HNRNPA1 / Heterogeneous nuclear ribonucleoprotein A1 · IHC design guide

Design Immunohistochemistry for HNRNPA1

Plan chromogenic IHC for HNRNPA1 around the ubiquitous nuclear tissue pattern (HPA tissue IHC). This guide covers section handling, controls and interpretation, including the reported possibility of staining protein from another gene (HPA tissue IHC).

Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use

Immunohistochemistry protocol sheet for HNRNPA1 (IHC for HNRNPA1): expected localisation Nuclear staining in tissue (HPA tissue IHC), antibody A01476, validated IHC image, and IHC protocol steps — Printable **HNRNPA1** IHC protocol sheet — expected localisation Nuclear staining in tissue (HPA tissue IHC), antibody A01476, controls and protocol steps. Open the full HNRNPA1 IHC guide →

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HNRNPA1 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 tissue (HPA tissue IHC)
	Staining pattern	Ubiquitous nuclear staining across cell types (HPA tissue IHC)
	Antigen retrieval	Citrate pH 6 HIER, heat-mediated (datasheet A01476)
	Positive control ⓘ	Adipose tissue+4 more · see all
	Negative control ⓘ	None in HPA (detected in all 45 tissues); use no-primary + isotype controls

Important caveats

Reasons your staining may differ from the expected pattern.

	Fixation	Keep fixation consistent across sections (standard IHC practice; not target-specific)
	Caveat	Staining may include protein from another gene (HPA tissue IHC)
	Regulation	No specific staining regulator annotated (UniProt)
	Isoform / epitope	3 isoforms; check epitope coverage (UniProt)

Section 1

Recommended HNRNPA1 IHC & IF Protocols

The catalog antibody uses citrate pH 6 retrieval (datasheet A01476). One published IHC protocol provides additional section, incubation, and detection details (PMC13126795).

Recommended immunohistochemistry (IHC-P) protocol parameters
Sample	Paraffin-embedded mouse intestine tissues; fixative not specified (datasheet A01476)
Fixation	Image fixative and duration unreported (datasheet A01476); verify before use.
Sectioning	4–5 µm sections on charged slides (standard)
Deparaffinisation	Xylene, graded ethanol series to water (standard)
Antigen retrieval	Heat retrieval: Citrate pH 6, 20 min (datasheet A01476)
Peroxidase block	3% H2O2, 10 min, room temperature (standard)
Blocking	10% goat serum (datasheet A01476)
Primary antibody	Rabbit anti-HNRNPA1, 0.5-1μg/ml (datasheet A01476)
Primary incubation	Overnight at 4 °C (datasheet A01476)
Detection	Streptavidin-biotin complex (SABC), DAB chromogen (datasheet A01476)
Counterstain	Hematoxylin, blue, dehydrate and mount (standard)
Expected result	HNRNPA1-positive staining in adipocytes of adipose tissue (HPA tissue IHC: High). HPA tissue profile: Ubiquitous nuclear expression. No signal in the no-primary control.

💡Decision noteStart with heat-mediated citrate pH 6 retrieval (datasheet A01476); the published protocol confirms retrieval but does not specify its conditions (PMC13126795).

Section 2

What Is the Expected HNRNPA1 Staining Pattern?

HNRNPA1 should appear predominantly in nuclei across many human cell types (HPA: ubiquitous nuclear expression; UniProt P09651: nucleus). Adipocytes, bone marrow hematopoietic cells and bronchial respiratory epithelial cells are examples with high tissue IHC staining (HPA: High). HPA rates the tissue pattern Supported, while cautioning that the staining may detect protein from more than one gene (HPA: reliability description). HNRNPA1 has no transmembrane segment (UniProt P09651: topology).

What am I looking at on my slide?
Strong nuclear staining in cells of a high-staining reference tissue, with cell outlines still discernible.	This fits the reported ubiquitous nuclear pattern; HPA lists high staining in adipocytes, bone marrow hematopoietic cells and bronchial respiratory epithelial cells (HPA: tissue IHC). Compare staining within the same section before judging intensity, because these examples do not define a universal scoring cutoff.
Cytoplasmic staining dominates while nuclei are faint or clear.	Check the stain before calling this the expected tissue result: HPA reports ubiquitous nuclear IHC staining, although UniProt also places HNRNPA1 in the cytoplasm and cytoplasmic mRNP granules (HPA: tissue IHC; UniProt P09651: subcellular location). Predominantly cytoplasmic chromogen alone does not establish a localization shift.
Unexpected cells stain as strongly as the anticipated nuclei.	Review morphology and controls for cross-reactivity or endogenous detection activity (standard IHC practice). HPA cautions that its supported tissue staining may detect protein from more than one gene (HPA: reliability description). Broad nuclear staining by itself is plausible because HPA describes the pattern as ubiquitous.
Brown color spreads through stroma or across cells without clear nuclear boundaries.	Treat this as background until controls and staining distribution support a cellular signal (standard chromogenic IHC practice). A diffuse deposit cannot be scored as HNRNPA1 expression merely because a high-staining tissue was selected; HPA's reported pattern is nuclear (HPA: tissue IHC).
No nuclear staining appears in a reference tissue expected to stain highly.	First suspect an assay or section problem, then review the actual tissue and cell identity (standard IHC practice). HPA reports high staining in several specified cell populations, but supplies no negative tissue list or detection threshold here (HPA: tissue IHC). A blank section alone cannot establish absent HNRNPA1.

💡Expected HNRNPA1 appearanceCall a positive result when crisp nuclear chromogen is evident in the expected cells, especially in a high-staining reference population (HPA: ubiquitous nuclear expression; HPA: High); diffuse tissue color or cytoplasm-only staining without nuclear signal warrants control review (standard IHC practice; HPA: tissue IHC).

How each factor affects the staining
Antibody interpretation	HPA rates tissue IHC Supported and lists IHC Supported status for HPA001609, HPA001666 and CAB010894 (HPA: antibody validation; HPA: tissue reliability). Its caution about detection of protein from more than one gene limits gene-specific conclusions from a positive stain.
Target location and forms	HNRNPA1 has no transmembrane segment, has three annotated isoforms, and includes an N-terminally processed chain beginning at residue 2 (UniProt P09651: topology, isoforms, processing). These annotations alone do not predict which form an unspecified antibody recognizes or how a paraffin section will stain.
IF/ICC: where should fluorescence appear?	Primarily in the nucleoplasm: HPA reports an enhanced nucleoplasmic location in ICC-IF images from its listed cell lines (HPA: subcellular). UniProt also records nuclear–cytoplasmic shuttling and cytoplasmic mRNP granules (UniProt P09651: subcellular location). Interpret that fluorescence on its own guide page.
Detection chemistry	Endogenous enzyme activity or nonspecific reagent binding can mimic chromogenic staining; appropriate detection controls help identify it (standard IHC practice). The supplied HPA and UniProt records do not establish a target-specific endogenous activity or an HNRNPA1 fixation sensitivity.

Why is my staining missing, weak or wrong?
Situation	Likely cause	Next action
No signal in the expected reference cells	The staining run, section or tissue identification may need checking (standard IHC practice).	Verify morphology and controls, then review the catalog antibody's IHC-P instructions for retrieval, dilution and detection. Recheck nuclei in a named high-staining cell population (HPA: tissue IHC); do not infer true absence from this run.
Nuclear signal is weak but background is low	Detection or antibody conditions may be insufficient for the run (standard IHC practice).	Check positive controls and optimize within the antibody's IHC-P instructions, changing one condition at a time (standard IHC practice). HPA's High category identifies useful reference cells but does not supply a required chromogen intensity (HPA: tissue IHC).
Cytoplasmic color exceeds nuclear color	Background, morphology or genuine cytoplasmic localization may contribute (standard IHC practice; UniProt P09651: subcellular location).	Compare intact cells and detection controls. Document the compartment pattern, and avoid scoring a cytoplasm-only result as the expected tissue pattern without supporting evidence (HPA: ubiquitous nuclear expression).
Diffuse color obscures cell boundaries	Nonspecific antibody or detection background may obscure localization (standard IHC practice).	Inspect reagent controls, blocking and washes, then adjust the staining conditions according to the IHC-P instructions (standard IHC practice). Score only interpretable cellular staining; HPA reports a nuclear pattern (HPA: tissue IHC).
Unexpected cell types show crisp nuclear staining	HNRNPA1 is widely expressed, while antibody cross-detection remains a possibility (HPA: ubiquitous nuclear expression; HPA: reliability caution).	Confirm cell identity by morphology and compare an independent, appropriately validated antibody if gene-specific interpretation matters (standard IHC practice). Do not designate an unlisted cell type negative solely because it was not among HPA's examples.
Signal appears in a detection-only control	Endogenous detection activity or reagent background may be present (standard chromogenic IHC practice).	Resolve the control signal using suitable blocking or detection changes before interpreting the specimen (standard IHC practice). A positive control artifact cannot support an HNRNPA1 expression call.

Source: UniProt P09651 Human Protein Atlas tissue Human Protein Atlas subcellular

Experiment evidence

IHC & IF images showing HNRNPA1 staining

IHC analysis of HnRNP A1 using anti-HnRNP A1 antibody (A01476). HnRNP A1 was detected in paraffin-embedded section of mouse intestine tissues. Heat mediated antigen retrieval was performed in citrate buffer (pH6, epitope retrieval solution) for 20 mins. The tissue section was blocked with 10% goat serum. The tissue section was then incubated with 1μg/ml rabbit anti-HnRNP A1 Antibody (A01476) overnight at 4°C. Biotinylated goat anti-rabbit IgG was used as secondary antibody and incubated for 30 minutes at 37°C. The tissue section was developed using Strepavidin-Biotin-Complex (SABC)(Catalog # SA1022) with DAB as the chromogen.

A01476 · IHCIHC analysis of HnRNP A1 using anti-HnRNP A1 antibody (A01476). HnRNP A1 was detected in paraffin-embedded section of mouse intestine tissue

IHC analysis of HnRNP A1 using anti-HnRNP A1 antibody (A01476). HnRNP A1 was detected in paraffin-embedded section of mouse kidney tissues. Heat mediated antigen retrieval was performed in citrate buffer (pH6, epitope retrieval solution) for 20 mins. The tissue section was blocked with 10% goat serum. The tissue section was then incubated with 1μg/ml rabbit anti-HnRNP A1 Antibody (A01476) overnight at 4°C. Biotinylated goat anti-rabbit IgG was used as secondary antibody and incubated for 30 minutes at 37°C. The tissue section was developed using Strepavidin-Biotin-Complex (SABC)(Catalog # SA1022) with DAB as the chromogen.

A01476 · IHCIHC analysis of HnRNP A1 using anti-HnRNP A1 antibody (A01476). HnRNP A1 was detected in paraffin-embedded section of mouse kidney tissues.

IF analysis of HnRNP A1 using anti-HnRNP A1 antibody (A01476). HnRNP A1 was detected in immunocytochemical section of U20S cells. Enzyme antigen retrieval was performed using IHC enzyme antigen retrieval reagent (AR0022) for 15 mins. The cells were blocked with 10% goat serum. And then incubated with 2μg/mL rabbit anti-HnRNP A1 Antibody (A01476) overnight at 4°C. DyLight®550 Conjugated Goat Anti-Rabbit IgG (BA1135) was used as secondary antibody at 1:100 dilution and incubated for 30 minutes at 37°C. The section was counterstained with DAPI. Visualize using a fluorescence microscope and filter sets appropriate for the label used.

A01476 · IFIF analysis of HnRNP A1 using anti-HnRNP A1 antibody (A01476). HnRNP A1 was detected in immunocytochemical section of U20S cells. Enzyme ant

HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000135486-HNRNPA1/tissue/cerebral+cortex#imid_935400

HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000135486-HNRNPA1/tissue/colon#imid_935326

HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000135486-HNRNPA1/tissue/liver#imid_935343

HPA · PancreasHuman Protein Atlas IHC, Pancreas. Source: https://www.proteinatlas.org/ENSG00000135486-HNRNPA1/tissue/pancreas#imid_935286

HPA · ICC-IF A-549Human Protein Atlas immunofluorescence, A-549, antibody HPA005812; green = HNRNPA1, blue = nucleus, red = microtubules.

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Real IHC / IF data behind the staining-pattern expectations in this section.

Sample controls for HNRNPA1 IHC & IF

🧪Run adipose tissue first: adipocytes should show predominantly nuclear staining (HPA: High in adipocytes; HPA: nucleoplasm enhanced). HPA detects HNRNPA1 in all 45 scored tissues and lists no negative tissue, so use no-primary and isotype controls; no cell population on the positive slide is established as an internal biological negative (HPA: no negative rows).

Positive control tissue: Adipose tissue (Adipocytes, HPA High)

Negative control tissue: None in HPA: HNRNPA1 is detected in all 45 scored tissues. Use a no-primary (secondary-only) and an isotype control instead.

ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show HNRNPA1 in A-549, PC-3, U2OS, Rh30, SH-SY5Y, Hep-G2, REH, with annotated localisation: Nucleoplasm (enhanced) (HPA subcellular).

Technical controls: Include a no-primary, secondary-only slide and a concentration-matched rabbit IgG isotype control matched to the primary antibody’s clonality; use HNRNPA1-knockout tissue as a biological negative if available (caption: rabbit primary antibody; standard IHC practice). For adipose tissue, block endogenous peroxidase before DAB detection and check background from the biotin-based detection system (caption: biotinylated secondary, streptavidin–biotin complex and DAB; standard IHC practice).

⚠️Feasibility: A target-specific fixation window or fixation effect is unreported, and the selected A01476 paraffin-section caption does not state the fixative (caption: fixative unreported). The demonstrated IHC procedure used citrate retrieval at pH 6 for 20 minutes; whether HNRNPA1 staining depends on retrieval has not been established by a matched comparison (caption: citrate retrieval). Frozen-section suitability and relative ease of IF are unreported; in adipose tissue, lipid vacuoles can leave little cytoplasm to assess, so judge staining in intact nuclei (HPA: High in adipocytes; standard histology practice).

HPA tissue IHC evidence for HNRNPA1

Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Supported — High consistency between antibody staining and RNA expression data. Caution, targets protein from more than one gene.). Rows are taken directly from the HPA tissue chart — click any row's HPA link to view the source.

Positive expression · recommended positive controls

Tissue	Cell type	Level	Evidence	Source
Adipose tissue	Adipocytes	High	Protein (IHC)	HPA →
Adrenal gland	Glandular cells	High	Protein (IHC)	HPA →
Appendix	Glandular cells	High	Protein (IHC)	HPA →
Bone marrow	Hematopoietic cells	High	Protein (IHC)	HPA →
Breast	Glandular cells	High	Protein (IHC)	HPA →

Undetected expression · recommended negative controls

Tissue	Cell type	Level	Evidence	Source
None in HPA: HNRNPA1 is detected in all 45 scored tissues. Use a no-primary (secondary-only) and an isotype control instead.

Section 3

Advanced HNRNPA1 IHC Tips

Troubleshoot HNRNPA1 staining in paraffin sections by checking retrieval, nuclear localisation, antibody specificity and scoring controls before interpreting chromogenic signal.

What retrieval should I try when HNRNPA1 nuclear staining is weak?

Use heat-mediated retrieval in citrate buffer at pH 6 first (datasheet A01476). The selected paraffin-section example used 20 minutes of citrate retrieval before staining mouse intestine, so keep that condition as the initial reference while checking whether the heating and cooling steps were consistent across slides (caption A01476; standard IHC practice). If signal remains weak, vary retrieval time cautiously on matched sections and compare nuclear staining with tissue damage and background (standard IHC practice; HPA: ubiquitous nuclear expression). A different buffer or pH is a fallback to evaluate only after the documented citrate condition, with matched controls and the same detection settings (datasheet A01476; standard IHC practice).

Could fixation explain weak or uneven HNRNPA1 staining?

Target-specific sensitivity of HNRNPA1 to fixation is unknown from the supplied evidence; the selected paraffin-section caption does not state a fixative (caption A01476). Record the fixative and fixation duration for each specimen, then compare similarly processed sections before attributing differences to antigen abundance (standard IHC practice). If nuclear signal varies between the centre and edge of a specimen, assess fixation uniformity, section quality and retrieval consistency together rather than assigning a target-specific cause (standard IHC practice; HPA: ubiquitous nuclear expression). Keep section thickness, retrieval and chromogenic development consistent during that comparison so staining differences remain interpretable (standard IHC practice).

Should I accept predominantly cytoplasmic HNRNPA1 staining in paraffin sections?

Expect predominantly nuclear staining across many cell types because tissue IHC shows ubiquitous nuclear expression and subcellular imaging places HNRNPA1 in the nucleoplasm (HPA: tissue IHC profile; HPA: nucleoplasm enhanced). Cytoplasmic signal is biologically possible: HNRNPA1 shuttles with mRNA and can occur in cytoplasmic mRNP granules (UniProt P09651: subcellular location). Score nuclear and cytoplasmic staining separately, and compare the pattern with adjacent intact cells and a negative detection control before calling redistribution (standard IHC practice). Diffuse cytoplasmic chromogen without convincing nuclear signal warrants checks for background, tissue preservation and antibody specificity rather than an immediate biological interpretation (HPA: tissue IHC profile; standard IHC practice).

Can this stain distinguish HNRNPA1 isoforms or epitope changes?

Do not assign a stained cell to a particular isoform without documented epitope coverage: the record lists 3 isoforms, A1-B, A1-A and 2 (UniProt P09651: isoforms). HNRNPA1 also contains 2 RNA recognition motifs at residues 14–97 and 105–184, alongside annotated modified residues that could matter if they overlap a particular antibody epitope (UniProt P09651: domains and modified residues). Check the catalog antibody’s stated immunogen or epitope against isoform sequences before comparing staining across specimens (standard IHC practice). Interpret an altered IHC pattern as altered detectable antigen until isoform-specific reagents or independent evidence support a narrower claim (standard IHC practice).

How should I plan an IF follow-up to the chromogenic IHC result?

For an IF follow-up, multiplex HNRNPA1 with a glandular-cell marker such as pan-cytokeratin in appendix sections, where glandular cells show high tissue IHC staining (HPA: high in appendix glandular cells; standard IF practice). Include a nuclear counterstain and assess nucleoplasmic signal within marker-positive cells, while recording cytoplasmic signal separately because HNRNPA1 can shuttle (HPA: nucleoplasm enhanced; UniProt P09651: subcellular location). Select a spectrally separated, preferably far-red fluorophore after checking tissue autofluorescence with an unstained control (standard IF practice). Optimise permeabilisation for access to the nuclear epitope; HNRNPA1 has no transmembrane segment, so a membrane-sided epitope assignment is unsupported (UniProt P09651: topology; standard IF practice).

How can I reduce diffuse brown staining without losing nuclear signal?

First compare stained sections with a no-primary control to identify detection-system or tissue-derived brown signal (standard IHC practice). In the selected paraffin-section example, blocking used 10% goat serum, followed by a biotinylated secondary, avidin–biotin detection and DAB; those are documented conditions for A01476, not proof that every specimen needs them (caption A01476). Check peroxidase blocking and, when using avidin–biotin detection, assess endogenous biotin as possible sources of background (standard IHC practice). Titrate primary antibody and chromogen development on matched sections, preserving discrete nuclear staining as the readout because widespread nuclear expression is expected (HPA: tissue IHC profile; standard IHC practice).

What should I measure when HNRNPA1 stains most nuclei? ⚠ ANSWER MARKED FOR VERIFICATION

Score the proportion of positive nuclei and their intensity within a defined cell population, then calculate an H-score if the study needs a combined measure (HPA: ubiquitous nuclear expression; standard IHC practice). Normalise positive nuclei to all evaluable nuclei of that same population, rather than to total tissue area when cellular composition differs between sections (standard IHC practice). If cytoplasmic redistribution is the question, report the cytoplasmic-positive fraction separately from nuclear intensity and apply one threshold across matched slides (UniProt P09651: nuclear–cytoplasmic shuttling; standard IHC practice). Exclude folds, necrotic areas and section edges from scoring, and document the region selection and chromogen threshold (standard IHC practice).

When is an unexpected HNRNPA1 staining pattern likely artefactual?

Treat crisp nuclear staining in intact cells as the reference pattern, since tissue IHC reports ubiquitous nuclear expression and subcellular imaging places HNRNPA1 in the nucleoplasm (HPA: tissue IHC profile; HPA: nucleoplasm enhanced). Cytoplasmic staining can be plausible because HNRNPA1 shuttles and occurs in cytoplasmic mRNP granules, but it needs reproducible cellular boundaries and a convincing control comparison (UniProt P09651: subcellular location; standard IHC practice). Review unexpected cell populations against tissue morphology and staining controls before assigning biological specificity (standard IHC practice). Signal confined to edges, necrotic regions or endogenous enzyme-rich areas is suspect, particularly when a no-primary control shows similar chromogen deposition (standard IHC practice).

Boster reagents

Best HNRNPA1 / Heterogeneous nuclear ribonucleoprotein A1 IHC Antibodies

A01476 has IHC images from human, mouse and rat paraffin sections and IF images from human and mouse sections and cultured cells (catalog image captions). M01476 lists IHC and IF applications (catalog).

Real IHC data

Anti-HnRNP A1/HNRNPA1 Antibody ®

Cat # A01476

View product →

A01476 will render with its own paraffin-section IHC figure; additional captions document human, mouse and rat IHC, plus human and mouse IF and cultured-cell IF/ICC (A01476 image captions). M01476 will render with IHC and IF listed for human, mouse and rat, but has no IHC or IF image captions in the supplied catalog (M01476 catalog).

Which to pick: Choose A01476 for tissue IHC: its figure documents mouse intestine paraffin sections with citrate retrieval at pH 6 for 20 minutes and antibody at 1 μg/ml (A01476 IHC figure caption); the fixative is unreported (A01476 IHC figure caption). For IF/ICC, A01476 has image captions for both applications, while M01476 is a rabbit monoclonal with IF/ICC listed but no supplied image captions (A01476 IF image captions; M01476 catalog). For cross-species tissue IHC, A01476 has documented human, mouse and rat images; M01476 lists all three species without supplied IHC images (A01476 IHC image captions; M01476 catalog).

Each figure is that product's own IHC / IF validation image from its datasheet.

References

UniProt Consortium. UniProt entry P09651 (ROA1_HUMAN, Heterogeneous nuclear ribonucleoprotein A1).
Human Protein Atlas. HNRNPA1 tissue IHC expression (reliability: Supported).
Human Protein Atlas. HNRNPA1 subcellular location (ICC-IF): Localized to the nucleoplasm..
Human Protein Atlas. HNRNPA1 antibody validation summary (6 antibodies).
hnRNPA1-SF3B3 interaction drives radioresistance in oral squamous cell carcinoma by modulating MARF1 alternative splicing isoforms. Journal of experimental & clinical cancer research : CR 2026 — PMC13126795.
iTRAQ-based proteomic analysis of the molecular mechanisms and downstream effects of fatty acid synthase in osteosarcoma cells. Journal of clinical laboratory analysis 2021 — PMC7957979.
Clinical heterogeneity in a family with flail arm syndrome and review of hnRNPA1-related spectrum. Annals of clinical and translational neurology 2022 — PMC9735363.
Spatial protein expression patterns across pathologically-associated fibers revealed molecular specialization in inclusion body myositis. Cell communication and signaling : CCS 2026 — PMC13032386.
PubMed PMID:2760922 — UniProt-cited evidence.
PubMed PMID:2836799 — UniProt-cited evidence.
PubMed PMID:14702039 — UniProt-cited evidence.