FADS2 / Acyl-CoA 6-desaturase · IHC design guide

Design Immunohistochemistry for FADS2

Plan FADS2 chromogenic IHC on paraffin sections using liver hepatocytes as a high-staining reference (HPA tissue IHC). This guide covers the catalog antibody’s 1:25 IHC-P dilution (datasheet), expected cytoplasmic staining (HPA tissue IHC), and interpretation in light of low staining–RNA consistency (HPA tissue IHC).

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

Immunohistochemistry protocol sheet for FADS2 (IHC for FADS2): expected localisation Cytoplasmic staining (HPA tissue IHC); ER membrane location (UniProt), antibody A01220-1, validated IHC image, and IHC protocol steps — Printable **FADS2** IHC protocol sheet — expected localisation Cytoplasmic staining (HPA tissue IHC); ER membrane location (UniProt), antibody A01220-1, controls and protocol steps. Open the full FADS2 IHC guide →

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FADS2 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 staining (HPA tissue IHC); ER membrane location (UniProt)
	Staining pattern	Cytoplasmic staining in most tissues (HPA tissue IHC)
	Antigen retrieval	Citrate pH 6.0 HIER, 95–98 °C, 20 min (rule: cytoplasmic / membrane antigen)
	Positive control ⓘ	Adrenal gland+4 more · see all
	Negative control ⓘ	Adipose tissue+4 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	Staining has low consistency with RNA expression (HPA tissue IHC)
	Regulation	Lower in breast tumors than normal tissue (UniProt)
	Isoform / epitope	Four isoforms; epitope coverage needs validation (UniProt)

Section 1

Recommended FADS2 IHC & IF Protocols

Compare the catalog antibody’s IHC-P protocol with published FADS2 IHC methods for osteosarcoma (PMC12214843) and esophageal biopsies (PMC9099135).

Recommended immunohistochemistry (IHC-P) protocol parameters
Sample	Paraffin-embedded tissue sections; fixative not specified (datasheet A01220-1; sample unspecified)
Fixation	Image fixative and duration unreported (datasheet A01220-1); 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-FADS2, 1:25 (datasheet A01220-1)
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	FADS2-positive staining in glandular cells of adrenal gland (HPA tissue IHC: High). HPA tissue profile: Cytoplasmic expression in most tissues. 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; UniProt O95864: ER membrane).

Section 2

What Is the Expected FADS2 Staining Pattern?

FADS2 is an endoplasmic reticulum membrane protein with four transmembrane segments, so expect predominantly cytoplasmic staining, potentially concentrated around the nucleus (UniProt O95864 topology; HPA subcellular). HPA reports cytoplasmic staining in most tissues, including high staining in hepatocytes and adrenal glandular cells (HPA tissue IHC). Treat intensity comparisons cautiously: HPA rates its tissue IHC profile Approved but reports low consistency between antibody staining and RNA expression (HPA tissue IHC).

What am I looking at on my slide?
Cytoplasmic staining in hepatocytes or adrenal glandular cells, with little nuclear signal.	This matches HPA's High staining in those cell types and its broad cytoplasmic profile (HPA tissue IHC). An ER-associated pattern is consistent with FADS2 topology (UniProt O95864); chromogenic IHC alone need not resolve individual ER membranes.
Strong signal confined to nuclei, with little cytoplasmic staining.	A nuclear-only pattern does not fit the reported ER membrane location (UniProt O95864; HPA subcellular). Review the counterstain and controls before calling it FADS2; HPA also reports nuclear membrane localization in ICC-IF, which is distinct from diffuse nuclear staining (HPA subcellular).
Prominent staining in adipocytes or lymph node germinal center cells.	HPA reports FADS2 as Not detected in these respective cell types (HPA tissue IHC). Check for antibody cross-reactivity or endogenous chromogenic activity before interpreting the signal; an HPA negative is a reference observation, not proof that every specimen must be negative.
Similar diffuse color across cells and surrounding tissue.	Uniform background obscures the cell-specific cytoplasmic pattern reported by HPA (HPA tissue IHC). Compare a control without primary antibody; nonspecific reagent binding or incomplete blocking can produce background in chromogenic IHC (standard IHC practice).
No staining in hepatocytes on an otherwise readable section.	Hepatocytes are reported High by HPA, making them a useful positive reference (HPA tissue IHC). A blank result warrants a check of the staining run and tissue quality before concluding FADS2 is absent; HPA's low RNA–staining consistency also limits certainty from a single specimen (HPA tissue IHC).

💡Expected FADS2 appearanceCall a result consistent with FADS2 when hepatocytes or adrenal glandular cells show clear, predominantly cytoplasmic staining at the reported High level (HPA tissue IHC; UniProt O95864); isolated diffuse nuclear signal or equally strong staining in HPA Not detected cell types should prompt a false-positive check (HPA subcellular; HPA tissue IHC).

How each factor affects the staining
Compartment and epitope orientation (UniProt O95864 topology).	FADS2 has four membrane spans and cytoplasmic and lumenal segments (UniProt O95864). Epitope position could affect access in a given assay (standard IHC practice), but no antibody epitope or target-specific retrieval response is supplied; do not infer one from topology.
Tissue and cell selection (HPA tissue IHC).	HPA reports High staining in several glandular populations and hepatocytes, Low staining in salivary and prostate glandular cells, and Not detected staining in adipocytes (HPA tissue IHC). Score the named cell population rather than treating the whole section as uniformly positive or negative.
Strength of tissue-pattern evidence (HPA tissue IHC; HPA antibodies).	HPA labels the tissue profile Approved while noting low antibody-staining versus RNA consistency (HPA tissue IHC). HPA006741 has Approved IHC status; the supplied HPA record does not give HPA079284 an IHC status (HPA antibodies). Use the tissue pattern as a reference, with controls.
Isoforms and processing (UniProt O95864).	UniProt lists four isoforms and a full-length 1–444 chain, without an annotated signal peptide, propeptide, or glycosylation site (UniProt O95864). These annotations do not establish which isoforms an antibody detects or predict its paraffin-section sensitivity; epitope coverage remains unspecified.

Why is my staining missing, weak or wrong?
Situation	Likely cause	Next action
Positive-reference liver has no hepatocyte signal (HPA tissue IHC).	The result conflicts with HPA's High hepatocyte staining, but the record does not identify a target-specific cause (HPA tissue IHC).	Check section integrity, primary-antibody addition, detection reagents, and a run control; review the antibody's IHC-P instructions for retrieval and dilution (standard IHC practice). Avoid assigning a FADS2 fixation effect without evidence.
Staining is mostly nuclear rather than cytoplasmic.	Diffuse nuclear staining is discordant with ER membrane FADS2 and HPA's cytoplasmic tissue profile (UniProt O95864; HPA tissue IHC).	Compare nuclear counterstain and a control without primary antibody; assess whether signal is truly intranuclear or outlines the nuclear membrane (standard IHC practice; HPA subcellular).
Adipocytes or lymph node germinal center cells stain strongly.	Those cells are listed as Not detected in HPA tissue IHC; cross-reactivity or endogenous detection activity is possible (HPA tissue IHC; standard IHC practice).	Compare a control without primary antibody and the expected positive cell population in the same run; evaluate background before scoring the unexpected cells (standard IHC practice).
Brown precipitate appears broadly across the section.	Diffuse deposit can arise from nonspecific binding or residual endogenous chromogenic activity (standard IHC practice). It does not resemble HPA's cell-associated cytoplasmic profile (HPA tissue IHC).	Inspect the control without primary antibody, blocking, washes, and the chromogenic detection step; interpret only signal distinguishable from background (standard IHC practice).
Only faint staining appears in salivary or prostate glandular cells.	HPA records Low staining in these populations, so weak signal can match the reference (HPA tissue IHC). Its Approved profile also carries a low RNA–staining consistency warning (HPA tissue IHC).	Compare cells within the section and a High reference tissue, such as liver, processed in the same run; score intensity in the specified cells (HPA tissue IHC; standard IHC practice).
Q: Does ICC-IF show the same localization as tissue IHC?	HPA reports the ER as the main approved ICC-IF location, with additional approved nuclear and plasma membrane locations (HPA subcellular). Tissue IHC is described mainly as cytoplasmic (HPA tissue IHC).	A: Use the ER-centered ICC-IF pattern as a localization cross-check, while interpreting paraffin-section chromogenic staining by its tissue and cell pattern; the ICC-IF record does not establish an IHC-P protocol (HPA subcellular; HPA tissue IHC).

Source: UniProt O95864 Human Protein Atlas tissue Human Protein Atlas subcellular

Experiment evidence

IHC & IF images showing FADS2 staining

Immunohistochemical analysis of paraffin-embedded H.brain section using FADS2 Antibody (Center). A01220-1 was diluted at 1:25 dilution. A peroxidase-conjugated goat anti-rabbit IgG at 1:400 dilution was used as the secondary antibody, followed by DAB staining.

A01220-1 · IHCImmunohistochemical analysis of paraffin-embedded H.brain section using FADS2 Antibody (Center). A01220-1 was diluted at 1:25 dilution. A pe

HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000134824-FADS2/tissue/cerebral+cortex#imid_2241368

HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000134824-FADS2/tissue/colon#imid_2241286

HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000134824-FADS2/tissue/liver#imid_2241287

HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000134824-FADS2/tissue/kidney#imid_2241288

HPA · ICC-IF AF22Human Protein Atlas immunofluorescence, AF22, antibody HPA006741; green = FADS2, blue = nucleus, red = microtubules.

← swipe / scroll for more images →

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

Sample controls for FADS2 IHC & IF

🧪Run duodenum first and expect staining in its glandular cells (HPA: High in duodenal glandular cells). Use adipose tissue as the negative tissue, with adipocytes showing no specific staining (HPA: Not detected in adipocytes); on the duodenum slide, assess surrounding nonglandular cells for background without assuming they are FADS2-negative.

Positive control tissue: Adrenal gland (Glandular cells, HPA High)

Negative control tissue: Adipose tissue (HPA Not detected)

ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show FADS2 in AF22, HBEC3-KT, HEL, A-549, HAP1, with annotated localisation: Endoplasmic reticulum (approved) (HPA subcellular).

Technical controls: Include a no-primary, secondary-only control and an isotype control matched to the primary antibody’s host species and immunoglobulin class, alongside FADS2 knockout material if available (standard IHC controls). For duodenum, block and check endogenous peroxidase before interpreting DAB staining in glandular cells (standard chromogenic IHC practice; HPA: High in duodenal glandular cells).

⚠️Feasibility: A target-specific fixation window or fixation effect is unreported in the supplied evidence, and the selected A01220-1 paraffin-section caption does not report a fixative (selected tissue-IHC caption). Retrieval dependency is also unreported; optimize antigen retrieval empirically for IHC-P (standard IHC practice). Frozen sections or IF cannot be judged easier from this evidence; if using IF, assess expected endoplasmic-reticulum localization and check tissue autofluorescence (HPA: Endoplasmic reticulum, approved; standard IF practice).

HPA tissue IHC evidence for FADS2

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
Adrenal gland	Glandular cells	High	Protein (IHC)	HPA →
Appendix	Glandular cells	High	Protein (IHC)	HPA →
Cerebellum	Purkinje cells	High	Protein (IHC)	HPA →
Duodenum	Glandular cells	High	Protein (IHC)	HPA →
Epididymis	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 →
Lymph node	Germinal center cells	Not detected	Protein (IHC)	HPA →
Ovary	Ovarian stroma cells	Not detected	Protein (IHC)	HPA →
Parathyroid gland	Glandular cells	Not detected	Protein (IHC)	HPA →
Soft tissue	Fibroblasts	Not detected	Protein (IHC)	HPA →

Section 3

Advanced FADS2 IHC Tips

Troubleshoot FADS2 chromogenic IHC in paraffin sections using compartment, cell type, and control patterns; IF/ICC considerations are covered separately.

How should I retrieve FADS2 when staining paraffin sections?

Begin with citrate buffer at pH 6.0, heated to 95–98 °C for 20 min (page retrieval rule). Let sections cool consistently before washing, and keep section thickness and staining conditions matched across comparisons (standard IHC practice). If staining is weak, test a separately controlled retrieval condition while retaining the stated citrate condition as the reference (standard IHC practice). Compare cytoplasmic staining in hepatocytes or cerebellar Purkinje cells with matched negative controls, since those cells show high tissue staining (HPA tissue IHC). Excessively diffuse staining or damaged tissue after retrieval calls for checking section integrity and detection background before increasing primary antibody concentration (standard IHC practice).

Could fixation explain weak or variable FADS2 staining?

FADS2 specific fixation sensitivity is unknown: the selected paraffin brain caption does not state its fixative (A01220-1 caption). Record fixative, fixation duration, processing, and section age for every specimen, then compare specimens processed alike (standard IHC practice). If fixation differs between groups, assess staining in matched reference tissue before treating intensity differences as biological (standard IHC practice). Keep the page’s citrate pH 6.0, 95–98 °C, 20 min retrieval constant during that comparison (page retrieval rule). The demonstrated brain section used primary antibody at 1:25, but its result cannot establish which fixative or fixation duration preserves FADS2 staining (A01220-1 caption).

Which staining pattern fits FADS2 in tissue sections?

Expect predominantly cytoplasmic staining at light microscope resolution because FADS2 is an endoplasmic reticulum membrane protein (UniProt O95864 localisation; HPA tissue IHC). HPA also reports approved nuclear membrane and plasma membrane locations, so assess those patterns alongside the dominant endoplasmic reticulum signal (HPA subcellular). Four predicted membrane spans place large regions on the cytoplasmic side, making a purely nuclear interior pattern difficult to reconcile with the annotated topology (UniProt O95864 topology). Examine whether signal follows cells rather than section edges, debris, or empty spaces (standard IHC practice). Use the same counterstain and imaging settings when comparing compartments, and inspect a no-primary control for chromogen deposition (standard IHC practice).

How can epitope position affect FADS2 IHC interpretation?

FADS2 has 4 annotated isoforms, while the supplied IHC caption gives no epitope coordinates or isoform coverage (UniProt O95864 isoforms; A01220-1 caption). Ask which sequence the antibody recognizes before claiming that a staining change belongs to a particular isoform (standard IHC practice). The annotated protein has 4 transmembrane spans and cytoplasmic regions at residues 1–131, 179–264, and 327–444 (UniProt O95864 topology). Epitope accessibility can vary with processing and retrieval, so compare the same retrieval condition across specimens (standard IHC practice). Treat compartment and intensity changes as antibody staining observations until epitope information and independent specificity evidence support a narrower interpretation (standard IHC practice).

How should I check a FADS2 result by multiplex IF?

On the separate IF/ICC workflow, pair FADS2 with a marker identifying the expected cell population, such as hepatocytes in liver or Purkinje cells in cerebellum (HPA tissue IHC; standard IF practice). Choose spectrally separated fluorophores after inspecting unstained tissue autofluorescence, and collect single stain controls for bleed through (standard IF practice). Match permeabilisation to the mapped epitope: the cytoplasmic regions at residues 1–131, 179–264, and 327–444 require intracellular access, while short lumenal regions require access across the endoplasmic reticulum membrane (UniProt O95864 topology; standard IF practice). Compare the resulting pattern with an endoplasmic reticulum marker and a no-primary control, without carrying the paraffin IHC dilution into IF (HPA subcellular; standard IF practice).

How do I reduce diffuse DAB background without losing FADS2 signal?

Start with a no-primary control and inspect whether brown deposit appears outside cellular structures (standard IHC practice). The selected paraffin brain image used FADS2 antibody at 1:25, peroxidase-conjugated secondary at 1:400, and DAB detection; these are image-specific conditions, not a universal optimum (A01220-1 caption). Block endogenous peroxidase before detection, control nonspecific binding, and wash thoroughly between incubations (standard chromogenic IHC practice). If background persists, titrate the primary and secondary while keeping retrieval at citrate pH 6.0, 95–98 °C, 20 min for the initial comparison (page retrieval rule; standard IHC practice). Score cell-associated signal only after confirming that the negative control remains clear (standard IHC practice).

What should I measure when comparing FADS2 staining between sections? ⚠ ANSWER MARKED FOR VERIFICATION

Define the scored cell population and compartment before measuring DAB intensity, since FADS2 is mainly associated with the endoplasmic reticulum and HPA reports cytoplasmic tissue staining (UniProt O95864 localisation; HPA tissue IHC). An H-score combines the percentage of cells at each intensity; alternatively report percentage positive cells or positive cell density per mm² (standard IHC practice). Normalize counts to the number of eligible cells or measured viable tissue area, and apply identical thresholds across groups (standard IHC practice). Exclude folds, edges, and necrotic areas using prespecified rules (standard IHC practice). Report cell type alongside the score because HPA shows high hepatocyte staining but no detectable adipocyte staining (HPA tissue IHC).

When should I doubt an apparent FADS2 positive result?

A credible result should be cell-associated and largely cytoplasmic, consistent with FADS2 at the endoplasmic reticulum membrane (HPA tissue IHC; UniProt O95864 localisation). Check the claimed cell type: HPA reports high staining in hepatocytes and cerebellar Purkinje cells, but no detectable staining in adipocytes or lymph node germinal center cells (HPA tissue IHC). Be cautious with isolated nuclear interior staining, section-edge gradients, necrotic deposits, or signal reproduced in a no-primary control (UniProt O95864 topology; standard IHC practice). Endogenous peroxidase can also produce misleading DAB signal, so assess a blocked detection control (standard chromogenic IHC practice). Interpret intensity differences cautiously because HPA labels its tissue staining approved while reporting low consistency with RNA expression (HPA tissue IHC).

Boster reagents

Best FADS2 / Acyl-CoA 6-desaturase IHC Antibodies

The catalog includes one human-reactive anti-FADS2 antibody with a DAB IHC image from a paraffin-embedded brain section (catalog: A01220-1; image caption). No IF image is supplied (catalog: A01220-1).

Real IHC data Immunohistochemical analysis of paraffin-embedded H.brain section using FADS2 Antibody (Center). A01220-1 was diluted at 1:25 dilution. A peroxidase-conjugated goat anti-rabbit IgG at 1:400 dilution was used as the secondary antibody, followed by DAB staining.

Anti-FADS2 Antibody (Center)

Cat # A01220-1

View product →

A01220-1 will render with its human brain paraffin-section IHC image, showing 1:25 primary dilution and DAB detection (image caption). Its listed applications include IHC-P, flow cytometry and WB; reactivity is listed as human (catalog: A01220-1).

Which to pick: Choose A01220-1 for human paraffin-section IHC: it is a rabbit polyclonal antibody listed for IHC-P, with a brain-section IHC image (catalog: A01220-1; image caption). The caption does not report the fixative (image caption). There is no IF/ICC application or image, or nonhuman reactivity, in this catalog entry, so it does not establish an IF/ICC or cross-species choice (catalog: A01220-1).

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

References

UniProt Consortium. UniProt entry O95864 (FADS2_HUMAN, Acyl-CoA 6-desaturase).
Human Protein Atlas. FADS2 tissue IHC expression (reliability: Approved).
Human Protein Atlas. FADS2 subcellular location (ICC-IF): Mainly localized to the endoplasmic reticulum. In addition localized to the nuclear membrane and plasma membrane..
Human Protein Atlas. FADS2 antibody validation summary (2 antibodies).
The role of fatty acid desaturase 2 in multiple tumor types revealed by bulk and single-cell transcriptomes. Lipids in health and disease 2023 — PMC9930218.
Integrated multi-omics demonstrates enhanced antitumor efficacy of donafenib combined with FADS2 inhibition in hepatocellular carcinoma. Translational oncology 2025 — PMC11615612.
Leveraging diverse cell death patterns in osteosarcoma patients and identification of the function of FADS2 in osteosarcoma cells. Scientific reports 2025 — PMC12214843.
Elevation of fatty acid desaturase 2 in esophageal adenocarcinoma increases polyunsaturated lipids and may exacerbate bile acid-induced DNA damage. Clinical and translational medicine 2022 — PMC9099135.
PubMed PMID:9867867 — UniProt-cited evidence.
PubMed PMID:10860662 — UniProt-cited evidence.
PubMed PMID:14702039 — UniProt-cited evidence.