TPH1 / Tryptophan 5-hydroxylase 1 · IHC design guide

Design Immunohistochemistry for TPH1

Plan TPH1 staining in paraffin sections around the granular cytoplasmic pattern reported in glandular cells (HPA tissue IHC). This guide covers the catalog antibody’s IHC conditions (datasheet A01626-4) and controls for uncertain staining specificity (HPA tissue IHC).

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

Immunohistochemistry protocol sheet for TPH1 (IHC for TPH1): expected localisation Granular cytoplasmic tissue staining (HPA tissue IHC), antibody A01626-4, validated IHC image, and IHC protocol steps — Printable **TPH1** IHC protocol sheet — expected localisation Granular cytoplasmic tissue staining (HPA tissue IHC), antibody A01626-4, controls and protocol steps. Open the full TPH1 IHC guide →

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TPH1 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	Granular cytoplasmic tissue staining (HPA tissue IHC)
	Staining pattern	Granular cytoplasm in glandular cells (HPA tissue IHC)
	Antigen retrieval	EDTA pH 8.0 HIER, heat-mediated (datasheet A01626-4)
	Positive control ⓘ	Colon+4 more · see all
	Negative control ⓘ	Adipose tissue+1 more · see all

Important caveats

Reasons your staining may differ from the expected pattern.

	Fixation	Keep fixation consistent across sections. (standard IHC practice; not target-specific)
	Caveat	Presumed off-target binding can mimic TPH1 staining (HPA tissue IHC)
	Regulation	Signal varies by tissue (HPA tissue IHC)
	Isoform / epitope	2 isoforms; epitope coverage is unresolved (UniProt)

Section 1

Recommended TPH1 IHC & IF Protocols

The catalog antibody protocol is accompanied by published TPH1 IHC protocols for rat organs, human liver, and human placenta (PMC5609917; PMC7156786; PMC6724713).

Recommended immunohistochemistry (IHC-P) protocol parameters
Sample	Paraffin-embedded human bladder epithelial carcinoma tissue; fixative not specified (datasheet A01626-4)
Fixation	Image fixative and duration unreported (datasheet A01626-4); 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 A01626-4); 20 min, 95–100 °C (standard)
Peroxidase block	3% H2O2, 10 min, room temperature (standard)
Blocking	10% goat serum (datasheet A01626-4)
Primary antibody	Rabbit anti-TPH1, 2-5 μg/ml (datasheet A01626-4)
Primary incubation	Overnight at 4 °C (datasheet A01626-4)
Detection	Streptavidin-biotin complex (SABC), DAB chromogen (datasheet A01626-4)
Counterstain	Hematoxylin, blue, dehydrate and mount (standard)
Expected result	TPH1-positive staining in glandular cells of colon (HPA tissue IHC: High). HPA tissue profile: General cytoplasmic expression with a granular pattern. No signal in the no-primary control.

💡Decision noteStart with heat-mediated EDTA at pH 8.0 for the catalog antibody (datasheet: A01626-4). The two published protocols that specify retrieval use citrate buffer (PMC5609917; PMC7156786).

Section 2

What Is the Expected TPH1 Staining Pattern?

TPH1 should appear mainly as granular cytoplasmic staining in glandular cells of colon, duodenum, rectum, small intestine, and stomach (HPA: tissue IHC profile; High in these cells). Cytosolic localization is supported separately by ICC-IF (HPA: Cytosol approved). TPH1 has no transmembrane segment (UniProt P17752 topology). Interpret tissue staining cautiously: HPA rates its IHC evidence Uncertain and reports presumed off-target binding (HPA: tissue IHC reliability).

What am I looking at on my slide?
Granular cytoplasmic stain in gastrointestinal glandular cells, with little stain outside those cells.	This fits the reported tissue pattern and the High staining recorded in colon, duodenum, rectum, small intestine, and stomach (HPA: tissue IHC). It is a plausible positive result, subject to the Uncertain IHC reliability rating (HPA: tissue IHC reliability).
Predominantly nuclear or sharply membrane-bound signal, with little cytoplasmic staining.	The compartment conflicts with granular cytoplasmic tissue staining and approved cytosolic ICC-IF localization (HPA: tissue IHC profile; Cytosol approved). Review morphology, counterstain, and controls before assigning it to TPH1; UniProt reports no transmembrane segment (UniProt P17752 topology).
Strong staining in adipocytes or soft-tissue fibroblasts, especially if gastrointestinal glandular cells are weak.	HPA reports TPH1 as Not detected in those cells (HPA: adipocytes; soft-tissue fibroblasts). Unexpected staining may reflect cross-reactivity or detection background; HPA reports presumed off-target binding in its tissue IHC assessment (HPA: tissue IHC reliability).
Uniform stain across cells, stroma, and empty spaces, without a discernible granular cell pattern.	That distribution does not match the reported granular cytoplasmic profile (HPA: tissue IHC profile). As general IHC practice, examine the reagent-only control and review blocking, washes, and chromogen exposure before scoring cells as positive.
No discernible stain in gastrointestinal glandular cells on a run expected to show TPH1.	A negative result needs a run check because HPA records High staining in several gastrointestinal glandular populations (HPA: tissue IHC). Confirm tissue morphology and positive-control performance, then review retrieval, primary incubation, and detection as general IHC checks; the HPA IHC rating remains Uncertain.

💡Expected TPH1 appearanceCall a section plausibly positive when gastrointestinal glandular cells show conspicuous granular cytoplasmic stain (HPA: High; granular cytoplasmic tissue profile); isolated nuclear, membrane-bound, or broadly uniform staining warrants control review (HPA: Cytosol approved; tissue IHC reliability Uncertain).

How each factor affects the staining
Tissue evidence and confidence	HPA records High glandular-cell staining in colon, duodenum, rectum, small intestine, and stomach, but rates tissue IHC Uncertain and notes presumed off-target binding (HPA: tissue IHC). Treat the distribution as a guide to interpretation, with controls alongside it.
Compartment evidence	The granular cytoplasmic tissue profile and approved cytosolic ICC-IF assignment agree on a cytoplasmic expectation (HPA: tissue IHC profile; Cytosol approved). The ICC-IF approval does not change the separate Uncertain rating for tissue IHC (HPA: antibody validation).
Comparison tissue and cell type	Adipocytes and soft-tissue fibroblasts are reported Not detected, while adrenal glandular cells and bone-marrow hematopoietic cells are Medium (HPA: tissue IHC). Score the named cell population within each tissue; whole-section darkness cannot substitute for cell-level assessment.
Protein form and epitope	UniProt lists two isoforms, no signal peptide or propeptide, and a chain spanning residues 1–444 (UniProt P17752: isoforms; processing). The supplied record gives no antibody epitope, so it cannot establish whether the catalog antibody distinguishes isoforms.
IF/ICC Q&A: where is the expected signal?	Cytosol is the approved ICC-IF location, with images listed for A-431, U-251MG, and U2OS (HPA: subcellular). Use that as compartment context only; this section makes no IF/ICC protocol recommendation.

Why is my staining missing, weak or wrong?
Situation	Likely cause	Next action
Gastrointestinal glandular cells are negative, and the run control is also weak.	The run may have insufficient detectable signal; HPA reports High staining in these glandular cells, but its tissue IHC rating is Uncertain (HPA: tissue IHC).	As general IHC practice, verify control tissue, retrieval and primary-antibody conditions, detection reagents, and chromogen development before interpreting the sample as negative.
A section is strongly stained throughout, including areas without intact cells.	Nonspecific detection or overdevelopment can obscure the granular cytoplasmic pattern reported by HPA (HPA: tissue IHC profile).	Inspect the reagent-only control; review blocking, washes, and development time as general IHC checks. Score only signal that can be assigned to intact cells.
Nuclear stain dominates in an otherwise well-preserved section.	That location disagrees with HPA's granular cytoplasmic tissue profile and approved cytosolic ICC-IF location (HPA: tissue IHC; subcellular).	Check the counterstain and reagent-only control, then reassess compartment assignment. Do not use nuclear intensity alone as evidence of TPH1.
Adipocytes or soft-tissue fibroblasts stain as strongly as gastrointestinal glandular cells.	These cell types are reported Not detected, and HPA flags presumed off-target binding in tissue IHC (HPA: tissue IHC).	Compare staining with the control and with glandular-cell morphology; treat the unexpected positive cells as unresolved until specificity is supported.
Only weak, scattered stain appears in cerebral cortical neurons, lung alveolar cells, or ovarian follicle cells.	HPA lists these populations as Low, so weak signal alone does not establish a failed run or a strong positive (HPA: tissue IHC low-expression entries).	Use the gastrointestinal glandular-cell comparison and run controls to judge assay performance; record the observed cell type and intensity separately.
Two antibody results disagree on which cells are positive.	The listed tissue IHC assessments are Uncertain for both HPA022483 and CAB010767 (HPA: antibody validation); HPA also reports presumed off-target binding (HPA: tissue IHC reliability).	Compare matched sections, cell morphology, and controls before interpreting either pattern as TPH1. Report the disagreement when scoring the result.

Source: UniProt P17752 Human Protein Atlas tissue Human Protein Atlas subcellular

Experiment evidence

IHC & IF images showing TPH1 staining

IHC analysis of Tryptophan Hydroxylase/TPH1 using anti-Tryptophan Hydroxylase/TPH1 antibody (A01626-4). Tryptophan Hydroxylase/TPH1 was detected in a paraffin-embedded section of human bladder epithelial carcinoma tissue. Heat mediated antigen retrieval was performed in EDTA buffer (pH 8.0, epitope retrieval solution). The tissue section was blocked with 10% goat serum. The tissue section was then incubated with 2 μg/ml rabbit anti-Tryptophan Hydroxylase/TPH1 Antibody (A01626-4) 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.

A01626-4 · IHCIHC analysis of Tryptophan Hydroxylase/TPH1 using anti-Tryptophan Hydroxylase/TPH1 antibody (A01626-4). Tryptophan Hydroxylase/TPH1 was dete

IF analysis of Tryptophan Hydroxylase/TPH1 using anti-Tryptophan Hydroxylase/TPH1 antibody (A01626-4). Tryptophan Hydroxylase/TPH1 was detected in an immunocytochemical section of A431 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 5 μg/mL rabbit anti-Tryptophan Hydroxylase/TPH1 Antibody (A01626-4) overnight at 4°C. DyLight®488 Conjugated Goat Anti-Rabbit IgG (BA1127) 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.

A01626-4 · IFIF analysis of Tryptophan Hydroxylase/TPH1 using anti-Tryptophan Hydroxylase/TPH1 antibody (A01626-4). Tryptophan Hydroxylase/TPH1 was detec

HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000129167-TPH1/tissue/cerebral+cortex#imid_5729740

HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000129167-TPH1/tissue/colon#imid_5729666

HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000129167-TPH1/tissue/liver#imid_5729667

HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000129167-TPH1/tissue/kidney#imid_5729660

HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA022483; green = TPH1, blue = nucleus, red = microtubules.

← swipe / scroll for more images →

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

Sample controls for TPH1 IHC & IF

🧪Run colon first and look for staining in glandular cells (HPA: High in colon glandular cells). Use adipose tissue adipocytes as the negative tissue (HPA: Not detected in adipocytes); on the colon slide, use adjacent nonglandular cells to assess background, without assuming they are validated TPH1-negative cells (standard IHC practice).

Positive control tissue: Colon (Glandular cells, HPA High)

Negative control tissue: Adipose tissue (HPA Not detected)

ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show TPH1 in A-431, U-251MG, U2OS, with annotated localisation: Cytosol (approved) (HPA subcellular).

Technical controls: Run a no-primary (secondary-only) control, a concentration-matched rabbit IgG isotype control, and a TPH1 knockout biological negative if available (A01626-4 IHC caption: rabbit primary; standard IHC practice). For colon sections, quench endogenous peroxidase and assess endogenous biotin when using the caption’s biotin-based DAB detection (A01626-4 IHC caption: biotin/SABC-DAB; standard IHC practice).

⚠️Feasibility: The selected-SKU paraffin-section caption does not report a fixative, and the supplied evidence reports no TPH1-specific fixation window or fixation effect (A01626-4 IHC caption). It uses heat retrieval in EDTA at pH 8.0, but does not establish that retrieval is required (A01626-4 IHC caption). The evidence does not establish whether frozen sections or IF/ICC are easier; HPA reports cytosolic ICC-IF localisation as a check on staining pattern (HPA subcellular: Cytosol).

HPA tissue IHC evidence for TPH1

Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Uncertain — Pending external verification. Presumed off target binding observed and disregarded.). 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
Colon	Glandular cells	High	Protein (IHC)	HPA →
Duodenum	Glandular cells	High	Protein (IHC)	HPA →
Rectum	Glandular cells	High	Protein (IHC)	HPA →
Small intestine	Glandular cells	High	Protein (IHC)	HPA →
Stomach	Glandular cells	High	Protein (IHC)	HPA →

Undetected expression · recommended negative controls

Tissue	Cell type	Level	Evidence	Source
Adipose tissue	Adipocytes	Not detected	Protein (IHC)	HPA →
Soft tissue	Fibroblasts	Not detected	Protein (IHC)	HPA →

Section 3

Advanced TPH1 IHC Tips

Troubleshoot TPH1 staining in paraffin sections by checking retrieval, controls, cell identity and cytoplasmic localisation before interpreting chromogenic signal.

What retrieval should I try first when TPH1 staining is weak in paraffin sections?

Start with heat-mediated retrieval in EDTA at pH 8.0 (datasheet A01626-4). The selected paraffin-section example used this retrieval before applying the catalog antibody at 2 μg/ml overnight at 4°C (caption A01626-4). If staining remains weak, compare a citrate-buffer retrieval condition on adjacent sections while holding antibody concentration and detection conditions constant; treat that condition as an optimisation, not a validated TPH1 setting. Include a known positive section and a no-primary control in the same run, and compare cellular signal with tissue damage or diffuse background before increasing retrieval intensity.

How should I assess whether fixation is causing weak TPH1 IHC?

The selected example describes a paraffin-embedded section but does not report its fixative, so target-specific fixation sensitivity is unknown (caption A01626-4). Record the specimen's actual fixative and fixation interval, then compare sections with different documented histories using the same EDTA pH 8.0 retrieval and antibody concentration (datasheet A01626-4: retrieval; caption A01626-4: 2 μg/ml). If a control section stains but the study section does not, check preservation, section adhesion and morphology before attributing the difference to TPH1 abundance. Avoid assigning a fixation effect from the HPA staining pattern or TPH1's lack of a transmembrane segment (HPA tissue IHC; UniProt P17752 topology).

Which staining compartment should count as plausible TPH1 signal?

Look primarily for cytoplasmic staining: HPA reports a granular cytoplasmic tissue pattern and an approved cytosolic location in its subcellular dataset (HPA tissue IHC; HPA subcellular). TPH1 has no annotated transmembrane segment or signal peptide, which supports evaluating intracellular signal rather than a crisp membrane rim (UniProt P17752 topology and processing). Compare the apparent compartment with hematoxylin-stained cell outlines on the same section, and exclude pigment or precipitate outside intact cells from positive scoring. Because HPA marks its tissue IHC reliability Uncertain owing to presumed off-target binding, confirm an unexpected pattern with an independent specificity control (HPA tissue IHC).

Can this antibody distinguish TPH1 isoforms or preserve a phosphorylation-sensitive epitope?

TPH1 has 2 listed isoforms and an ACT domain at residues 19–94 (UniProt P17752 isoforms and domains). Serine 58 is annotated as a PKA phosphorylation site, but the supplied antibody evidence does not map its epitope or establish isoform selectivity (UniProt P17752 modified residues; caption A01626-4). Interpret a positive chromogenic section as antibody-reactive TPH1 signal unless epitope mapping or isoform-specific validation establishes more. If specimens differ unexpectedly, compare staining with an independently validated reagent or orthogonal assay, and avoid treating a retrieval-dependent change as evidence of phosphorylation or a particular isoform.

How can I follow up a TPH1 IHC pattern with multiplex IF?

Use IF as a separate optimisation: the selected antibody example documents chromogenic staining in a paraffin section, with no IF protocol specified (caption A01626-4). Pair TPH1 with an independently validated marker for the glandular cells being examined, since HPA lists high glandular-cell staining in colon, duodenum, rectum, small intestine and stomach (HPA tissue IHC). Choose fluorophores after measuring tissue autofluorescence in unstained sections, and use single-stain controls to assess bleed-through. For an intracellular epitope, optimise gentle permeabilisation after fixation; HPA assigns TPH1 to the cytosol, while UniProt reports no transmembrane segment (HPA subcellular; UniProt P17752 topology).

How do I reduce diffuse brown staining without losing TPH1-positive cells?

First check the no-primary section, then reduce nonspecific binding with an appropriate protein block; the selected example used 10% goat serum before 2 μg/ml primary antibody overnight at 4°C (caption A01626-4). For peroxidase and DAB detection, include a routine endogenous-peroxidase block and control development time as general chromogenic IHC practice. The selected example used a biotinylated secondary for 30 minutes at 37°C, followed by a streptavidin-biotin complex and DAB, so test secondary-only and endogenous-biotin controls if background persists (caption A01626-4). Judge improvements by retained cellular staining and reduced no-primary signal.

What should I score when comparing TPH1 across paraffin sections? ⚠ ANSWER MARKED FOR VERIFICATION

Define the target cell population before scoring: HPA reports high staining in glandular cells of colon, duodenum, rectum, small intestine and stomach (HPA tissue IHC). For chromogenic sections, record the percentage of positive target cells and an H-score based on staining intensity; use positive cells per mm² when cell abundance itself is the question. Normalise to the number or area of evaluable target cells, and keep retrieval, antibody concentration, development and image thresholds consistent across samples. Report no-primary background separately and flag that HPA rates its tissue IHC evidence Uncertain because presumed off-target binding was observed (HPA tissue IHC).

How can I distinguish convincing TPH1 staining from artefact?

A plausible result is intracellular, predominantly cytoplasmic signal in intact cells, consistent with HPA's cytosolic assignment and granular tissue pattern (HPA subcellular; HPA tissue IHC). Check whether staining follows the expected glandular-cell distribution in the sampled tissue; HPA lists high glandular-cell staining in several gastrointestinal tissues, but rates its tissue IHC reliability Uncertain because presumed off-target binding was observed (HPA tissue IHC). Treat isolated nuclear or membrane rims, section-edge intensification, necrotic deposits and staining in no-primary controls as reasons to investigate artefact. For DAB IHC, compare an endogenous-peroxidase-blocked control and seek independent specificity evidence before assigning unexpected positive cells to TPH1.

Boster reagents

Best TPH1 / Tryptophan 5-hydroxylase 1 IHC Antibodies

A01626-4 has human paraffin-section IHC images and an A431-cell IF image (catalog image captions). Its listed reactivity is human (catalog reactivity).

Real IHC data

Anti-Tryptophan Hydroxylase/TPH1 Antibody ®

Cat # A01626-4

View product →

A01626-4 is the only SKU with a card; its IHC captions show human bladder epithelial carcinoma, colonic adenocarcinoma, ovarian cancer, and small intestine paraffin sections (catalog IHC captions). Its IF caption shows A431 cells (catalog IF caption); M01626 has no IHC or IF figure, so it has no card (catalog image fields).

Which to pick: Choose A01626-4 for human paraffin-section IHC: its captions document that preparation, but do not report the fixative (catalog IHC captions). Choose A01626-4 for IF/ICC because its A431-cell IF image supports that use (catalog IF caption). For human, mouse, or rat IHC, M01626 is a rabbit monoclonal option, clone EDH-20, with those species and IHC listed; it has no IHC image caption documenting sample processing (catalog clone/applications/reactivity/image fields).

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

References

UniProt Consortium. UniProt entry P17752 (TPH1_HUMAN, Tryptophan 5-hydroxylase 1).
Human Protein Atlas. TPH1 tissue IHC expression (reliability: Uncertain).
Human Protein Atlas. TPH1 subcellular location (ICC-IF): Localized to the cytosol..
Human Protein Atlas. TPH1 antibody validation summary (2 antibodies).
Stress inhibits tryptophan hydroxylase expression in a rat model of depression. Oncotarget 2017 — PMC5609917.
Induction of tryptophan hydroxylase in the liver of s.c. tumor model of prostate cancer. Cancer science 2020 — PMC7156786.
Disrupted placental serotonin synthetic pathway and increased placental serotonin: Potential implications in the pathogenesis of human fetal growth restriction. Placenta 2019 — PMC6724713.
Placental lactogens induce serotonin biosynthesis in a subset of mouse beta cells during pregnancy. Diabetologia 2010 — PMC2974930.
PubMed PMID:2377472 — UniProt-cited evidence.
PubMed PMID:7986090 — UniProt-cited evidence.
PubMed PMID:15489334 — UniProt-cited evidence.