HAS1 / Hyaluronan synthase 1 · IHC design guide

Design Immunohistochemistry for HAS1

Plan chromogenic HAS1 IHC on paraffin sections using the catalog antibody and tissue controls selected from the reported staining profile (HPA tissue IHC). Interpret cytoplasmic staining (HPA tissue IHC) alongside membrane topology (UniProt) and the reported low consistency between antibody staining and RNA expression (HPA tissue IHC).

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

Immunohistochemistry protocol sheet for HAS1 (IHC for HAS1): expected localisation Cytoplasmic tissue staining (HPA tissue IHC); membrane protein (UniProt), antibody A04784-1, validated IHC image, and IHC protocol steps — Printable **HAS1** IHC protocol sheet — expected localisation Cytoplasmic tissue staining (HPA tissue IHC); membrane protein (UniProt), antibody A04784-1, controls and protocol steps. Open the full HAS1 IHC guide →

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HAS1 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); membrane protein (UniProt)
	Staining pattern	Cytoplasmic adipocytes, endothelial and smooth muscle cells; ECM (HPA tissue IHC)
	Antigen retrieval	Citrate pH 6 HIER, heat-mediated (datasheet A04784-1)
	Positive control ⓘ	Adipose tissue+3 more · see all
	Negative control ⓘ	Adrenal gland+4 more · see all

Important caveats

Reasons your staining may differ from the expected pattern.

	Fixation	Keep paraffin-section fixation consistent (standard IHC practice; not target-specific); Matched tissue-IHC evidence does not establish the fixation claim. Validate the specimen-specific method before use. (selected-SKU IHC image A04784-1)
	Caveat	Antibody staining has low consistency with RNA expression (HPA tissue IHC)
	Regulation	No specific expression regulator annotated (UniProt)
	Isoform / epitope	No isoforms or processing annotated; epitope side matters (UniProt)

Section 1

Recommended HAS1 IHC & IF Protocols

The catalog antibody’s IHC-P protocol is paired with four published HAS1 IHC protocols using paraffin tissue sections (PMC3166775; PMC12093883; PMC11764198; PMC6023397).

Recommended immunohistochemistry (IHC-P) protocol parameters
Sample	Paraffin-embedded human mammary cancer tissue; fixative not specified (datasheet A04784-1)
Fixation	Image fixative and duration unreported (datasheet A04784-1); 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 A04784-1)
Peroxidase block	3% H2O2, 10 min, room temperature (standard)
Blocking	10% goat serum (datasheet A04784-1)
Primary antibody	Rabbit anti-HAS1, 1:100–1:500 starting range (standard)
Primary incubation	Overnight at 4 °C (datasheet A04784-1)
Detection	Streptavidin-biotin complex (SABC), DAB chromogen (datasheet A04784-1)
Counterstain	Hematoxylin, blue, dehydrate and mount (standard)
Expected result	HAS1-positive staining in adipocytes of adipose tissue (HPA tissue IHC: High). HPA tissue profile: Cytoplasmic expression in adipocytes, extracellular matrix, endothelial cells and smooth muscle cells. No signal in the no-primary control.

💡Decision noteStart with pH 6 citrate heat retrieval (datasheet A04784-1); the endometrial cancer protocol used 0.25% trypsin instead (PMC3166775).

Section 2

What Is the Expected HAS1 Staining Pattern?

HAS1 is a seven-pass membrane protein (UniProt Q92839 topology). In tissue IHC, expect staining in adipocytes, extracellular matrix, endothelial cells and smooth muscle cells (HPA tissue IHC). Adipose adipocytes and testis peritubular cells show high staining (HPA tissue IHC). Interpret this pattern cautiously: HPA rates the tissue staining Approved but reports low consistency with RNA expression (HPA tissue IHC).

What am I looking at on my slide?
Adipocytes stain strongly in adipose tissue; testis peritubular cells also stain strongly (HPA tissue IHC).	These are useful reference patterns for the IHC-validated antibody (HPA tissue IHC). Judge signal in the identified cells rather than expecting every cell in either section to stain. HPA reports high staining for those specific cell populations (HPA tissue IHC).
Signal outlines cells or appears cytoplasmic; some signal follows extracellular matrix (HPA subcellular ICC-IF; HPA tissue IHC).	A membrane-associated pattern fits HAS1's seven transmembrane segments (UniProt Q92839 topology). HPA describes cytoplasmic and extracellular-matrix staining in tissue IHC, while its ICC-IF data support plasma-membrane localization (HPA tissue IHC; HPA subcellular ICC-IF). Interpret the compartments in the context of the assay used.
Strong nuclear-only staining dominates an IHC section (HPA tissue IHC comparison).	Treat it as a discordant IHC pattern and investigate nonspecific signal or scoring error (HPA tissue IHC; general IHC practice). Nuclear staining alone is not proof of artefact: HPA separately lists nucleoplasm as an additional ICC-IF location, with Approved status (HPA subcellular ICC-IF).
Adrenal glandular cells or bone-marrow hematopoietic cells stain prominently (HPA tissue IHC comparison).	HPA reports HAS1 as not detected in these cell populations (HPA tissue IHC). Prominent signal warrants checking cell identity, background and antibody specificity (general IHC practice). It cannot by itself establish cross-reactivity, especially given HPA's low staining-to-RNA consistency rating (HPA tissue IHC).
The entire section has diffuse color, or adipose adipocytes have no visible signal (HPA tissue IHC comparison).	Diffuse color that obscures cell boundaries can reflect background from detection or blocking steps (general IHC practice); do not automatically reject structured matrix staining described by HPA (HPA tissue IHC). An absent adipocyte signal conflicts with HPA's high adipocyte staining and calls for control review (HPA tissue IHC).

💡Expected HAS1 appearanceCall positive when identifiable adipose adipocytes show high staining with interpretable cell-associated signal (HPA tissue IHC; UniProt Q92839 topology); uniform color across unrelated cells is suspect background (general IHC practice).

How each factor affects the staining
Membrane topology and epitope access (UniProt Q92839 topology)	HAS1 has seven transmembrane segments and cytoplasmic and extracellular regions (UniProt Q92839 topology). The antibody epitope is unspecified here, so topology alone cannot justify a particular retrieval condition or predict staining intensity.
Choice of reference tissue and cell (HPA tissue IHC)	HPA reports high staining in adipose adipocytes and testis peritubular cells, but low staining in ovarian stromal cells (HPA tissue IHC). Score the named cell population; tissue-wide positivity would overstate the evidence.
Tissue-IHC reliability (HPA tissue IHC; HPA antibodies)	The tissue profile is Approved yet has low consistency with RNA expression; antibody HPA067602 has IHC status Approved (HPA tissue IHC; HPA antibodies). A plausible pattern therefore merits controls and should not be treated as independently confirmed expression.
IF/ICC Q&A: Where is HAS1 seen? (HPA subcellular ICC-IF)	HPA lists the plasma membrane as the supported main location and nucleoplasm as an Approved additional location in ICC-IF (HPA subcellular ICC-IF). This answers the localization question; the ICC-IF observation does not set an IHC-P protocol.

Why is my staining missing, weak or wrong?
Situation	Likely cause	Next action
No staining in adipose adipocytes, the high HPA reference population (HPA tissue IHC).	The run may have lost detectable signal, or the sampled cells may have been misidentified (general IHC practice). HPA's Approved rating does not guarantee positivity in every section (HPA tissue IHC).	Verify adipocyte identity and section quality, then review the catalog antibody's IHC-P instructions, detection reagents and a run control (general IHC practice). Record the negative finding if controls pass.
Strong staining appears in adrenal glandular cells, listed as not detected (HPA tissue IHC).	Cell misidentification, nonspecific binding or detection background may explain a mismatch (general IHC practice); HPA's low RNA-to-staining consistency limits certainty (HPA tissue IHC).	Compare the morphology and staining with an HPA-positive cell population; review antibody and detection controls before calling the adrenal signal HAS1 (HPA tissue IHC; general IHC practice).
Color spreads across most of the section and obscures cell borders (general IHC practice).	Diffuse detection background can obscure a specific pattern (general IHC practice). HPA also reports extracellular-matrix staining, so matrix-associated color alone is not evidence of failure (HPA tissue IHC).	Check the detection-only control and the blocking and wash steps; distinguish structured matrix signal from uniform haze before scoring (general IHC practice; HPA tissue IHC).
Nuclear-only IHC staining dominates the expected cell pattern (HPA tissue IHC comparison).	The result differs from HPA's tissue description, although nucleoplasm is an additional ICC-IF location (HPA tissue IHC; HPA subcellular ICC-IF). Assay context prevents a definitive artefact call.	Check cell identity, counterstain separation and antibody controls; report the compartment observed without using the ICC-IF result as IHC validation (general IHC practice; HPA subcellular ICC-IF).
Ovarian stroma stains weakly despite high ovarian expression in UniProt's tissue summary (UniProt Q92839; HPA tissue IHC).	HPA reports low ovarian stromal-cell staining, while UniProt describes ovary as highly expressed at the tissue level (HPA tissue IHC; UniProt Q92839 tissue specificity). These observations have different scopes.	Score the stromal cells against the HPA IHC observation and use high-staining adipose adipocytes as a clearer IHC reference (HPA tissue IHC). Do not infer a failed run from ovarian stroma alone.
Brown chromogen appears in a control lacking primary antibody (general IHC practice).	Endogenous detection activity or a detection-reagent background can produce signal without primary antibody (general IHC practice). This control does not establish HAS1 localization.	Resolve the detection background using the reagent instructions and rerun the control before assigning cell-specific HAS1 staining (general IHC practice).

Source: UniProt Q92839 Human Protein Atlas tissue Human Protein Atlas subcellular

Experiment evidence

IHC & IF images showing HAS1 staining

IHC analysis of HAS1 using anti-HAS1 antibody (A04784-1). HAS1 was detected in paraffin-embedded section of human mammary cancer tissue. 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 1ugμg/ml rabbit anti-HAS1 Antibody (A04784-1) 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.

A04784-1 · IHCIHC analysis of HAS1 using anti-HAS1 antibody (A04784-1). HAS1 was detected in paraffin-embedded section of human mammary cancer tissue. Hea

IF analysis of HAS1 using anti-HAS1 antibody (A04784-1). HAS1 was detected in immunocytochemical section of U20S cell. 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-HAS1 Antibody (A04784-1) 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.

A04784-1 · IFIF analysis of HAS1 using anti-HAS1 antibody (A04784-1). HAS1 was detected in immunocytochemical section of U20S cell. Enzyme antigen retrie

HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000105509-HAS1/tissue/cerebral+cortex#imid_18614780

HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000105509-HAS1/tissue/colon#imid_18614698

HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000105509-HAS1/tissue/liver#imid_18614707

HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000105509-HAS1/tissue/kidney#imid_18614700

HPA · ICC-IF A-549Human Protein Atlas immunofluorescence, A-549, antibody HPA067602; green = HAS1, blue = nucleus, red = microtubules.

← swipe / scroll for more images →

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

Sample controls for HAS1 IHC & IF

🧪Run adipose tissue first and score adipocytes for HAS1 staining (HPA: High in adipocytes), then run adrenal gland as a negative tissue and score its glandular cells for background staining (HPA: Not detected in glandular cells). Non-adipocyte cells on the adipose slide can serve as internal negatives only if their HAS1-negative status is independently established; in that case, they should show background staining (HPA: adipose row establishes expression in adipocytes only).

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

Negative control tissue: Adrenal gland (HPA Not detected)

ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show HAS1 in A-549, LHCN-M2, U2OS, with annotated localisation: Plasma membrane (supported) (HPA subcellular).

Technical controls: Include no-primary/secondary-only and host- and clonality-matched rabbit IgG controls, plus a HAS1 knockout specimen or a validated peptide-block control (caption: rabbit anti-HAS1; standard IHC practice). For SABC/DAB detection, quench endogenous peroxidase and check for endogenous biotin in the adipose section (caption: SABC/DAB; standard IHC practice).

⚠️Feasibility: A target-specific fixation window or fixation effect is unreported, and the selected A04784-1 tissue-IHC caption does not state a fixative (caption: fixative unreported). The reported paraffin-section procedure used heat retrieval in citrate buffer at pH 6 for 20 minutes; whether retrieval is essential for HAS1 is unreported (caption: retrieval conditions). Frozen-section or IF ease relative to paraffin IHC is unreported; preserve adipocyte morphology during sectioning and check for tissue background when scoring adipose sections (HPA: High in adipocytes; standard IHC practice).

HPA tissue IHC evidence for HAS1

Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Approved — Low 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
Adipose tissue	Adipocytes	High	Protein (IHC)	HPA →
Testis	Peritubular cells	High	Protein (IHC)	HPA →
Breast	Adipocytes	Medium	Protein (IHC)	HPA →
Smooth muscle	Smooth muscle cells	Medium	Protein (IHC)	HPA →

Undetected expression · recommended negative controls

Tissue	Cell type	Level	Evidence	Source
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 →
Bronchus	Respiratory epithelial cells	Not detected	Protein (IHC)	HPA →
Caudate	Glial cells	Not detected	Protein (IHC)	HPA →

Section 3

Advanced HAS1 IHC Tips

Troubleshoot HAS1 staining in paraffin sections by checking retrieval, compartment, detection background and cell-specific scoring against the supplied evidence.

Which antigen retrieval condition should I use first for HAS1 IHC?

Start with heat-mediated antigen retrieval in citrate buffer at pH 6 for 20 minutes (datasheet A04784-1). The selected paraffin-section image used this condition before overnight primary incubation at 4°C and DAB detection (datasheet A04784-1). Compare serial sections processed together, including a no-primary control, so uneven heating or section loss is not mistaken for weak HAS1 staining (standard IHC practice). If staining remains weak, adjust heating duration first, then evaluate another retrieval buffer as a fallback while monitoring tissue damage and background (standard IHC practice).

Could fixation explain variable HAS1 staining across paraffin sections?

The fixative and fixation duration are unreported for the selected paraffin-embedded human mammary cancer image, so target-specific fixation sensitivity remains unknown (datasheet A04784-1). Document the fixative, time to fixation and fixation duration for each specimen, and compare sections prepared on the same schedule (standard IHC practice). Use the documented citrate pH 6, 20-minute heat retrieval as a starting condition while holding antibody incubation and DAB development constant (datasheet A04784-1; standard IHC practice). If staining varies across batches, inspect morphology and section adhesion, then test fixation and retrieval changes separately on matched material before attributing differences to HAS1 expression (standard IHC practice).

Should HAS1 staining be membranous, cytoplasmic or extracellular?

HAS1 is annotated as a 7-segment membrane protein with a large cytoplasmic region at residues 73–398 (UniProt Q92839 topology). Supported plasma-membrane localisation in ICC/IF makes a cell-border pattern plausible, while HPA tissue IHC reports cytoplasmic signal in adipocytes, endothelial cells and smooth muscle cells (HPA subcellular; HPA tissue IHC). Because tissue staining also includes extracellular matrix, score cellular and extracellular compartments separately and review their morphology on adjacent sections (HPA tissue IHC; standard IHC practice). Do not interpret diffuse extracellular DAB as proof of secreted HAS1: the enzyme is membrane annotated, while its hyaluronan product contributes to extracellular matrix (UniProt Q92839 topology; UniProt Q92839 function).

Can an unexpected HAS1 pattern reflect isoforms or epitope accessibility?

UniProt lists 0 annotated HAS1 isoforms, but that does not establish which sequence a particular antibody recognizes (UniProt Q92839 isoforms; standard antibody validation practice). Obtain the immunogen or epitope coordinates for A04784-1 before assigning its IHC signal to a cytoplasmic or extracellular loop (standard antibody validation practice). HAS1 crosses the membrane 7 times, with cytoplasmic residues 73–398 and short extracellular loops, so epitope accessibility may differ with retrieval and section processing (UniProt Q92839 topology; standard IHC practice). Record antibody lot and processing conditions, and compare the staining pattern with a no-primary control when an unexpected compartment appears (standard IHC practice).

How can IF help check HAS1 localisation without confusing tissue autofluorescence?

For complementary IF, multiplex HAS1 with a marker identifying the scored cell population, such as adipocytes or peritubular cells, and examine cell borders separately from cytoplasm (HPA tissue IHC; standard IF practice). Choose a far-red fluorophore if the specimen has strong shorter-wavelength autofluorescence, and inspect an unstained section in each acquisition channel (standard IF practice). Set permeabilisation by epitope location: an intracellular epitope needs membrane access, whereas an extracellular loop can be tested without permeabilisation (UniProt Q92839 topology; standard IF practice). Interpret IF alongside the DAB result, accounting for HPA-supported plasma-membrane localisation in ICC/IF and broader cytoplasmic staining in tissue IHC (HPA subcellular; HPA tissue IHC).

Why is HAS1 DAB staining diffuse or present in negative regions?

The selected image used biotinylated goat anti-rabbit secondary antibody, an avidin-biotin complex and DAB, so include a no-primary control to locate detection-system background (datasheet A04784-1; standard IHC practice). Block endogenous peroxidase before chromogen development, and check endogenous biotin when staining follows tissue distribution rather than expected cells (standard chromogenic IHC practice). Reduce nonspecific staining by checking serum block, antibody concentration, washing and DAB development on matched serial sections (standard IHC practice). The caption reports a 10% goat-serum block, overnight primary incubation at 4°C and a 30-minute secondary incubation at 37°C (datasheet A04784-1).

How should I quantify HAS1 IHC across heterogeneous tissue? ⚠ ANSWER MARKED FOR VERIFICATION

Define the cell population and compartment before scoring, because HPA reports adipocyte, endothelial, smooth-muscle and extracellular-matrix staining (HPA tissue IHC). For cellular DAB, record percent positive cells and intensity categories 0–3, then calculate an H-score on a 0–300 scale if appropriate (standard IHC scoring practice). For sparse cells, count positive cells per mm² of viable tissue and report the assessed cell population as the denominator (standard digital pathology practice). Keep retrieval, staining batch, imaging settings and scoring threshold consistent across cases, and exclude folds, necrosis and tissue edges before comparing groups (standard IHC practice).

How can I distinguish genuine HAS1 staining from artefact?

A plausible result identifies defined cells and compartments: HPA reports adipocyte and peritubular-cell positivity, plus cytoplasmic staining in endothelial and smooth-muscle cells (HPA tissue IHC). Check whether DAB also follows plausible cell borders, since HAS1 is a 7-segment membrane enzyme with supported plasma-membrane localisation in ICC/IF (UniProt Q92839 topology; HPA subcellular). Treat isolated nuclear, necrotic, edge-only or vessel-wide brown signal cautiously, and use no-primary and peroxidase controls to investigate staining unrelated to specific antibody binding (standard IHC practice). HPA reports low consistency between antibody staining and RNA expression, so corroborate surprising cell-type patterns with an independent assay (HPA tissue IHC; standard validation practice).

Boster reagents

Best HAS1 / Hyaluronan synthase 1 IHC Antibodies

The catalog antibody has real IHC images from human mammary cancer, human lung cancer, and rat small intestine paraffin sections, plus IF images from U20S cells (catalog image captions).

Real IHC data

Anti-Hyaluronan synthase 1/HAS1 Antibody ®

Cat # A04784-1

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A04784-1 has IHC images from human mammary cancer, human lung cancer, and rat small intestine paraffin sections (catalog IHC captions). A04784-1 also has IF images from U20S cells and lists Human, Mouse, and Rat reactivity (catalog IF captions; catalog reactivity).

Which to pick: Choose A04784-1 for paraffin-section IHC: its IHC captions document citrate retrieval at pH 6 for 20 minutes and DAB detection; the fixative is unreported (catalog IHC captions). The same SKU lists IF and ICC and has IF images from U20S cells (catalog applications; catalog IF captions). For cross-species planning, it lists Human, Mouse, and Rat reactivity, while its IHC images document human and rat samples; clonality is unreported (catalog reactivity; catalog IHC captions; catalog clone field).

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

References

UniProt Consortium. UniProt entry Q92839 (HYAS1_HUMAN, Hyaluronan synthase 1).
Human Protein Atlas. HAS1 tissue IHC expression (reliability: Approved).
Human Protein Atlas. HAS1 subcellular location (ICC-IF): Mainly localized to the plasma membrane. In addition localized to the nucleoplasm..
Human Protein Atlas. HAS1 antibody validation summary (1 antibodies).
Clinicopathological Role of Serum-Derived Hyaluronan-Associated Protein (SHAP)-Hyaluronan Complex in Endometrial Cancer. Obstetrics and gynecology international 2011 — PMC3166775.
Exosomes derived from adipose-derived stem cells alleviate acute radiation-induced dermatitis through up-regulating hyaluronic acid synthase 1 expression. Stem cell research & therapy 2025 — PMC12093883.
Impact of Hyaluronic Acid on the Cutaneous T-Cell Lymphoma Microenvironment: A Novel Anti-Tumor Mechanism of Bexarotene. Cancers 2025 — PMC11764198.
Hyaluronan synthase 3 promotes plaque inflammation and atheroprogression. Matrix biology : journal of the International Society for Matrix Biology 2018 — PMC6023397.
PubMed PMID:8651928 — UniProt-cited evidence.
PubMed PMID:8798544 — UniProt-cited evidence.
PubMed PMID:15057824 — UniProt-cited evidence.