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NOS1 / Nitric oxide synthase 1 · IHC design guide
Design Immunohistochemistry for NOS1
Plan chromogenic NOS1 IHC on paraffin sections with the catalog antibody at 0.5–1 μg/ml (datasheet). Use caudate neurons as a positive reference and assess cytoplasmic staining in a subset of neurons or renal distal tubules (HPA tissue IHC).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
NOS1 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 | Cytoplasm in neurons and renal distal tubules (HPA tissue IHC) | |
| Staining pattern | A subset of neurons and renal distal tubules stains cytoplasm (HPA tissue IHC) | |
| Antigen retrieval | Citrate pH 6.0 HIER, 95–98 °C, 20 min (rule: cytoplasmic / membrane antigen) | |
| Positive control | Caudate+4 more · see all | |
| Negative control | Adipose tissue+4 more · see all |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Matched tissue-IHC evidence does not establish the fixation claim. Validate the specimen-specific method before use. (selected-SKU IHC image PA1329) | |
| Caveat | Muscle RNA enrichment may exceed observed myocyte staining (HPA tissue IHC/RNA) | |
| Regulation | Isoform 3 is testis restricted (UniProt) | |
| Isoform / epitope | 5 isoforms; intracellular access matters; epitope coverage unknown (UniProt; datasheet) |
Section 1
Recommended NOS1 IHC & IF Protocols
The catalog antibody protocol is accompanied by published NOS1 IHC methods for paraffin sections of renal tumours and lung cancer specimens (PMC2409527; PMC5882435).
| Sample | Tissue sections; selected-image fixative not specified (standard IHC workflow) |
| Fixation | Image fixative and duration unreported (datasheet PA1329); 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 citrate buffer, pH 6.0, 20 min at 95–98 °C (standard rule: cytoplasmic / membrane 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-NOS1, 0.5-1μg/ml (datasheet PA1329) |
| 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 | NOS1-positive staining in neuronal cells of caudate (HPA tissue IHC: High). HPA tissue profile: Cytoplasmic expression in a subset of neurons and renal distal tubules. No signal in the no-primary control. |
💡Decision noteStart with citrate pH 6.0 retrieval at 95–98 °C for 20 min (page antigen-retrieval rule). The lung study used pressure retrieval for 30 min (PMC5882435).
Section 2
What Is the Expected NOS1 Staining Pattern?
NOS1 should stain a subset of neurons and renal distal tubules, chiefly in the cytoplasm on tissue IHC (HPA tissue IHC). Sarcolemmal localization in fast-twitch muscle fibers and enrichment in dendritic spines are annotated by similarity (UniProt P29475). NOS1 has no transmembrane segment (UniProt P29475 topology). HPA rates its tissue IHC profile Enhanced, while reporting medium consistency between staining and RNA expression (HPA tissue IHC).
| Selective neuronal staining in caudate or cerebellum; distal-tubule staining in kidney. | This fits the reported distribution: caudate neurons and cerebellar molecular-layer cells stain High, while renal distal tubules stain Medium (HPA tissue IHC). Judge the labeled cell population as well as intensity; a uniformly stained section does not reproduce this selective pattern (HPA tissue IHC). |
| Predominantly nuclear staining on a chromogenic tissue section. | Recheck cell identity and detection controls: HPA describes tissue IHC as cytoplasmic in neuronal subsets and distal tubules (HPA tissue IHC). Nucleoplasm is an additional approved location in ICC-IF, so nuclear signal alone cannot be dismissed across assay types; it does not establish the expected tissue IHC pattern (HPA subcellular ICC-IF). |
| Strong staining across adipocytes, glandular cells, or renal cells outside distal tubules. | Check for cross-reactivity or endogenous detection activity before calling this NOS1: HPA reports no detection in adipocytes in adipose tissue, several sampled glandular populations, and specifies distal tubules for kidney positivity (HPA tissue IHC). These reference negatives apply to the listed cells, not every cell in those tissues. |
| Diffuse color over cells, stroma, and tissue edges with little cellular distinction. | Treat this as background until controls resolve it (general IHC practice). Excess detection reagent, incomplete blocking, and residual endogenous enzyme activity are general chromogenic IHC possibilities (general IHC practice); the supplied NOS1 sources do not identify a target-specific cause. |
| No visible staining in caudate neurons or cerebellar molecular-layer cells. | These are reported High reference populations (HPA tissue IHC). A blank known-positive section raises concern about the staining run or specimen quality (general IHC practice), but one negative slide cannot establish loss of NOS1; review controls and tissue integrity before interpreting the sample. |
💡Expected NOS1 appearanceCall a result consistent with NOS1 when selected neurons show chiefly cytoplasmic staining, with High reference staining in caudate neurons or cerebellar molecular-layer cells and Medium staining in renal distal tubules; broad staining of HPA-negative cell populations is suspect (HPA tissue IHC).
| Tissue and cell selection | HPA reports High neuronal staining in caudate and cerebellum, Medium neuronal staining in cortex and hippocampus, and Medium distal-tubule staining in kidney (HPA tissue IHC). Skeletal myocytes are Low by tissue IHC despite skeletal-muscle RNA enrichment, so a weak muscle section alone is a poor test of assay failure (HPA tissue IHC). |
| Subcellular and isoform context | UniProt places NOS1 beneath the sarcolemma in fast-twitch fibers and in neuronal dendritic spines, both by similarity (UniProt P29475). It lists 5 isoforms with differing tissue expression (UniProt P29475). An antibody's epitope and isoform coverage are not supplied, so these annotations cannot predict that every isoform will be detected. |
| Antibody validation | HPA lists IHC Enhanced for HPA069509 and CAB002167; HPA058312 has ICC Supported status but no listed IHC status (HPA antibodies). These statuses support choosing an IHC-validated antibody for tissue interpretation, but do not specify its epitope, dilution, retrieval condition, or performance in every specimen. |
| IF/ICC: what pattern is reported? | HPA reports mainly plasma-membrane localization, with additional approved nucleoplasmic localization, in ICC-IF; images are listed for HaCaT and U2OS (HPA subcellular ICC-IF). This is assay-specific evidence and should not replace the cytoplasmic tissue IHC profile or be treated as an IHC-P protocol (HPA tissue IHC; HPA subcellular ICC-IF). |
| Situation | Likely cause | Next action |
|---|---|---|
| Known-positive neuronal tissue is blank. | The run may have failed, or the specimen may lack interpretable antigen signal (general IHC practice). | Check the IHC-validated antibody's control staining and the detection run, then assess tissue morphology before scoring; caudate neurons and cerebellar molecular-layer cells are High references (HPA antibodies; HPA tissue IHC). |
| Only skeletal muscle gives weak staining. | HPA lists skeletal myocytes as Low by tissue IHC, even though skeletal muscle belongs to an RNA-enriched group (HPA tissue IHC). | Compare with a High neuronal reference before changing the assay; interpret muscle at the cell and compartment level, since sarcolemmal localization is annotated by similarity (HPA tissue IHC; UniProt P29475). |
| Negative-reference cells show strong color. | Cross-reactivity or endogenous chromogenic activity is possible (general IHC practice). | Inspect an appropriate negative reagent control and address endogenous activity in the detection workflow (general IHC practice). Compare only matched cell types: HPA reports adipose adipocytes and adrenal glandular cells as Not detected (HPA tissue IHC). |
| Nuclear color dominates the tissue section. | It differs from HPA's chiefly cytoplasmic tissue IHC profile; ICC-IF separately allows additional nucleoplasmic localization (HPA tissue IHC; HPA subcellular ICC-IF). | Review morphology and negative controls, then score the expected neuronal or distal-tubule pattern. Do not transfer an ICC-IF compartment call directly to chromogenic tissue IHC (HPA tissue IHC; HPA subcellular ICC-IF). |
| Diffuse background obscures cellular boundaries. | Nonspecific reagent binding or detection background is possible (general IHC practice). | Review blocking, antibody concentration, washing, and chromogen development using the assay's controls (general IHC practice). No NOS1-specific dilution or background mechanism is supplied by UniProt or HPA. |
| Signal changes after retrieval adjustment. | Retrieval can change staining in general IHC practice, but the supplied NOS1 records do not establish a target-specific retrieval or fixation effect. | Compare conditions on matched positive and negative sections with the same detection workflow (general IHC practice). Keep the condition that preserves selective neuronal or distal-tubule staining against the HPA reference pattern (HPA tissue IHC). |
Experiment evidence
IHC & IF images showing NOS1 staining
PA1329 · IHCAnti-nNOS(neuronal) antibody, PA1329, IHC(P) IHC(P): Rat Brain Tissue
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000089250-NOS1/tissue/cerebral+cortex#imid_20705680
HPA · CaudateHuman Protein Atlas IHC, Caudate. Source: https://www.proteinatlas.org/ENSG00000089250-NOS1/tissue/basal+ganglia#imid_20705682
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000089250-NOS1/tissue/colon#imid_20700190
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000089250-NOS1/tissue/liver#imid_20700207
HPA · ICC-IF HaCaTHuman Protein Atlas immunofluorescence, HaCaT, antibody HPA058312; green = NOS1, blue = nucleus, red = microtubules.
HPA · ICC-IF HaCaTHuman Protein Atlas immunofluorescence, HaCaT, antibody HPA058312; green = NOS1, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for NOS1 IHC & IF
🧪Run caudate first and expect neuronal cells to stain (HPA: High in caudate neuronal cells). Use adipose tissue as a negative tissue, where adipocytes are not detected (HPA: Not detected in adipocytes); on the caudate slide, assess adjacent non-neuronal cells for background staining rather than assuming they are NOS1-negative.
Positive control tissue: Caudate (Neuronal cells, HPA High)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show NOS1 in HaCaT, U2OS, with annotated localisation: Plasma membrane (supported) (HPA subcellular).
Technical controls: Include a no-primary (secondary-only) control, a host- and isotype-matched immunoglobulin for a monoclonal primary or matched nonimmune immunoglobulin for a polyclonal primary, and NOS1-knockout tissue where available (standard IHC practice). For chromogenic caudate IHC, block endogenous peroxidase and check pigment or blood-associated signal against the no-primary slide (standard IHC practice).
⚠️Feasibility: A target-specific fixation window and retrieval dependency are unreported in the supplied evidence; the PA1329 rat-brain IHC(P) caption does not state its fixative (selected PA1329 caption). The supplied evidence does not establish whether frozen sections or IF would be easier than paraffin IHC, although NOS1 plasma-membrane localization has ICC-IF support (HPA: subcellular). Brain pigment and blood-associated peroxidase can complicate chromogenic interpretation (standard IHC practice).
HPA tissue IHC evidence for NOS1
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Enhanced — 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 |
|---|---|---|---|---|
| Caudate | Neuronal cells | High | Protein (IHC) | HPA → |
| Cerebellum | Molecular layer cells - cytoplasm/membrane | High | Protein (IHC) | HPA → |
| Cerebral cortex | Neuronal cells | Medium | Protein (IHC) | HPA → |
| Hippocampus | Neuronal cells | Medium | Protein (IHC) | HPA → |
| Kidney | Distal tubules | Medium | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Adipose tissue | Adipocytes | Not detected | Protein (IHC) | HPA → |
| Adrenal gland | Glandular cells | Not detected | Protein (IHC) | HPA → |
| Appendix | Glandular cells | Not detected | Protein (IHC) | HPA → |
| Bone marrow | Hematopoietic cells | Not detected | Protein (IHC) | HPA → |
| Breast | Adipocytes | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced NOS1 IHC Tips
These NOS1 troubleshooting answers focus on paraffin sections with chromogenic IHC; the immunofluorescence entry addresses the separate IF workflow.
What should I change when NOS1 staining is weak after retrieval?
Start with citrate buffer at pH 6.0 for heat-induced antigen retrieval at 95–98 °C for 20 min (page retrieval setting). If staining remains weak, compare a longer incubation or a different retrieval buffer on adjacent sections, changing one condition at a time and watching for tissue damage (standard IHC practice). Keep the primary-antibody dilution and chromogen development time constant during that comparison so a stronger signal can be attributed to retrieval (standard IHC practice). Judge improvement by staining in neuronal cells or renal distal tubules, rather than by a uniform rise in background (HPA: NOS1 tissue IHC profile).
Could fixation be masking NOS1 in my paraffin sections?
Target-specific NOS1 sensitivity to fixation is unknown from the supplied evidence; the PA1329 rat-brain IHC(P) caption does not state a fixative (PA1329 tissue-IHC caption). Record the fixative, fixation duration, processing schedule, and section age before comparing staining across blocks (standard IHC practice). If material is available, compare sections processed under documented conditions using the same citrate pH 6.0, 95–98 °C, 20 min retrieval setting (page retrieval setting). Interpret a difference as a processing effect in those specimens, without assigning NOS1 a fixation preference until a controlled comparison establishes one (standard IHC practice).
Which staining compartment is plausible for NOS1?
Expect a cell-associated cytoplasmic or membrane pattern in relevant cells: HPA reports cytoplasmic staining in subsets of neurons and renal distal tubules (HPA: NOS1 tissue IHC profile). UniProt places NOS1 at the sarcolemma and dendritic spines, while reporting 0 transmembrane segments; membrane-adjacent staining need not form a continuous surface outline (UniProt P29475: localisation and topology). HPA subcellular data also support plasma-membrane localisation and approve an additional nucleoplasmic location, so compartment alone cannot establish antibody specificity (HPA: NOS1 subcellular profile). Compare the pattern with tissue morphology at the same chromogen development time, and scrutinise diffuse staining outside the expected cells (standard IHC practice; HPA: NOS1 tissue IHC profile).
Can this stain distinguish NOS1 isoforms or phosphorylation states?
Do not assign an isoform from staining alone: UniProt lists 5 NOS1 isoforms, while no epitope map for the catalog antibody is supplied (UniProt P29475: isoforms; supplied antibody evidence). Isoform 1 is detected in brain and skeletal muscle, whereas isoform 3 is reported only in testis; tissue context can inform interpretation but does not identify the stained isoform (UniProt P29475: tissue specificity). NOS1 also has reported phosphoserines at positions 852, 862, and 863 (UniProt P29475: modified residues). Establish antibody epitope coverage and modification sensitivity with appropriate validation before interpreting a staining change as alternative splicing or phosphorylation (standard IHC practice).
How should I adapt NOS1 localisation checks for multiplex IF?
On the separate IF page, pair NOS1 with a validated neuronal marker when examining brain, and inspect whether signals occupy the expected cells (HPA: neuronal staining; standard IF practice). Choose spectrally separated fluorophores and consider a far-red NOS1 channel if tissue autofluorescence compromises shorter wavelengths; include an unstained section to assess that background (standard IF practice). UniProt reports 0 transmembrane segments, but the antibody epitope is unspecified, so determine epitope accessibility before setting permeabilisation conditions (UniProt P29475: topology; supplied antibody evidence). Compare a mild permeabilisation condition with an unpermeabilised control while holding exposure and antibody concentration constant, and confirm localisation across optical sections (standard IF practice).
How can I reduce diffuse or misleading brown staining?
Run a no-primary control through secondary detection and DAB development to reveal reagent-dependent background, and inspect an adjacent section for endogenous pigment (standard chromogenic IHC practice). Block endogenous peroxidase before detection, then optimise protein blocking, washes, primary-antibody concentration, and chromogen time one variable at a time (standard chromogenic IHC practice). Compare candidate conditions on a section containing expected neuronal cells or renal distal tubules, using the same 20 min citrate retrieval baseline (HPA: NOS1 tissue IHC profile; page retrieval setting). Reject a condition that strengthens diffuse staining in cells without the expected distribution, even if its overall brown signal increases (HPA: NOS1 tissue IHC profile; standard IHC practice).
How should I score NOS1 staining across sections? ⚠ ANSWER MARKED FOR VERIFICATION
Define the region and cell population before scoring; neuronal cells and renal distal tubules are documented NOS1-positive populations in HPA tissue IHC (HPA: NOS1 tissue IHC profile). Report the percentage of positive cells and, when intensity is reproducibly graded, an H-score from 0–300 using the same positivity threshold across sections (standard IHC scoring practice). Normalise positive-cell counts to all eligible cells in the defined population, or report positive-cell density per mm² of evaluable tissue (standard IHC quantification practice). Exclude folds, damaged edges, and necrotic regions by prespecified criteria, and keep retrieval, imaging, and chromogen development consistent between groups (standard IHC practice).
What would distinguish a credible NOS1 signal from artefact?
A credible result should have a plausible cell distribution and compartment: HPA reports cytoplasmic NOS1 in subsets of neurons and renal distal tubules (HPA: NOS1 tissue IHC profile). Membrane-adjacent signal can also fit reported sarcolemmal or dendritic-spine localisation, although those UniProt assignments include similarity-based evidence (UniProt P29475: localisation). Treat staining limited to section edges, necrotic areas, or endogenous-peroxidase-rich deposits cautiously, and compare it with a no-primary control processed through DAB (standard chromogenic IHC practice). The PA1329 image documents rat-brain IHC(P) but leaves fixation unstated; a single image or positive-looking field cannot establish fixation compatibility, isoform identity, or specificity (PA1329 tissue-IHC caption; UniProt P29475: 5 isoforms).
Boster reagents
Best NOS1 / Nitric oxide synthase 1 IHC Antibodies
PA1329 has a rat brain paraffin-section IHC image (PA1329 image caption) and listed Human, Mouse, and Rat reactivity (catalog reactivity). No IF figure is supplied (catalog images).
Real IHC data
Anti-nNOS (neuronal)/NOS1 Antibody ®
Cat # PA1329
PA1329 is listed for IHC and for Human, Mouse, and Rat reactivity (catalog applications/reactivity). Its own figure shows rat brain tissue stained by IHC(P) (PA1329 image caption).
Which to pick: For tissue IHC, choose PA1329: its own figure shows rat brain paraffin-section staining (PA1329 image caption), with a listed IHC concentration of 0.5–1 μg/ml (PA1329 catalog dilution); the fixative is unreported (PA1329 image caption). For work across Human, Mouse, and Rat, PA1329 lists all three as reactive (PA1329 catalog reactivity), though its IHC figure shows rat brain only (PA1329 image caption). No SKU in this catalog is listed for IF/ICC or has an IF figure, so none can be recommended for IF/ICC from these data (catalog applications/images).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry P29475 (NOS1_HUMAN, Nitric oxide synthase 1).
- Human Protein Atlas. NOS1 tissue IHC expression (reliability: Enhanced).
- Human Protein Atlas. NOS1 subcellular location (ICC-IF): Mainly localized to the plasma membrane. In addition localized to the nucleoplasm..
- Human Protein Atlas. NOS1 antibody validation summary (3 antibodies).
- Loss of NOS1 expression in high-grade renal cell carcinoma associated with a shift of NO signalling. British journal of cancer 2004 — PMC2409527.
- CXCL14 and NOS1 expression in specimens from patients with stage I-IIIA nonsmall cell lung cancer after curative resection. Medicine 2018 — PMC5882435.
- Novel oxygen sensing mechanism in the spinal cord involved in cardiorespiratory responses to hypoxia. Science advances 2022 — PMC8956269.
- NOS1 upregulates ABCG2 expression contributing to DDP chemoresistance in ovarian cancer cells. Oncology letters 2019 — PMC6341833.
- PubMed PMID:7528745 — UniProt-cited evidence.
- PubMed PMID:7515942 — UniProt-cited evidence.
- PubMed PMID:7678401 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for NOS1 (Nitric oxide synthase 1). Expected localisation Cytoplasm in neurons and renal distal tubules (HPA tissue IHC). Antigen retrieval: Citrate pH 6.0 HIER, 95–98 °C, 20 min (rule: cytoplasmic / membrane antigen). Validated IHC antibody: PA1329 at 0.5-1μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Caudate (Neuronal cells); negative Adipose tissue. IHC workflow; specimen preparation unspecified. Protocol steps: 1. Sample: Tissue sections; selected-image fixative not specified (standard IHC workflow); 2. Fixation: Image fixative and duration unreported (datasheet PA1329); 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 citrate buffer, pH 6.0 , 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-NOS1, 0.5-1μg/ml (datasheet PA1329); 9. Primary incubation: Overnight at 4 °C (standard). Watch for: Fixation: Matched tissue-IHC evidence does not establish the fixation claim. Validate the specimen-specific method before use. (selected-SKU IHC image PA1329); Caveat: Muscle RNA enrichment may exceed observed myocyte staining (HPA tissue IHC/RNA); Isoform / epitope: 5 isoforms; intracellular access matters; epitope coverage unknown (UniProt; datasheet); Regulation: Isoform 3 is testis restricted (UniProt). Evidence: UniProt P29475, HPA tissue IHC · Enhanced, HPA ICC-IF · Mainly localized to the plasma membrane. In addition localized to…, Datasheet PA1329, PMC2409527, PMC5882435. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/NOS1/immunohistochemistry-ihc-guide.