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APLNR / Apelin receptor · IHC design guide
Design Immunohistochemistry for APLNR
Plan paraffin-section APLNR IHC with the catalog antibody at 1:100–1:300 (datasheet: A05042). Assess cytoplasmic tissue staining in the context of APLNR’s expected membrane location and ligand-driven internalization (HPA tissue IHC; UniProt).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
APLNR 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 | Cell membrane expected (UniProt); cytoplasmic tissue staining observed (HPA tissue IHC) | |
| Staining pattern | Cytoplasmic staining in several tissues, including glia and cardiomyocytes (HPA tissue IHC) | |
| Antigen retrieval | Citrate pH 6.0 HIER, 95–98 °C, 20 min (rule: cytoplasmic / membrane antigen) | |
| Positive control | Caudate+4 more · see all | |
| Negative control | Adipose tissue+4 more · see all |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Keep fixation consistent across sections. (standard IHC practice; not target-specific) | |
| Caveat | Tissue staining has low consistency with RNA expression (HPA tissue IHC) | |
| Regulation | Ligand exposure shifts APLNR from the surface to endosomes (UniProt) | |
| Isoform / epitope | No isoforms annotated; extracellular versus cytoplasmic epitope matters (UniProt) |
Section 1
Recommended APLNR IHC & IF Protocols
The catalog antibody’s IHC-P protocol is accompanied by 4 published APLNR immunohistochemistry protocols from the listed PMC articles.
| Sample | Paraffin-embedded Human breast cancer tissue; fixative not specified (datasheet A05042) |
| Fixation | Image fixative and duration unreported (datasheet A05042); 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-APLNR, 1:100-1:300 (datasheet A05042) |
| 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 | APLNR-positive staining in neuronal cells of caudate (HPA tissue IHC: Medium). HPA tissue profile: Cytoplasmic expression in several 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 specification); adjust for the antibody and tissue used.
Section 2
What Is the Expected APLNR Staining Pattern?
APLNR is a seven-pass cell-membrane receptor that can enter a recycling endosomal compartment after ligand exposure (UniProt P35414 topology and subcellular location). In paraffin-section IHC, expect staining in selected cells, including cardiomyocytes, cortical or hippocampal glia, and caudate neurons (HPA tissue IHC: Medium). HPA also describes cytoplasmic staining across several tissues, but rates its IHC evidence Approved with low consistency between staining and RNA expression (HPA tissue IHC).
| Selective membrane-associated staining, with some cytoplasmic signal, in heart cardiomyocytes or cortical glia. | This fits the receptor's membrane location and possible endosomal recycling (UniProt P35414 subcellular location), and the reported Medium staining in these cells (HPA tissue IHC). HPA describes a broader cytoplasmic pattern, so membrane-only staining is not required for a plausible result (HPA tissue IHC). Judge the cellular pattern alongside a negative control. |
| Predominantly nuclear staining, or signal confined to a compartment unrelated to membrane or cytoplasm. | Nuclear localisation is unsupported by the supplied receptor record (UniProt P35414 subcellular location; HPA tissue IHC). Treat this pattern as suspect: compare control sections, counterstain, and cellular boundaries before interpreting it as APLNR. Neither source establishes a target-specific fixation effect, so the compartment alone cannot identify the technical cause. |
| Strong staining in an unexpected cell population, such as adipocytes in adipose tissue. | HPA reports adipocytes in adipose tissue as Not detected (HPA tissue IHC). Check whether the signal follows cell boundaries and persists in a no-primary control; cross-reactivity or endogenous chromogenic activity may explain it (general IHC practice). A result from one cell population does not establish the status of every cell in that tissue. |
| Nearly uniform colour across cells, stroma, and empty areas, with no clear cell-specific pattern. | Diffuse background prevents confident localisation or scoring. Compare a no-primary control, examine wash and blocking steps, and assess the detection reagent (general IHC practice). APLNR's reported staining is cell-specific and described as cytoplasmic in several tissues (HPA tissue IHC); broad background should not be scored as receptor expression. |
| No staining in a selected positive reference, such as heart cardiomyocytes. | HPA reports Medium cardiomyocyte staining, so a blank reference calls for a run-level check (HPA tissue IHC). Confirm that cells of interest are present, then review primary antibody, retrieval, detection, and a working positive control (general IHC practice). HPA's low staining–RNA consistency limits how strongly any single tissue result can be treated as definitive (HPA tissue IHC). |
💡Expected APLNR appearanceCall a result positive when selected cells show discernible membrane-associated or cytoplasmic staining at approximately Medium intensity in HPA-positive populations such as cardiomyocytes or cortical glia; diffuse field-wide or nuclear-only staining is suspect (UniProt P35414 subcellular location; HPA tissue IHC: Medium, cytoplasmic profile).
| Receptor location and trafficking (UniProt P35414 subcellular location) | APLNR resides at the cell membrane and can recycle through endosomes after APELA exposure; apelin-induced internalisation is annotated by similarity (UniProt P35414). This supports evaluating both cell-edge and intracellular signal. The record does not give an IHC-specific ratio of these patterns. |
| Seven transmembrane segments and epitope orientation (UniProt P35414 topology) | Extracellular and cytoplasmic regions alternate across 7 membrane spans (UniProt P35414 topology). The supplied antibody entry gives no epitope, so accessibility or staining distribution cannot be predicted from a particular antibody-binding region (HPA antibodies: CAB025842). |
| Cell-specific reference patterns (HPA tissue IHC) | HPA reports Medium staining in heart cardiomyocytes, caudate neurons, and cortical or hippocampal glia, while adipose-tissue adipocytes and colon glandular cells are Not detected (HPA tissue IHC). Use the named cells when choosing comparisons; do not treat an entire organ as uniformly positive or negative. |
| Validation and source agreement (HPA tissue IHC; HPA antibodies) | The listed IHC antibody, CAB025842, is Approved, while the tissue profile notes low consistency between staining and RNA expression (HPA antibodies; HPA tissue IHC). Interpret a matching pattern as supportive evidence, with cell identity and controls retained in the assessment. |
| Situation | Likely cause | Next action |
|---|---|---|
| Heart reference section is blank. | A run-level staining problem is possible; HPA reports Medium cardiomyocyte staining (HPA tissue IHC). | Verify cardiomyocytes are present, review the primary-antibody and detection steps, and compare a working positive control (general IHC practice). |
| Nuclear signal dominates. | This compartment is unsupported for APLNR (UniProt P35414 subcellular location; HPA tissue IHC). | Check the counterstain and no-primary control, then reassess whether any cell-edge or cytoplasmic signal is distinguishable (general IHC practice). |
| Adipocytes appear strongly positive. | HPA reports adipose-tissue adipocytes as Not detected; nonspecific or endogenous signal is possible (HPA tissue IHC; general IHC practice). | Confirm cell identity and compare a no-primary control before scoring; review blocking and chromogen development if control signal persists (general IHC practice). |
| Brown deposit covers most of the section. | Diffuse background obscures the cell-specific pattern described by HPA (HPA tissue IHC). | Compare no-primary and positive controls; review washing, blocking, antibody concentration, and detection time (general IHC practice). |
| Only cytoplasmic staining is visible. | HPA describes cytoplasmic expression, while UniProt places APLNR at the membrane and in a recycling compartment after ligand exposure (HPA tissue IHC; UniProt P35414). | Assess whether signal is restricted to expected cells and exceeds controls. Do not assign trafficking state from a single paraffin section (general IHC interpretation). |
| Can the same pattern be assumed for IF/ICC? | HPA lists a membrane summary but no ICC-IF image cell lines or main-location entry, and gives no ICC validation for CAB025842 (HPA subcellular; HPA antibodies). | Interpret IF/ICC on its own guide page; use its own cell-level controls and validation. The IHC observations here do not establish an IF/ICC staining pattern (HPA subcellular; HPA antibodies). |
Experiment evidence
IHC & IF images showing APLNR staining
A05042 · IHCImmunohistochemistry validation of APLNR using Anti-Apelin receptor APLNR Antibody (A05042). Immunohistochemical analysis of paraffin-embedd
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000134817-APLNR/tissue/cerebral+cortex#imid_6771296
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000134817-APLNR/tissue/colon#imid_6771222
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000134817-APLNR/tissue/liver#imid_6771223
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000134817-APLNR/tissue/kidney#imid_6771224
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for APLNR IHC & IF
🧪Run cerebral cortex first and look for staining in glial cells (HPA: Medium in cerebral-cortex glial cells). Use cerebellar granular-layer cells as the negative comparison (HPA: Not detected in cerebellar granular-layer cells); on the cortex slide, treat other morphologically distinct cells as internal background references and call them negative only if they lack specific staining.
Positive control tissue: Caudate (Neuronal cells, HPA Medium)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA carries no ICC-IF cell line for APLNR; derive a cell-line control from the positive tissue's cell type (Neuronal cells) and confirm it by RNA or western blot first.
Technical controls: Include a no-primary, secondary-only control; an isotype control matched to the primary antibody’s host species, immunoglobulin class and concentration; and APLNR-knockout tissue, if available, as a biological negative. For cortex sections, quench endogenous peroxidase for chromogenic detection and check unstained sections for brain autofluorescence if using IF (standard IHC/IF practice).
⚠️Feasibility: No target-specific fixation window or fixation effect is reported, and the selected paraffin-section caption does not state a fixative (A05042 tissue-IHC caption). Antigen retrieval dependency is unreported; the supplied evidence does not establish whether frozen sections or IF/ICC would be easier than paraffin IHC. Brain lipofuscin can complicate cortex IF interpretation, so compare fluorescence with an unstained section (standard IF practice).
HPA tissue IHC evidence for APLNR
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 |
|---|---|---|---|---|
| Caudate | Neuronal cells | Medium | Protein (IHC) | HPA → |
| Cerebral cortex | Glial cells | Medium | Protein (IHC) | HPA → |
| Epididymis | Glandular cells | Medium | Protein (IHC) | HPA → |
| Gallbladder | Glandular cells | Medium | Protein (IHC) | HPA → |
| Heart muscle | Cardiomyocytes | Medium | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Adipose tissue | Adipocytes | Not detected | Protein (IHC) | HPA → |
| Appendix | Glandular cells | Not detected | Protein (IHC) | HPA → |
| Breast | Adipocytes | Not detected | Protein (IHC) | HPA → |
| Bronchus | Respiratory epithelial cells | Not detected | Protein (IHC) | HPA → |
| Cerebellum | Cells in granular layer | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced APLNR IHC Tips
Use membrane localisation, cell type and matched controls to evaluate APLNR staining in paraffin sections (UniProt P35414; HPA tissue IHC).
What retrieval conditions should I start with for APLNR in paraffin sections?
Start with citrate buffer at pH 6.0 for heat retrieval at 95–98 °C for 20 minutes (page retrieval rule). Let sections cool in buffer before staining, and keep heating and cooling conditions consistent across slides (standard IHC practice). APLNR has 7 transmembrane segments, so evaluate whether staining outlines cells as well as whether it appears cytoplasmic (UniProt P35414 topology; HPA tissue IHC). If signal remains weak, test EDTA at pH 9 on a matched section as a fallback and compare background (standard IHC practice). Do not treat a stronger signal alone as proof of specificity; check its cell type and compartment (standard IHC practice).
How should I troubleshoot possible fixation effects on APLNR staining?
The A05042 tissue caption reports paraffin-embedded human breast cancer but does not state the fixative, so APLNR-specific fixation sensitivity is unknown (A05042 tissue-IHC caption). Record fixative, fixation duration and processing history for each specimen before comparing staining intensity (standard IHC practice). If weak staining tracks with a processing batch, compare sections from specimens processed under documented, consistent conditions using the same retrieval and detection steps (standard IHC practice). Assess morphology and a control stain alongside APLNR to distinguish tissue damage from a detection problem (standard IHC practice). Avoid assigning a fixation mechanism solely from tissue staining patterns or receptor topology (HPA tissue IHC; UniProt P35414 topology).
Should APLNR staining be membranous, cytoplasmic or both?
Expect cell-surface staining because APLNR is a membrane receptor with 7 transmembrane segments (UniProt P35414 localisation and topology). Cytoplasmic puncta can also fit receptor internalisation into an endosomal recycling compartment after ligand exposure, although staining alone cannot establish that mechanism (UniProt P35414 localisation; standard IHC practice). HPA reports cytoplasmic expression across several tissues and lists membrane localisation in its subcellular summary (HPA tissue IHC; HPA subcellular). Compare staining within intact cells against a no-primary control and inspect the same compartment across matched sections (standard IHC practice). Treat diffuse nuclear staining without a convincing cellular pattern as suspect until independently validated (UniProt P35414 localisation; standard IHC practice).
How does epitope position affect APLNR staining and its interpretation?
APLNR has one annotated 1–380 chain and no annotated isoforms in the supplied record, so do not explain divergent staining by an asserted splice variant (UniProt P35414 record). Its extracellular regions include residues 1–30 and 165–198, while the cytoplasmic tail spans 313–380 (UniProt P35414 topology). Glycosylation sites occur at residues 15 and 175, which may matter when assessing an antibody directed at those regions (UniProt P35414 glycosylation; standard IHC practice). The A05042 caption does not identify the epitope, so confirm antibody documentation before assigning a staining difference to epitope accessibility (A05042 tissue-IHC caption; standard IHC practice). Compare candidate antibodies on matched sections if epitope-dependent recognition remains a concern (standard IHC practice).
How can I assess APLNR by IF alongside a cell-type marker?
For the separate IF/ICC workflow, multiplex APLNR with a validated marker for the expected cell type, such as a glial marker when assessing glial cells (UniProt P35414 tissue specificity; standard IF practice). Include single-stain controls to assess spectral bleed-through and marker overlap (standard IF practice). Choose a far-red fluorophore, such as a 647 nm channel, when shorter-wavelength tissue autofluorescence obscures signal (standard IF practice). Set permeabilisation according to the documented epitope: an intracellular tail requires access through the membrane, while an extracellular epitope can be assessed without that access (UniProt P35414 topology; standard IF practice). Confirm any puncta against no-primary controls before interpreting them as internalised receptor (UniProt P35414 localisation; standard IF practice).
What should I check when APLNR chromogenic staining has high background?
Compare no-primary and matched control sections to locate background from detection reagents or tissue rather than the primary antibody (standard IHC practice). In peroxidase-based detection, include a peroxidase block and inspect whether DAB deposits persist without primary antibody (standard IHC practice). Titrate the primary around the caption’s reported 1:100 dilution on matched sections, keeping retrieval and development consistent (A05042 tissue-IHC caption; standard IHC practice). Adjust blocking and washing if diffuse staining obscures cell boundaries, and review the counterstain for excessive intensity (standard IHC practice). Prioritise reproducible staining in plausible cells and compartments over a uniformly darker section (UniProt P35414 localisation; standard IHC practice).
How should I quantify APLNR staining across tissue sections? ⚠ ANSWER MARKED FOR VERIFICATION
Define the region and cell type before scoring, then record the percentage of positive cells and staining intensity using fixed thresholds (standard IHC practice). An H-score can combine percentages at intensity grades 0–3, yielding a range of 0–300 (standard IHC practice). For spatial questions, count positive cells per mm² of evaluable tissue and report the assessed area (standard IHC practice). Normalise cell counts to the relevant cell population or tissue area, and exclude folds, necrosis and section edges by a rule set before review (standard IHC practice). Keep localisation scores separate because APLNR can appear at the cell surface or in a recycling compartment (UniProt P35414 localisation; standard IHC practice).
How can I distinguish credible APLNR staining from artefact?
Look for reproducible staining in intact cells with membrane or plausible cytoplasmic localisation, supported by appropriate controls (UniProt P35414 localisation; standard IHC practice). HPA reports medium staining in heart cardiomyocytes and cortical glial cells, but its tissue IHC has low consistency with RNA expression (HPA tissue IHC). Judge the cell type within each specimen; a tissue name alone does not establish which cells express APLNR (HPA tissue IHC; standard IHC practice). Discount staining confined to section edges or necrotic regions, and check no-primary sections for endogenous enzyme signal (standard IHC practice). Do not infer ligand-driven internalisation or receptor signalling from a chromogenic pattern alone (UniProt P35414 function and localisation; standard IHC practice).
Boster reagents
Best APLNR / Apelin receptor IHC Antibodies
A05042 has an IHC figure from human paraffin-embedded breast cancer tissue (catalog image caption). The catalog lists IF and reactivity with human, mouse and rat samples (catalog applications and reactivity).
Real IHC data
Anti-Apelin receptor APLNR Antibody
Cat # A05042
A05042 will render with an IHC figure from paraffin-embedded human breast cancer tissue at 1:100 (catalog image caption). IF is listed as an application, and human, mouse and rat are listed as reactive species; no IF figure is supplied (catalog applications, reactivity and image records).
Which to pick: For tissue IHC, choose A05042 for paraffin sections: its own IHC caption documents human breast cancer tissue at 1:100; the fixative is unreported (catalog image caption). For IF, A05042 is the listed option, although the payload supplies no IF image or ICC validation (catalog applications and image records). For mouse or rat work, A05042 lists both species as reactive, while its supplied IHC figure shows human tissue only (catalog reactivity and image caption).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry P35414 (APJ_HUMAN, Apelin receptor).
- Human Protein Atlas. APLNR tissue IHC expression (reliability: Approved).
- Human Protein Atlas. APLNR subcellular location (ICC-IF): Membrane.
- Human Protein Atlas. APLNR antibody validation summary (1 antibodies).
- Unraveling the Complex Molecular Interplay and Vascular Adaptive Changes in Hypertension-Induced Kidney Disease. Biomedicines 2024 — PMC11351430.
- A Morphological and Behavioral Study of Demyelination and Remyelination in the Cuprizone Model: Insights into APLNR and NG2+ Cell Dynamics. International journal of molecular sciences 2024 — PMC11641372.
- Apelin and apelin receptor expression in renal cell carcinoma. British journal of cancer 2019 — PMC6461937.
- Spatiotemporal APLNR Expression Dynamics During Oligodendroglial Remodeling of the Corpus Callosum in the Cuprizone Model. International journal of molecular sciences 2026 — PMC13208026.
- PubMed PMID:8294032 — UniProt-cited evidence.
- PubMed PMID:15489334 — UniProt-cited evidence.
- PubMed PMID:11090199 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for APLNR (Apelin receptor). Expected localisation Cell membrane expected (UniProt); cytoplasmic tissue staining observed (HPA tissue IHC). Antigen retrieval: Citrate pH 6.0 HIER, 95–98 °C, 20 min (rule: cytoplasmic / membrane antigen). Validated IHC antibody: A05042 at 1:100-1:300 (the product's own IHC validation image is shown). Controls (HPA): positive Caudate (Neuronal cells); negative Adipose tissue. IHC workflow; specimen preparation unspecified. Protocol steps: 1. Sample: Paraffin-embedded Human breast cancer tissue; fixative not specified (datasheet A05042); 2. Fixation: Image fixative and duration unreported (datasheet A05042); verify before use.; 3. Sectioning: 4–5 µm sections on charged slides (standard); 4. Deparaffinisation: Xylene, graded ethanol series to water (standard); 5. Antigen retrieval: Heat-induced epitope retrieval in citrate buffer, pH 6.0 , 20 min at 95–98 °C…; 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% normal serum of the secondary host, 30 min , room temperature (standard); 8. Primary antibody: Rabbit anti-APLNR, 1:100-1:300 (datasheet A05042); 9. Primary incubation: Overnight at 4 °C (standard). Watch for: Fixation: Keep fixation consistent across sections. (standard IHC practice; not target-specific); Caveat: Tissue staining has low consistency with RNA expression (HPA tissue IHC); Isoform / epitope: No isoforms annotated; extracellular versus cytoplasmic epitope matters (UniProt); Regulation: Ligand exposure shifts APLNR from the surface to endosomes (UniProt). Evidence: UniProt P35414, HPA tissue IHC · Approved, HPA ICC-IF · Membrane, Datasheet A05042, PMC11351430, PMC11641372. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/APLNR/immunohistochemistry-ihc-guide.