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FMR1 / Fragile X messenger ribonucleoprotein 1 · IHC design guide
Design Immunohistochemistry for FMR1
Plan FMR1 chromogenic IHC in paraffin sections around its cytoplasmic tissue pattern, with distinct staining in neuronal cells and spermatogonia (HPA tissue IHC). Use the guide to choose controls, assess cell types and interpret staining with the antibody’s epitope coverage in mind (UniProt).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
FMR1 Immunohistochemistry Experimental Design Guide
Expected localisation, validated protocols, controls and antibodies — the at-a-glance facts below, then the full design guide.
Must know before staining
| Expected localisation | Cytoplasmic tissue staining (HPA tissue IHC) | |
| Staining pattern | Cytoplasmic staining, distinct in neurons and spermatogonia (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet PB9703) | |
| Positive control | Cerebellum+4 more · see all | |
| Negative control | Adipose tissue |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Keep fixation consistent across sections. (standard IHC practice; not target-specific) | |
| Caveat | Cortical glia can also stain strongly (HPA tissue IHC) | |
| Regulation | Staining varies by cell type (HPA tissue IHC) | |
| Isoform / epitope | 11 isoforms; verify epitope coverage (UniProt) |
Section 1
Recommended FMR1 IHC & IF Protocols
The catalog antibody protocol uses EDTA pH 8.0 retrieval (datasheet: PB9703). The published IHC protocols below describe FMR1 staining in gastric cancer tissue (PMC13006672; PMC12581516).
| Sample | Paraffin-embedded human seminoma testis tissue; fixative not specified (datasheet PB9703) |
| Fixation | Image fixative and duration unreported (datasheet PB9703); 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 PB9703); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet PB9703) |
| Primary antibody | Rabbit anti-FMR1, 2-5 μg/ml (datasheet PB9703) |
| Primary incubation | Overnight at 4 °C (datasheet PB9703) |
| Detection | HRP-conjugated secondary, DAB chromogen (datasheet PB9703) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | FMR1-positive staining in cells in molecular layer of cerebellum (HPA tissue IHC: High). HPA tissue profile: Cytoplasmic expression in all tissues. Distinct expression in neuronal cells and in spermatogonia in seminiferous ducts. No signal in the no-primary control. |
💡Decision noteStart with heat-mediated EDTA pH 8.0 retrieval for the catalog antibody (datasheet: PB9703); citrate retrieval is a published alternative for gastric cancer sections (PMC13006672).
Section 2
What Is the Expected FMR1 Staining Pattern?
FMR1 staining should be predominantly cytoplasmic in paraffin sections (HPA tissue IHC: cytoplasmic expression across tissues; HPA: Approved, with medium consistency between antibody staining and RNA expression). Look for distinct staining in hippocampal neuronal cells and testicular spermatogonia (HPA tissue IHC). FMR1 has no transmembrane segment, although UniProt also describes nuclear and neuronal process localisation (UniProt Q06787: subcellular location and topology).
| Cytoplasmic staining is clear in hippocampal neurons; nearby cells vary in intensity (HPA: High in hippocampal neuronal cells). | This fits the reported positive pattern (HPA tissue IHC). Judge the signal in identified cells, since HPA reports cytoplasmic expression across tissues and different staining levels among cell types (HPA tissue IHC). |
| The strongest signal is nuclear, with little cytoplasmic staining. | Recheck localisation against the predominant cytoplasmic tissue pattern (HPA tissue IHC). Nuclear FMR1 is described, so nuclear signal alone cannot prove an artefact; an isolated strong nuclear pattern warrants review of controls and detection background (UniProt Q06787: subcellular location; general IHC practice). |
| Adipocytes stain strongly while an expected positive population is weak. | Treat this as a specificity warning, since adipocytes were not detected in the HPA tissue IHC record (HPA: Not detected in adipocytes). Cross-reactivity or endogenous detection activity are possible explanations to investigate, rather than a diagnosis from one slide (general IHC practice). |
| Colour spreads evenly across tissue, empty spaces, or several unrelated cell types. | A diffuse deposit does not establish cellular FMR1 localisation (general IHC practice). Check background with an appropriate primary-omission control and inspect blocking, washes, chromogen development, and tissue-associated endogenous activity (general IHC practice). |
| No stain appears in hippocampal neuronal cells or another documented high-staining population (HPA tissue IHC). | An uninformative negative result can reflect failed staining or detection, so first verify an on-slide or same-run positive control (general IHC practice). HPA's Approved tissue profile has medium RNA–staining consistency; its reported level is a guide, not a guarantee for every specimen (HPA tissue IHC). |
💡Expected FMR1 appearanceCall a slide positive when identifiable cells show predominantly cytoplasmic signal, especially hippocampal neurons or spermatogonia, with strong neuronal staining supported in hippocampus; isolated diffuse deposit or strong adipocyte staining is suspect (HPA tissue IHC; general IHC practice).
| Which cells anchor interpretation? | HPA reports High staining in hippocampal neuronal cells, cerebral cortex glia, kidney tubule cells, and lung macrophages, among other populations; adipocytes are Not detected (HPA tissue IHC). Compare like cell types within the specimen rather than assigning one expected intensity to an entire organ (general IHC practice). |
| What compartment should be scored? | The tissue profile is cytoplasmic, while UniProt also lists perikaryon, neurites, synaptic sites, nucleus, and nucleolus (HPA tissue IHC; UniProt Q06787: subcellular location). Tissue IHC does not by itself resolve every listed fine structure, so score the visible cellular compartment at the section's resolution (general IHC practice). |
| How firm is the tissue evidence? | The HPA tissue IHC reliability is Approved, with medium consistency between staining and RNA expression (HPA tissue IHC). Listed antibodies HPA050118, HPA056084, and CAB012444 are individually IHC Approved; the supplied record does not assign IHC Enhanced status to this target (HPA antibodies). |
| Do isoforms or processing predict a different stain? | UniProt lists 11 isoforms, one chain spanning residues 1–632, and no signal peptide, propeptide, or transmembrane segment (UniProt Q06787: isoforms, processing, topology). The supplied data give no antibody epitope, so they cannot predict which isoforms a given antibody detects or a different pattern after antigen retrieval. |
| Can IF/ICC help check localisation? | Yes, as a separate imaging comparison: HPA ICC-IF reports cytosol as the enhanced main location and lists A-431, U-251MG, U2OS, and NIH 3T3 images (HPA subcellular ICC-IF). That cell-image result supports a cytosolic expectation but does not establish the staining intensity of a paraffin tissue section (HPA subcellular ICC-IF; general IHC practice). |
| Situation | Likely cause | Next action |
|---|---|---|
| Expected cytoplasmic cells are negative. | The staining run, detection, or control may have failed; absence of signal alone does not establish absent FMR1 (general IHC practice). | Check a same-run positive population, antibody and detection reagents, and the recorded antigen-retrieval conditions (general IHC practice). HPA reports High staining in hippocampal neuronal cells (HPA tissue IHC). |
| The slide is dominated by nuclear colour. | Background or misassigned compartment is possible, while nuclear localisation remains biologically described (UniProt Q06787: subcellular location; general IHC practice). | Compare the primary-omission control and inspect cytoplasm in identifiable positive cells before calling the pattern specific (general IHC practice; HPA tissue IHC: cytoplasmic expression). |
| Adipocytes or empty spaces carry conspicuous colour. | The distribution conflicts with the reported undetected adipocytes and cellular cytoplasmic pattern; nonspecific deposit is possible (HPA tissue IHC; general IHC practice). | Review the primary-omission control, blocking and wash steps, and chromogen development; score signal only where it belongs to identifiable cells (general IHC practice). |
| Lung macrophages appear intensely coloured alongside broad tissue background. | Macrophages are a documented High population, but surrounding diffuse colour can obscure whether their staining is specific (HPA: High in lung macrophages; general IHC practice). | Assess macrophage cytoplasm separately from extracellular colour and compare the background control on the same run (general IHC practice). |
| A low-staining population is used as the sole negative control. | Low is not equivalent to Not detected: HPA lists Low hepatocytes, cardiomyocytes, and several other populations (HPA tissue IHC). | Use the reported undetected adipocyte population as a pattern reference and include technical controls when assessing background (HPA: Not detected in adipocytes; general IHC practice). |
| Different antibody runs give different cell or compartment patterns. | The listed antibodies have individual IHC Approved status, and the supplied evidence does not establish identical epitopes or isoform coverage (HPA antibodies; UniProt Q06787: isoforms). | Compare matched sections and controls, record the antibody used, and avoid treating one divergent pattern as proof of a new FMR1 location (general IHC practice). |
Experiment evidence
IHC & IF images showing FMR1 staining
PB9703 · IHCIHC analysis of FMRP/FMR1 using anti-FMRP/FMR1 antibody (PB9703). FMRP/FMR1 was detected in a paraffin-embedded section of human seminoma te
PB9703 · IFIF analysis of FMRP/FMR1 using anti-FMRP/FMR1 antibody (PB9703). FMRP/FMR1 was detected in an immunocytochemical section of Hela cells. Enzy
A00192 · IHCImmunohistochemistry of FMR1 in human brain tissue with FMR1 antibody at 2.5 μg/mL.
A00192 · IFImmunofluorescence of FMR1 in human brain tissue with FMR1 antibody at 20 μg/mL.
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000102081-FMR1/tissue/cerebral+cortex#imid_16719875
HPA · Thyroid glandHuman Protein Atlas IHC, Thyroid gland. Source: https://www.proteinatlas.org/ENSG00000102081-FMR1/tissue/thyroid+gland#imid_16719819
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000102081-FMR1/tissue/colon#imid_16719809
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000102081-FMR1/tissue/liver#imid_16719802
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody CAB012444; green = FMR1, blue = nucleus, red = microtubules.
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody CAB012444; green = FMR1, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for FMR1 IHC & IF
🧪Run hippocampus first and expect staining in neuronal cells (HPA: High in hippocampal neuronal cells). Use adipose tissue as the negative comparator, focusing on adipocytes (HPA: Not detected in adipocytes); on the hippocampal slide, cells without specific staining can show local background, but the supplied HPA row does not identify a confirmed negative cell type there (HPA: hippocampal neuronal cells High).
Positive control tissue: Cerebellum (Cells in molecular layer, HPA High)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show FMR1 in A-431, U-251MG, U2OS, NIH 3T3, with annotated localisation: Cytosol (enhanced) (HPA subcellular).
Technical controls: Include a no-primary, secondary-only control and a concentration-matched rabbit IgG isotype control alongside a validated FMR1 knockout specimen as a biological negative (PB9703 tissue-IHC caption: rabbit primary antibody; standard IHC practice). Block endogenous peroxidase and compare any brown hippocampal pigment with the no-primary section before scoring DAB staining (PB9703 tissue-IHC caption: HRP/DAB detection; standard IHC practice).
⚠️Feasibility: A target-specific fixation window or fixation effect is unreported, and the selected PB9703 tissue-IHC caption does not state the fixative (PB9703 tissue-IHC caption). Heat retrieval in EDTA at pH 8.0 is documented for the selected antibody, but retrieval dependence is unreported; the supplied evidence does not establish frozen sections or IF as easier than paraffin-section IHC (PB9703 tissue-IHC caption; HPA: cytosol in ICC-IF). In hippocampus, inspect pigment before assigning granular DAB staining to FMR1 (HPA: hippocampal neuronal cells High; standard IHC practice).
HPA tissue IHC evidence for FMR1
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 |
|---|---|---|---|---|
| Cerebellum | Cells in molecular layer | High | Protein (IHC) | HPA → |
| Cerebral cortex | Glial cells | High | Protein (IHC) | HPA → |
| Epididymis | Glandular cells | High | Protein (IHC) | HPA → |
| Fallopian tube | Glandular cells | High | Protein (IHC) | HPA → |
| Hippocampus | Neuronal cells | High | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Adipose tissue | Adipocytes | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced FMR1 IHC Tips
Troubleshoot FMR1 staining in paraffin section IHC by checking retrieval, cell identity and subcellular pattern before comparing signal intensity (datasheet PB9703; HPA tissue IHC; UniProt Q06787).
What should I change when FMR1 staining is weak after antigen retrieval?
Start with heat mediated antigen retrieval in EDTA at pH 8.0 for paraffin sections (datasheet PB9703). The catalog antibody produced tissue staining after this retrieval, followed by 2 μg/ml primary antibody overnight at 4°C (datasheet PB9703). If staining remains weak, vary heating time in small increments while keeping buffer, antibody concentration and detection conditions constant (standard IHC practice). Compare each trial with an expected positive cell population, such as hippocampal neuronal cells, and inspect tissue integrity alongside signal (HPA tissue IHC; standard IHC practice). Excess heating can damage section morphology and make apparent gains in staining difficult to interpret (standard IHC practice).
Could fixation explain weak or uneven FMR1 staining?
The catalog image identifies a paraffin section but does not state its fixative, so target specific fixation sensitivity is unknown (datasheet PB9703). Record the fixative, fixation duration and time before processing for every section being compared (standard IHC practice). When staining varies, compare sections processed together using the same EDTA retrieval at pH 8.0 and the same 2 μg/ml primary concentration (datasheet PB9703; standard IHC practice). Assess preservation and staining in an expected positive cell population before attributing a difference to FMR1 abundance (HPA tissue IHC; standard IHC practice). Neither tissue staining patterns nor protein features establish how this target responds to a particular fixative (HPA tissue IHC; UniProt Q06787).
Where should convincing FMR1 staining appear in tissue sections?
Look first for cytoplasmic staining: tissue IHC shows cytoplasmic expression across tissues, and subcellular imaging identifies the cytosol as the main location (HPA tissue IHC; HPA subcellular). FMR1 can also occupy perinuclear regions, neuronal projections and cytoplasmic ribonucleoprotein granules, so fine signal outside the soma can be plausible (UniProt Q06787 subcellular). Nuclear localisation is reported, but isolated strong nuclear DAB staining should be checked against controls and cell identity before interpretation (UniProt Q06787 subcellular; standard IHC practice). In hippocampus, assess neuronal cells; in cerebellum, assess cells in the molecular layer (HPA tissue IHC). Use the counterstain to distinguish intracellular signal from pigment or extracellular deposit (standard IHC practice).
How do I investigate an unexpected FMR1 staining pattern when the epitope is unspecified?
The supplied catalog caption does not identify the antibody epitope, so staining cannot be assigned to a particular FMR1 isoform (datasheet PB9703). FMR1 has 11 listed isoforms, and its mapped features include KH domains at residues 222–251 and 285–314 (UniProt Q06787). Document the antibody identifier and request an epitope map before interpreting differences among specimens as isoform specific (datasheet PB9703; standard IHC practice). Reported phosphorylation sites include serines 337, 370 and 460, but their effect on this antibody’s staining is unestablished (UniProt Q06787; datasheet PB9703). If a pattern is unexpected, compare an independently mapped antibody and appropriate negative controls under matched processing conditions (standard IHC practice).
How can I check FMR1 localisation by multiplex IF?
Multiplex FMR1 with a marker identifying the expected cell population, such as neuronal cells in hippocampus, and include single stain controls (HPA tissue IHC; standard IF practice). Choose a fluorophore channel with low background in the specimen and inspect unstained tissue for autofluorescence before assigning puncta to FMR1 (standard IF practice). FMR1 is reported in the cytosol and neuronal processes and has no transmembrane segment; permeabilise cells when testing an intracellular epitope (HPA subcellular; UniProt Q06787 topology; standard IF practice). Optimise permeabilisation against morphology and signal, since the catalog tissue IHC caption does not establish an IF permeabilisation condition (datasheet PB9703; standard IF practice). Check channel bleed through and cell boundaries before claiming colocalisation (standard IF practice).
What should I check when DAB background obscures FMR1 staining?
First compare a no primary control with the stained section to distinguish detection background from primary antibody signal (standard IHC practice). The catalog tissue example used 10% goat serum block, 2 μg/ml primary overnight at 4°C, and an HRP and DAB detection workflow (datasheet PB9703). If background is diffuse, review blocking, washing and primary concentration while changing one condition at a time (standard IHC practice). Include a peroxidase blocking step and examine the no primary control for residual endogenous enzyme activity (standard chromogenic IHC practice). Judge improvement by retained intracellular staining in expected positive cells, not by a darker overall section (HPA tissue IHC; standard IHC practice).
How should I quantify FMR1 staining across paraffin sections? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and region before scoring, since FMR1 staining differs among cell types within tissues (HPA tissue IHC; standard IHC practice). An H score can combine the percentage of cells at each intensity from 0 to 3; alternatively, report percent positive cells or positive cell density per mm² (standard IHC practice). Normalise counts to the number of eligible cells or sampled tissue area, and keep section thickness, illumination and DAB development consistent (standard IHC practice). Score cytoplasmic signal separately from nuclear or extracellular colour because cytoplasmic staining is the tissue IHC reference pattern (HPA tissue IHC; standard IHC practice). Record background thresholds using controls processed alongside the study sections (standard IHC practice).
How do I distinguish true FMR1 signal from staining artefact?
A plausible positive result is intracellular, predominantly cytoplasmic staining in an expected cell population, such as hippocampal neuronal cells or seminiferous duct spermatogonia (HPA tissue IHC). FMR1 can also localise to neuronal projections and, in some contexts, the nucleus, so assess those patterns with cell identity and controls rather than location alone (UniProt Q06787 subcellular; standard IHC practice). Be cautious with staining confined to section edges, necrotic areas or extracellular deposits, which can reflect processing or detection artefacts (standard IHC practice). Compare suspect DAB colour with a no primary control and confirm adequate peroxidase blocking before calling it FMR1 (standard chromogenic IHC practice). Tissue IHC evidence has medium consistency with RNA expression, so avoid inferring protein abundance from RNA alone (HPA tissue IHC).
Boster reagents
Best FMR1 / Fragile X messenger ribonucleoprotein 1 IHC Antibodies
Anti-FMR1 antibodies have IHC images from human seminoma testis paraffin sections and human brain tissue, plus IF images from human brain tissue and HeLa cells (catalog image captions).
Real IHC data
Anti-FMRP/FMR1 Antibody ®
Cat # PB9703
Real IHC data
Anti-FMR1 Antibody
Cat # A00192
PB9703 has an IHC image from a human seminoma testis paraffin section and an IF/ICC image from HeLa cells (PB9703 image captions). A00192 has IHC and IF images from human brain tissue (A00192 image captions).
Which to pick: Choose PB9703 for paraffin section IHC: its caption documents EDTA retrieval and DAB detection, but does not report the fixative (PB9703 IHC caption). For IF, A00192 has a human brain tissue image; for ICC/IF, PB9703 has a HeLa cell image (A00192 and PB9703 IF captions). Both list Human, Mouse, and Rat reactivity, but their IHC images document human samples only (catalog reactivity; IHC image captions).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry Q06787 (FMR1_HUMAN, Fragile X messenger ribonucleoprotein 1).
- Human Protein Atlas. FMR1 tissue IHC expression (reliability: Approved).
- Human Protein Atlas. FMR1 subcellular location (ICC-IF): Localized to the cytosol..
- Human Protein Atlas. FMR1 antibody validation summary (3 antibodies).
- AAV-delivered diacylglycerol kinase DGKk achieves long-term rescue of fragile X syndrome mouse model. EMBO molecular medicine 2022 — PMC9081908.
- Integrative single-cell, spatial, and bulk transcriptomics reveal an FMR1-FTO axis linked to the immune-excluded phenotype in gastric cancer. Frontiers in immunology 2026 — PMC13006672.
- Fragile X mental retardation 1 gene FMR1 promotes proliferation, migration, and invasion of gastric cancer cells via c-MYC. Journal of translational medicine 2025 — PMC12581516.
- EZH2 inhibition reactivates epigenetically silenced FMR1 and normalizes molecular and electrophysiological abnormalities in fragile X syndrome neurons. Frontiers in neuroscience 2024 — PMC10915284.
- PubMed PMID:1710175 — UniProt-cited evidence.
- PubMed PMID:8504300 — UniProt-cited evidence.
- PubMed PMID:8401531 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for FMR1 (Fragile X messenger ribonucleoprotein 1). Expected localisation Cytoplasmic tissue staining (HPA tissue IHC). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet PB9703). Validated IHC antibody: PB9703 at 2-5 μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Cerebellum (Cells in molecular layer); negative Adipose tissue. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human seminoma testis tissue; fixative not specified (datasheet PB9703); 2. Fixation: Image fixative and duration unreported (datasheet PB9703); 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 PB9703); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet PB9703); 8. Primary antibody: Rabbit anti-FMR1, 2-5 μg/ml (datasheet PB9703); 9. Primary incubation: Overnight at 4 °C (datasheet PB9703). Watch for: Fixation: Keep fixation consistent across sections. (standard IHC practice; not target-specific); Caveat: Cortical glia can also stain strongly (HPA tissue IHC); Isoform / epitope: 11 isoforms; verify epitope coverage (UniProt); Regulation: Staining varies by cell type (HPA tissue IHC). Evidence: UniProt Q06787, HPA tissue IHC · Approved, HPA ICC-IF · cytosol., Datasheet PB9703, PMC13006672, PMC12581516. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/FMR1/immunohistochemistry-ihc-guide.