SAR1A / Small COPII coat GTPase SAR1A · IHC design guide

Design Immunohistochemistry for SAR1A

Plan SAR1A paraffin IHC around cytoplasmic staining, with lung macrophages or colon glandular cells as high-staining references (HPA tissue IHC). Use the catalog antibody’s 1:10–1:50 starting range for chromogenic IHC (datasheet: IHC-P), and interpret staining cautiously because the HPA antibody may detect protein from more than one gene (HPA tissue IHC).

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

Immunohistochemistry protocol sheet for SAR1A (IHC for SAR1A): expected localisation Ubiquitous cytoplasmic tissue staining (HPA tissue IHC), antibody A07224-1, validated IHC image, and IHC protocol steps — Printable **SAR1A** IHC protocol sheet — expected localisation Ubiquitous cytoplasmic tissue staining (HPA tissue IHC), antibody A07224-1, controls and protocol steps. Open the full SAR1A IHC guide →

Navigate to: Protocols Staining pattern Controls Antibodies

SAR1A 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	Ubiquitous cytoplasmic tissue staining (HPA tissue IHC)
	Staining pattern	Cytoplasmic staining across many cell types (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 ⓘ	Ovary+1 more · see all

Important caveats

Reasons your staining may differ from the expected pattern.

	Fixation	Use formalin-fixed paraffin sections (selected-SKU IHC image A07224-1); Matched tissue-IHC evidence does not establish the fixation claim. Validate the specimen-specific method before use. (selected-SKU IHC image A07224-1)
	Caveat	Staining may include protein from more than one gene (HPA tissue IHC)
	Regulation	Expression regulation not annotated (UniProt)
	Isoform / epitope	2 isoforms; epitope coverage is unknown (UniProt; datasheet)

Section 1

Recommended SAR1A IHC & IF Protocols

The catalog antibody’s IHC-P protocol is complemented by published SAR1A IHC methods for paraffin-embedded cells (PMC9746051) and FFPE tissue sections (PMC11541848).

Recommended immunohistochemistry (IHC-P) protocol parameters
Sample	FFPE human lung carcinoma tissue (datasheet A07224-1)
Fixation	Image formalin-fixed; duration unreported (datasheet A07224-1); 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-SAR1A, 1:10-1:50 (datasheet A07224-1)
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	SAR1A-positive staining in glandular cells of adrenal gland (HPA tissue IHC: High). HPA tissue profile: Ubiquitous cytoplasmic expression. No signal in the no-primary control.

💡Decision noteStart with citrate pH 6.0 heat retrieval at 95–98 °C for 20 min for this cytoplasmic and membrane-associated target (page retrieval rule; UniProt Q9NR31 localization).

Section 2

What Is the Expected SAR1A Staining Pattern?

SAR1A acts at endoplasmic reticulum exit sites and also associates with Golgi, cytosol and, under leucine deprivation, lysosomal membranes (UniProt Q9NR31). Expect predominantly cytoplasmic IHC staining, especially in HPA high expressing glandular cells, lung macrophages and placental endothelial cells (HPA tissue IHC). SAR1A has no transmembrane segment (UniProt Q9NR31 topology). HPA calls the tissue pattern Supported, with medium consistency against RNA data and a warning that the staining may represent protein from more than one gene (HPA tissue IHC).

What am I looking at on my slide?
Cytoplasmic staining in colon or duodenum glandular cells, with a localized perinuclear component.	This fits HPA high staining in those cells and UniProt ER/Golgi localization (HPA tissue IHC; UniProt Q9NR31). A perinuclear accent is plausible, but routine chromogenic IHC alone cannot assign individual puncta to ER exit sites (general IHC practice).
Predominantly nuclear staining, or signal confined to extracellular material.	Neither is an expected principal SAR1A compartment (UniProt Q9NR31 subcellular location; HPA tissue IHC). Check the no-primary control and the distribution across cells before treating the signal as specific (general IHC practice).
Strong staining in ovarian stroma or smooth muscle cells while the chosen positive control behaves as expected.	HPA reports these cell types as not detected; cross-reactivity or endogenous chromogen activity is possible (HPA tissue IHC; general IHC practice). HPA also flags possible detection of protein from more than one gene, so this pattern cannot establish SAR1A specificity (HPA tissue IHC).
Diffuse color over cells, stroma and blank areas, with little compartment contrast.	This distribution is less consistent with the reported cytoplasmic profile (HPA tissue IHC). Background from detection reagents, inadequate blocking or washing, or overly strong development should be assessed with controls (general IHC practice).
No staining in pancreatic exocrine glandular cells or lung macrophages.	Both are HPA high cell types, so an absent signal raises a technical concern (HPA tissue IHC). First verify that the correct cells are present, then review antibody and detection controls; one negative section cannot establish absent SAR1A expression (general IHC practice).

💡Expected SAR1A appearanceCall a section positive when the expected cell type shows clear, mainly cytoplasmic staining against a clean background—potentially strong in HPA high cell types—while isolated nuclear, extracellular or widespread control staining argues against a specific result (HPA tissue IHC; UniProt Q9NR31; general IHC practice).

How each factor affects the staining
Tissue and cell choice	Colon, duodenum, adrenal and epididymal glandular cells; pancreatic exocrine glandular cells; lung macrophages; and placental endothelial cells are HPA high examples (HPA tissue IHC). Ovarian stroma and smooth muscle cells are reported as not detected, while oral squamous cells are low (HPA tissue IHC).
Subcellular interpretation	ER exit sites, ER and Golgi association support a cytoplasmic pattern; the protein has no transmembrane segment (UniProt Q9NR31). Chromogenic morphology cannot prove which organelle produces a particular focus (general IHC practice).
Antibody specificity and isoforms	HPA rates the tissue pattern Supported but cautions that antibodies may detect protein from more than one gene (HPA tissue IHC). UniProt lists 2 isoforms; the supplied evidence does not identify an isoform-specific IHC epitope (UniProt Q9NR31).
IF/ICC: where should signal appear?	HPA reports supported ER localization in ICC-IF and lists images from A-431, U-251MG and U2OS (HPA subcellular). Treat that as a compartment reference; IF/ICC methods belong to the separate guide (HPA subcellular).

Why is my staining missing, weak or wrong?
Situation	Likely cause	Next action
Expected high cell type is blank.	A failed staining run, absent target cells in the section, or an ineffective detection step is possible (general IHC practice).	Confirm the cell type on the counterstain; compare another HPA high control and review primary-antibody and detection controls (HPA tissue IHC; general IHC practice).
Ovarian stroma or smooth muscle cells stain strongly.	These cells are HPA not detected; cross-reactivity or endogenous detection activity may contribute (HPA tissue IHC; general IHC practice).	Compare a no-primary control and an expected positive cell type; assess endogenous peroxidase blocking for chromogenic detection (general IHC practice).
Staining is mainly nuclear.	The compartment conflicts with the reported cytoplasmic tissue pattern and ER-centered localization (HPA tissue IHC; UniProt Q9NR31).	Review the no-primary control, cell boundaries and counterstain; avoid scoring nuclear color as SAR1A without independent support (general IHC practice).
Brown signal covers tissue and empty slide areas.	Nonspecific detection background or excessive chromogen development is possible (general IHC practice).	Inspect no-primary and reagent controls; review blocking, washes and development time before interpreting cell intensity (general IHC practice).
Positive cells show weak, hard-to-localize color.	Target-specific fixation effects are not established by the supplied assay evidence. Verify with a matched IHC source before attributing a result to fixation.	Compare a HPA high control; review the antibody's validated IHC-P conditions and routine retrieval and detection controls without assuming a SAR1A-specific fixation effect (HPA tissue IHC; general IHC practice).
Several cell types stain, but their rank order differs from HPA.	HPA describes ubiquitous cytoplasmic expression and low RNA tissue specificity; its IHC consistency is medium and it warns of possible detection from more than one gene (HPA tissue IHC).	Score the named cell populations separately, compare matched positive and not-detected examples, and report discordance as uncertain rather than assigning it to SAR1A alone (HPA tissue IHC; general IHC practice).

Source: UniProt Q9NR31 Human Protein Atlas tissue Human Protein Atlas subcellular

Experiment evidence

IHC & IF images showing SAR1A staining

Formalin-fixed and paraffin-embedded human lung carcinoma with SAR1A Antibody (Center), which was peroxidase-conjugated to the secondary antibody, followed by DAB staining. This data demonstrates the use of this antibody for immunohistochemistry; clinical relevance has not been evaluated.

A07224-1 · IHCFormalin-fixed and paraffin-embedded human lung carcinoma with SAR1A Antibody (Center), which was peroxidase-conjugated to the secondary ant

HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000079332-SAR1A/tissue/cerebral+cortex#imid_5692788

HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000079332-SAR1A/tissue/colon#imid_5692730

HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000079332-SAR1A/tissue/liver#imid_5692731

HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000079332-SAR1A/tissue/kidney#imid_5692716

HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody CAB022545; green = SAR1A, blue = nucleus, red = microtubules.

← swipe / scroll for more images →

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

Sample controls for SAR1A IHC & IF

🧪Run colon first: glandular cells should stain (HPA: High in colon glandular cells). Use smooth muscle as the negative tissue; if the colon section includes muscularis, its smooth muscle cells should lack specific staining and serve as an internal negative reference (HPA: Not detected in smooth muscle cells).

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

Negative control tissue: Ovary (HPA Not detected)

ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show SAR1A in A-431, U-251MG, U2OS, with annotated localisation: Endoplasmic reticulum (supported) (HPA subcellular).

Technical controls: Include a no-primary, secondary-only control; a host-species- and isotype-matched irrelevant antibody that matches the primary antibody’s monoclonal or polyclonal format; and SAR1A-knockout material as a biological negative when available (standard IHC practice). For colon, quench endogenous peroxidase and check for endogenous biotin if using avidin–biotin detection (standard IHC practice).

⚠️Feasibility: The selected antibody caption documents formalin-fixed, paraffin-embedded lung carcinoma stained with peroxidase/DAB, but reports no target-specific fixation window or fixation effect (caption: A07224-1). Retrieval dependence is unreported, and the supplied evidence does not establish whether frozen sections or IF would be easier; ICC-IF images support ER localization (HPA: subcellular). In colon, endogenous biotin can complicate avidin–biotin chromogenic detection (standard IHC practice).

HPA tissue IHC evidence for SAR1A

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

Positive expression · recommended positive controls

Tissue	Cell type	Level	Evidence	Source
Adrenal gland	Glandular cells	High	Protein (IHC)	HPA →
Colon	Glandular cells	High	Protein (IHC)	HPA →
Duodenum	Glandular cells	High	Protein (IHC)	HPA →
Epididymis	Glandular cells	High	Protein (IHC)	HPA →
Lung	Macrophages	High	Protein (IHC)	HPA →

Undetected expression · recommended negative controls

Tissue	Cell type	Level	Evidence	Source
Ovary	Ovarian stroma cells	Not detected	Protein (IHC)	HPA →
Smooth muscle	Smooth muscle cells	Not detected	Protein (IHC)	HPA →

Section 3

Advanced SAR1A IHC Tips

Troubleshoot SAR1A staining in paraffin sections by checking retrieval, compartment, controls and scoring before interpreting chromogenic signal.

What retrieval should I try when SAR1A staining is weak in paraffin sections?

For SAR1A IHC on paraffin sections, start with citrate pH 6.0 HIER at 95–98 °C for 20 min (page retrieval setting). Compare a retrieved section with an otherwise matched section to see whether retrieval improves cytoplasmic signal without increasing diffuse background (standard IHC practice; HPA tissue IHC: ubiquitous cytoplasmic expression). Keep section thickness, antibody incubation and DAB development consistent across that comparison (standard IHC practice). If staining remains weak, optimise heating and cooling within the citrate workflow before considering another buffer as a fallback (standard IHC practice). Evaluate any gain against tissue morphology and negative controls, since stronger colour alone does not establish SAR1A specificity (standard IHC practice).

How should I troubleshoot variable SAR1A staining across differently fixed IHC specimens?

The selected A07224-1 tissue image used formalin-fixed, paraffin-embedded human lung carcinoma, but it provides no comparison of fixation conditions (A07224-1 caption). SAR1A-specific sensitivity to fixation is therefore unknown; do not infer a preferred fixation duration from its localisation or phosphorylation record (UniProt Q9NR31; A07224-1 caption). Record fixation and processing history for each specimen, then compare sections processed and stained together (standard IHC practice). If staining varies, inspect morphology and include a consistent reference section in each run before attributing the difference to SAR1A abundance (standard IHC practice). Apply the same citrate pH 6.0, 20 min retrieval setting during that comparison (page retrieval setting).

Which compartments should show credible SAR1A staining in chromogenic IHC?

Expect predominantly cytoplasmic staining in tissue sections, consistent with the reported ubiquitous cytoplasmic IHC profile (HPA tissue IHC). SAR1A acts at endoplasmic reticulum exit sites and is also annotated at Golgi membranes and in cytosol; its membrane association need not appear as a sharp cell-surface outline (UniProt Q9NR31). Supported subcellular imaging places it at the endoplasmic reticulum (HPA subcellular). Examine intact cells at sufficient magnification to distinguish cytoplasmic colour from pigment, extracellular precipitate or nuclear counterstain (standard IHC practice). If staining appears exclusively nuclear or extracellular, repeat the run with controls before assigning that pattern to SAR1A (UniProt Q9NR31 topology; standard IHC practice).

Can this IHC stain distinguish SAR1A isoforms or exclude SAR1B recognition?

SAR1A has 2 annotated isoforms, while the supplied A07224-1 caption does not define the antibody epitope or demonstrate isoform selectivity (UniProt Q9NR31; A07224-1 caption). The HPA tissue assessment explicitly cautions that its staining targets protein from more than one gene, so its pattern alone cannot establish SAR1A-only recognition (HPA tissue IHC). Check the catalog antibody’s immunogen and validation record before making isoform or paralog claims (standard IHC practice). If specificity is central to the experiment, compare staining after a SAR1A-specific perturbation with an independently validated antibody or another orthogonal readout (standard IHC practice). Report unresolved cross-reactivity when interpreting shared cytoplasmic staining (HPA tissue IHC).

How should I adapt SAR1A staining for multiplex IF on tissue sections?

Use the IF/ICC guide for the fluorescence workflow; the A07224-1 tissue image documents chromogenic IHC with a peroxidase-conjugated secondary antibody and DAB (A07224-1 caption). Multiplex SAR1A with a validated marker for the cell population being evaluated, such as a macrophage marker when examining lung macrophages (HPA tissue IHC: High in lung macrophages; standard IF practice). Choose spectrally separated fluorophores after checking tissue autofluorescence and include single-stain controls for bleed-through (standard IF practice). Because SAR1A has no transmembrane segment, set permeabilisation according to the mapped epitope’s accessibility and the antibody’s IF validation, rather than assuming a membrane-facing epitope (UniProt Q9NR31 topology; standard IF practice).

How can I separate SAR1A signal from diffuse DAB background?

First compare the stained section with a matched no-primary control and check whether colour follows intact cell cytoplasm rather than folds, edges or extracellular deposits (standard IHC practice; HPA tissue IHC: cytoplasmic expression). Include a peroxidase block before DAB detection and assess whether residual endogenous enzyme activity contributes to colour (standard chromogenic IHC practice). If background persists, adjust blocking and washes, then optimise the antibody concentration using its documented range rather than assuming a new dilution (standard IHC practice). Keep DAB development comparable across sections and inspect the negative control at the same exposure (standard IHC practice). Strong colour in necrotic regions should be excluded from SAR1A scoring (standard IHC practice).

How should I quantify heterogeneous SAR1A staining in IHC sections? ⚠ ANSWER MARKED FOR VERIFICATION

Define the cell population and region before scoring, since HPA reports high staining in lung macrophages and several glandular or endothelial populations (HPA tissue IHC). For cell-level scoring, record the percentage of positive eligible cells and an intensity-based H-score using prespecified thresholds (standard IHC practice). If counting stained cells spatially, report their density per mm² of viable tissue or of the defined compartment (standard IHC practice). Normalise comparisons to the same eligible cell type or tissue area, with matched retrieval, detection and DAB development across runs (standard IHC practice). Exclude necrosis, section edges and technical artefacts before calculating scores (standard IHC practice).

When is an apparent SAR1A-positive IHC pattern likely to be artefactual?

Treat staining in intact cytoplasm as more plausible than isolated nuclear, extracellular or cell-surface-only colour, given the tissue IHC profile and SAR1A localisation record (HPA tissue IHC; UniProt Q9NR31). Check that the positive cells match the annotated population before comparing regions; lung macrophages can stain strongly (HPA tissue IHC: High in lung macrophages). Colour concentrated at section edges, folds or necrotic areas warrants review with a matched no-primary control (standard IHC practice). Persistent DAB colour in that control suggests background or endogenous peroxidase activity (standard chromogenic IHC practice). Even a plausible pattern does not prove SAR1A specificity, because the HPA tissue assessment warns of recognition of protein from more than one gene (HPA tissue IHC).

Boster reagents

Best SAR1A / Small COPII coat GTPase SAR1A IHC Antibodies

One human-reactive anti-SAR1A antibody has real IHC data from formalin-fixed, paraffin-embedded human lung carcinoma; no IF/ICC data are supplied (catalog: A07224-1 applications and image caption).

Real IHC data Formalin-fixed and paraffin-embedded human lung carcinoma with SAR1A Antibody (Center), which was peroxidase-conjugated to the secondary antibody, followed by DAB staining. This data demonstrates the use of this antibody for immunohistochemistry; clinical relevance has not been evaluated.

Anti-SAR1A Antibody (Center)

Cat # A07224-1

View product →

A07224-1 is the only card and is listed for human IHC-P (catalog: A07224-1 applications and reactivity). Its image shows DAB staining of formalin-fixed, paraffin-embedded human lung carcinoma (catalog: A07224-1 image caption).

Which to pick: Choose A07224-1 for human tissue IHC-P; it is a rabbit polyclonal antibody with a listed IHC-P dilution of 1:10–1:50, and its own image documents formalin-fixed, paraffin-embedded human lung carcinoma (catalog: A07224-1 host, dilution, applications, and image caption). No listed SKU is validated for IF/ICC or species beyond human, so this catalog does not support an IF/ICC or cross-species pick (catalog: A07224-1 applications, reactivity, and IF image list).

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

References

UniProt Consortium. UniProt entry Q9NR31 (SAR1A_HUMAN, Small COPII coat GTPase SAR1A).
Human Protein Atlas. SAR1A tissue IHC expression (reliability: Supported).
Human Protein Atlas. SAR1A subcellular location (ICC-IF): Localized to the endoplasmic reticulum..
Human Protein Atlas. SAR1A antibody validation summary (3 antibodies).
SAR1A regulates the RhoA/YAP and autophagy signaling pathways to influence osteosarcoma invasion and metastasis. Cancer science 2022 — PMC9746051.
SAR1A Induces Cell Growth and Epithelial-Mesenchymal Transition Through the PI3K/AKT/mTOR Pathway in Head and Neck Squamous Cell Carcinoma: An In Vitro and In Vivo Study. Biomedicines 2024 — PMC11591717.
Molecular analysis and intestinal expression of SAR1 genes and proteins in Anderson's disease (Chylomicron retention disease). Orphanet journal of rare diseases 2011 — PMC3029219.
Comprehensive Proteomic Analysis Reveals Distinct Features and a Diagnostic Biomarker Panel for Early Pregnancy Loss in Histological Subtypes. Molecular & cellular proteomics : MCP 2024 — PMC11541848.
PubMed PMID:10871277 — UniProt-cited evidence.
PubMed PMID:11230166 — UniProt-cited evidence.
PubMed PMID:14702039 — UniProt-cited evidence.