency with RNA data and awaits external verification (HPA tissue IHC). Treat isolated nuclear staining cautiously: nuclear location is annotated, and REG3A interaction can induce translocation, but that does not establish nuclear localisation in a particular section (UniProt O43909 subcellular annotation). Exclude edge effects, necrotic areas, and endogenous-enzyme signal before calling cells positive; compare the proposed pattern with an independently stained section when the result drives a conclusion (standard IHC practice).
Boster reagents
Best EXTL3 / Exostosin-like 3 IHC Antibodies
A07636 has real EXTL3 IHC images from paraffin-embedded rat and mouse kidney; catalog reactivity includes human, mouse and rat (catalog IHC image captions; catalog reactivity).
Real IHC data
Anti-Exostosin-like 3 EXTL3 Antibody
Cat # A07636
A07636 is listed for IHC and shows staining in paraffin-embedded rat kidney at 1:100 (catalog applications; rat kidney image caption). Its second IHC image shows paraffin-embedded mouse kidney at 1:100; human reactivity is listed without a human IHC image (mouse kidney image caption; catalog reactivity; catalog IHC image captions).
Which to pick: Choose A07636 for paraffin-section IHC: its rat and mouse kidney captions specify microwave antigen retrieval in 10 mM PBS, pH 7.2, and the listed IHC dilution range is 1:50–1:200 (catalog IHC image captions; catalog IHC dilution). The captions do not report a fixative (catalog IHC image captions). For cross-species work, its listed reactivity covers human, mouse and rat, though the IHC images document only mouse and rat; no IF/ICC application or image is listed for this SKU (catalog reactivity; catalog applications; catalog IHC and IF image captions).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry O43909 (EXTL3_HUMAN, Exostosin-like 3).
- Human Protein Atlas. EXTL3 tissue IHC expression (reliability: Approved).
- Human Protein Atlas. EXTL3 subcellular location (ICC-IF): Membrane.
- Human Protein Atlas. EXTL3 antibody validation summary (1 antibodies).
- Regenerating islet-derived protein 1 inhibits the activation of islet stellate cells isolated from diabetic mice. Oncotarget 2015 — PMC4741915.
- REG3A/REG3B promotes acinar to ductal metaplasia through binding to EXTL3 and activating the RAS-RAF-MEK-ERK signaling pathway. Communications biology 2021 — PMC8184755.
- The antimicrobial protein REG3A regulates keratinocyte proliferation and differentiation after skin injury. Immunity 2012 — PMC3828049.
- PubMed PMID:9479495 — UniProt-cited evidence.
- PubMed PMID:9473480 — UniProt-cited evidence.
- PubMed PMID:9628581 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for EXTL3 (Exostosin-like 3). Expected localisation Cytoplasmic staining in most tissues (HPA tissue IHC). Antigen retrieval: Tris-EDTA pH 9.0 HIER, 95–98 °C, 20 min (rule: nuclear antigen). Validated IHC antibody: A07636 at 1:50-1:200 (the product's own IHC validation image is shown). Controls (HPA): positive Cerebellum (Purkinje cells); negative Adipose tissue. IHC workflow; specimen preparation unspecified. Protocol steps: 1. Sample: Paraffin-embedded rat kidney tissue; fixative not specified (datasheet A07636); 2. Fixation: Image fixative and duration unreported (datasheet A07636); verify before use.; 3. Sectioning: 4–5 µm sections on charged slides (standard); 4. Deparaffinisation: Xylene, graded ethanol series to water (standard); 5. Antigen retrieval: Heat-induced epitope retrieval in Tris-EDTA buffer, pH 9.0 , 20 min at 95–98 °C…; 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% normal serum of the secondary host, 30 min , room temperature (standard); 8. Primary antibody: Rabbit anti-EXTL3, 1:50-1:200 (datasheet A07636); 9. Primary incubation: Overnight at 4 °C (standard). Watch for: Fixation: Keep fixation conditions consistent across sections. (standard IHC practice; not target-specific); Caveat: Antibody staining and RNA show low consistency (HPA tissue IHC); Isoform / epitope: No annotated isoforms; cytoplasmic vs lumenal epitope matters (UniProt); Regulation: Ubiquitous expression (UniProt). Evidence: UniProt O43909, HPA tissue IHC · Approved, HPA ICC-IF · Membrane, Datasheet A07636, PMC4741915. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/EXTL3/immunohistochemistry-ihc-guide.