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GRM2 / Metabotropic glutamate receptor 2 · IHC design guide
Design Immunohistochemistry for GRM2
Plan GRM2 chromogenic IHC in paraffin sections using the catalog antibody’s IHC-P conditions (datasheet A06123-1). Compare cerebral cortex neuropil staining with a non-detected tissue and interpret the cytoplasmic tissue pattern alongside GRM2’s synaptic membrane location (HPA tissue IHC; UniProt).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
GRM2 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 | CNS cytoplasmic staining; synaptic membrane expected (HPA tissue IHC; UniProt) | |
| Staining pattern | Cytoplasmic CNS staining, including cerebral cortex neuropil (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet A06123-1) | |
| Positive control | Cerebral cortex | |
| 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 | Antibody staining has low concordance with RNA expression (HPA tissue IHC) | |
| Regulation | No specific expression regulator reported (UniProt) | |
| Isoform / epitope | 0 annotated isoforms; epitope side matters across 7 membrane spans (UniProt) |
Section 1
Recommended GRM2 IHC & IF Protocols
The catalog antibody’s IHC-P protocol (datasheet A06123-1) is followed by one published paraffin-section GRM2 protocol (PMC9536148).
| Sample | Paraffin-embedded human glioma tissue; fixative not specified (datasheet A06123-1) |
| Fixation | Image fixative and duration unreported (datasheet A06123-1); verify before use. |
| Sectioning | 4–5 µm sections on charged slides (standard) |
| Deparaffinisation | Xylene, graded ethanol series to water (standard) |
| Antigen retrieval | Heat retrieval: EDTA pH 8.0 (datasheet A06123-1); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet A06123-1) |
| Primary antibody | Rabbit anti-GRM2, 0.5-1μg/ml recommended; image 2 μg/ml (datasheet A06123-1) |
| Primary incubation | Overnight at 4 °C (datasheet A06123-1) |
| Detection | HRP-conjugated secondary, DAB chromogen (datasheet A06123-1) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | GRM2-positive staining in neuropil of cerebral cortex (HPA tissue IHC: Medium). HPA tissue profile: Cytoplasmic expression in CNS. No signal in the no-primary control. |
💡Decision noteStart with heat-mediated EDTA pH 8.0 retrieval (datasheet A06123-1); the published rat carotid body protocol used citrate pH 6.0 (PMC9536148).
Section 2
What Is the Expected GRM2 Staining Pattern?
GRM2 is a seven-pass membrane receptor at synapses and dendrites (UniProt Q14416 topology/localisation). In IHC, expect staining in cerebral cortex neuropil, with weaker staining reported in hippocampal neurons and cerebellar granular-layer cells (HPA tissue IHC: Medium/Low). HPA also describes cytoplasmic expression in the CNS; its tissue IHC reliability is Approved, with low consistency between antibody staining and RNA expression (HPA tissue IHC).
| Cerebral cortex neuropil has a moderate chromogenic signal. | This matches the strongest supplied tissue observation (HPA tissue IHC: Medium in cerebral cortex neuropil). Read a neuropil-rich pattern alongside GRM2's synaptic and dendritic localisation; IHC may not resolve receptor-bearing membranes individually (UniProt Q14416 localisation; general IHC practice). |
| Hippocampal neuronal cells or cerebellar granular-layer cells show weak staining. | Low staining is reported in these cells (HPA tissue IHC: Low). Compare intensity within the same staining run; a weak result here is less decisive than a cerebral cortex neuropil result (HPA tissue IHC: Medium; general IHC practice). |
| Signal is confined to nuclei, with no corresponding CNS neuropil pattern. | An exclusively nuclear pattern is unsupported by the supplied localisation evidence (UniProt Q14416 localisation; HPA tissue IHC). Treat it as suspect and inspect controls before assigning it to GRM2 (general IHC practice). HPA's broad ‘cytoplasmic expression in CNS’ description alone does not make all non-membrane-looking signal erroneous (HPA tissue IHC). |
| Prominent staining appears in adrenal glandular cells or adipocytes. | Those sampled cell types were not detected by HPA tissue IHC (HPA tissue IHC: adrenal glandular cells and adipocytes, Not detected). Investigate cross-reactivity or endogenous detection activity, especially if the expected cortex neuropil pattern is absent (general IHC practice; HPA tissue IHC: cerebral cortex neuropil, Medium). |
| The whole section has diffuse colour, or cortex neuropil has no signal. | Diffuse colour obscures the expected cell pattern and suggests background; absent cortex signal needs a run-level check because cortex neuropil was Medium in HPA (general IHC practice; HPA tissue IHC). Neither finding alone establishes that the tissue lacks GRM2, particularly given HPA's low staining–RNA consistency (HPA tissue IHC). |
💡Expected GRM2 appearanceCall the result positive when cerebral cortex neuropil shows a discernible Medium signal (HPA tissue IHC), consistent with synaptic/dendritic membrane localisation (UniProt Q14416); uniform nuclear or widespread negative-cell staining is suspect (UniProt Q14416 localisation; HPA tissue IHC: Not detected in sampled negative cells).
| Tissue and cell selection | Cerebral cortex neuropil is the clearest supplied positive comparison; hippocampal neurons and cerebellar granular-layer cells have Low staining (HPA tissue IHC). Sampled adipocytes and adrenal glandular cells were Not detected, providing pattern comparisons rather than proof that every cell of those tissues is negative (HPA tissue IHC). |
| Membrane topology and antibody epitope | GRM2 has 7 transmembrane segments, a large extracellular region at residues 19–567, and a cytoplasmic C terminus at 820–872 (UniProt Q14416 topology). Epitope location can affect how an antibody reads a section, but the supplied record gives no catalog-antibody epitope; do not assume which face it recognises (UniProt Q14416 topology; supplied evidence). |
| Maturation and glycosylation | The annotated signal peptide spans residues 1–18; the receptor chain begins at residue 19, with 5 glycosylation sites annotated (UniProt Q14416 processing/glycosylation). These features describe the protein; the supplied sources do not establish a retrieval setting, epitope loss, or staining change caused by them. |
| Antibody validation and interpretation limit | Two listed antibodies have different HPA IHC statuses: HPA027868 is Supported and HPA065166 is Approved (HPA antibodies). HPA tissue IHC is Approved but reports low consistency with RNA expression; assess the observed cell pattern and controls before making a strong specificity claim (HPA tissue IHC; general IHC practice). |
| Antigen retrieval choice | Retrieval is a general variable in paraffin-section IHC and should follow the chosen IHC-validated antibody's instructions, with a known-positive section alongside it (general IHC practice). UniProt and HPA provide no GRM2-specific retrieval condition or fixation-sensitivity result in the supplied evidence. |
| Situation | Likely cause | Next action |
|---|---|---|
| No signal in cerebral cortex neuropil. | The expected Medium HPA pattern is missing; staining-run failure, unsuitable detection, or a specimen issue are possibilities (HPA tissue IHC; general IHC practice). | Check the IHC-validated antibody's stated paraffin-section conditions, a concurrent known-positive section, and detection controls; then reassess the neuropil pattern (general IHC practice). |
| Only faint hippocampal or cerebellar staining is visible. | Low staining is reported for hippocampal neuronal cells and cerebellar granular-layer cells (HPA tissue IHC: Low). | Include cerebral cortex neuropil as the stronger supplied comparison, then judge whether the weak signal follows the reported cells (HPA tissue IHC: cortex Medium; general IHC practice). |
| Strong nuclear staining dominates the section. | Exclusive nuclear localisation lacks support in UniProt's membrane/synapse/dendrite annotation and HPA's CNS IHC description (UniProt Q14416 localisation; HPA tissue IHC). | Review a no-primary detection control and the tissue pattern; avoid scoring nuclear colour as GRM2 without independent support (general IHC practice). |
| Colour appears in negative-comparison cell types. | Adrenal glandular cells and adipocytes were Not detected in the supplied HPA samples; cross-reactivity or endogenous chromogenic activity may contribute (HPA tissue IHC; general IHC practice). | Compare a no-primary control and the positive cortex section; check that the detection system's endogenous-activity blocking step was performed (general IHC practice). |
| Diffuse background hides neuropil detail. | Nonspecific antibody binding, incomplete blocking, or excess chromogenic development can reduce contrast (general IHC practice). | Inspect no-primary and tissue controls; review blocking, antibody dilution, washes, and development against the chosen antibody's IHC instructions (general IHC practice). |
| Can ICC-IF establish the expected IHC-P pattern? | HPA lists a Membrane subcellular summary but no ICC-IF image-bearing cell lines here; neither listed HPA antibody has an ICC status in the supplied payload (HPA subcellular; HPA antibodies). | Use this page's cortex neuropil IHC result as the paraffin-section reference (HPA tissue IHC: Medium); consult the separate IF/ICC guide for that application. Do not treat the HPA subcellular summary as an ICC-IF validation result (HPA subcellular). |
Experiment evidence
IHC & IF images showing GRM2 staining
A06123-1 · IHCIHC analysis of GRM2 using anti-GRM2 antibody (A06123-1). GRM2 was detected in a paraffin-embedded section of human glioma tissue. Heat medi
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000164082-GRM2/tissue/cerebral+cortex#imid_17762935
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000164082-GRM2/tissue/colon#imid_17762869
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000164082-GRM2/tissue/liver#imid_17762862
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000164082-GRM2/tissue/kidney#imid_17762871
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for GRM2 IHC & IF
🧪Run cerebral cortex first and look for staining in the neuropil (HPA: Medium in cerebral cortex neuropil). Use adipose tissue as a negative tissue, with adipocytes expected to remain at background (HPA: Not detected in adipocytes); on the cortex slide, nuclei should remain unstained relative to neuropil (UniProt Q14416: membrane and synaptic localisation).
Positive control tissue: Cerebral cortex (Neuropil, 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 GRM2; derive a cell-line control from the positive tissue's cell type (Neuropil) and confirm it by RNA or western blot first.
Technical controls: Include a no-primary, secondary-only slide, a matched rabbit IgG isotype control, and GRM2 knockout tissue if available (selected IHC caption: rabbit primary antibody; standard IHC controls). For chromogenic cortex sections, quench endogenous peroxidase and inspect tissue pigment before scoring DAB signal (selected IHC caption: HRP/DAB detection; standard IHC practice).
⚠️Feasibility: No target-specific fixation window or fixation effect is reported in the supplied evidence, and the selected A06123-1 tissue-IHC caption does not state a fixative. That paraffin-section example uses heat retrieval in EDTA at pH 8.0, but it does not establish how retrieval-dependent GRM2 staining is (selected IHC caption). The evidence does not establish that frozen sections or IF are easier; in cortex, distinguish neuropil staining from tissue pigment and background (HPA: Medium in cerebral cortex neuropil; standard IHC practice).
HPA tissue IHC evidence for GRM2
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 |
|---|---|---|---|---|
| Cerebral cortex | Neuropil | Medium | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Adipose tissue | Adipocytes | Not detected | Protein (IHC) | HPA → |
| 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 → |
| Breast | Adipocytes | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced GRM2 IHC Tips
Troubleshoot GRM2 staining in paraffin sections by checking retrieval, localisation and controls before interpreting chromogenic signal.
What retrieval should I start with for GRM2 in paraffin sections?
Use heat-mediated retrieval in EDTA at pH 8.0 for paraffin sections (datasheet A06123-1). The selected tissue image used this condition before incubation with 2 μg/ml primary antibody overnight at 4°C (caption A06123-1). If staining is weak, first check that sections were fully deparaffinised and that the retrieval bath reached a consistent temperature across slides (standard IHC practice). Compare any later change in retrieval duration with the EDTA-treated reference on the same run, using tissue morphology and background as well as signal to judge the result (standard IHC practice).
How should I assess whether fixation is affecting GRM2 staining?
The selected image describes a paraffin section but does not state its fixative, so GRM2-specific fixation sensitivity is unknown (caption A06123-1). Record the fixative, fixation duration and section processing for each specimen, and compare specimens only when those conditions are sufficiently matched (standard IHC practice). If signal varies, stain a reference section in the same run using EDTA at pH 8.0 and the documented 2 μg/ml primary concentration (datasheet A06123-1; caption A06123-1). Assess morphology and staining together, and treat a difference between fixation groups as an observation requiring controlled comparison rather than proof of a GRM2-specific fixation effect (standard IHC practice).
Which staining pattern is plausible for GRM2 in brain sections?
Look for signal associated with neuronal processes and membranes: GRM2 is annotated at the cell membrane, synapse and dendrite (UniProt Q14416 localisation). In tissue IHC, the reported positive pattern is medium neuropil staining in cerebral cortex, with low staining reported in hippocampal neuronal cells and cerebellar granular-layer cells (HPA tissue IHC). HPA also describes cytoplasmic expression in CNS, so a diffuse chromogenic appearance can coexist with limited resolution of fine processes (HPA tissue IHC; standard IHC practice). Compare the pattern with local anatomy and matched controls before assigning a stained profile to a particular cell or membrane compartment (standard IHC practice).
How can epitope position complicate GRM2 IHC interpretation?
Check the antibody’s documented immunogen before interpreting accessibility, because the selected caption does not identify its epitope (caption A06123-1). GRM2 has an extracellular region at residues 19–567, 7 transmembrane segments and a cytoplasmic tail at 820–872 (UniProt Q14416 topology). Its annotated glycosylation sites at 203, 286, 338, 402 and 547 lie in that extracellular region, but their effect on this antibody’s staining is untested here (UniProt Q14416 glycosylation; caption A06123-1). UniProt lists 0 annotated isoforms; do not use that annotation to infer which epitope the antibody recognises or to explain a discordant staining pattern (UniProt Q14416 isoforms; standard IHC practice).
How should I evaluate GRM2 by multiplex IF after IHC?
Treat IF as a separate assay: the supplied image documents chromogenic staining in a paraffin section, with no IF validation or fixative reported (caption A06123-1). Pair GRM2 with a validated neuronal marker to assess whether signal follows the expected neuronal processes, while keeping the marker’s specificity under review (UniProt Q14416 localisation; standard IF practice). Choose spectrally separated fluorophores after checking tissue autofluorescence in unstained sections, and include single-label controls when setting channels (standard IF practice). Once the antibody epitope is known, optimise permeabilisation for its extracellular or cytoplasmic side and assess whether that treatment changes morphology or background (UniProt Q14416 topology; standard IF practice).
What should I check when GRM2 DAB staining is widespread?
Start with a no-primary control to identify signal from the detection system, and assess endogenous peroxidase activity before DAB development (standard chromogenic IHC practice). The selected image used 10% goat serum blocking, 2 μg/ml primary antibody overnight at 4°C, and peroxidase-conjugated secondary antibody for 30 minutes at 37°C (caption A06123-1). Keep these documented conditions as a reference while checking wash consistency, section edges and any precipitated chromogen (caption A06123-1; standard IHC practice). Compare the signal with cerebral cortex neuropil and an HPA-reported negative tissue, recognising that the HPA staining has low consistency with RNA expression (HPA tissue IHC).
How should I quantify GRM2 staining across paraffin sections? ⚠ ANSWER MARKED FOR VERIFICATION
Define anatomical regions before scoring, because HPA reports medium cerebral cortex neuropil staining and low hippocampal neuronal-cell staining (HPA tissue IHC). For identifiable cells, report the percentage positive and an intensity-weighted H-score; for neuropil, measure DAB-positive area or optical density per mm² of analysable region (standard quantitative IHC practice). Apply the same threshold, counterstain settings and exclusion rules to all sections, excluding folds, edges and damaged or necrotic areas (standard quantitative IHC practice). Normalise neuropil measurements to analysable tissue area and cell scores to the number of eligible cells, then report regions separately rather than pooling unlike compartments (standard quantitative IHC practice).
When is a GRM2-positive result convincing rather than artefactual?
A convincing result follows plausible neuronal processes or membranes and reproduces in comparable sections, consistent with GRM2’s synaptic, dendritic and cell-membrane annotations (UniProt Q14416 localisation; standard IHC practice). Cerebral cortex neuropil provides a reported positive pattern, but HPA rates its tissue staining as Approved while noting low consistency with RNA expression (HPA tissue IHC). Treat isolated nuclear signal, strong staining confined to section edges or necrosis, and signal persisting in a no-primary control as reasons to investigate artefact (UniProt Q14416 localisation; standard IHC practice). Check endogenous peroxidase and DAB background before attributing unexpected staining to GRM2, and avoid declaring a new cell type positive from chromogen alone (standard chromogenic IHC practice).
Boster reagents
Best GRM2 / Metabotropic glutamate receptor 2 IHC Antibodies
Anti-GRM2 options list human, mouse and rat reactivity (catalog reactivity: A06123-1, M06123); the supplied IHC image shows a human glioma paraffin section (A06123-1 image caption).
Real IHC data
Anti-Metabotropic glutamate receptor 2/GRM2 Antibody ®
Cat # A06123-1
A06123-1 is listed for IHC (catalog applications: A06123-1), with an IHC image from human glioma paraffin tissue (A06123-1 image caption). M06123 is listed for IHC and ICC/IF (catalog applications: M06123) and human, mouse and rat reactivity (catalog reactivity: M06123); no IHC or IF image is supplied (catalog image alts: M06123).
Which to pick: For tissue IHC, choose A06123-1 because its image documents staining in a human glioma paraffin section; the fixative is unreported (A06123-1 image caption). For IF/ICC, choose the rabbit monoclonal M06123 based on its listed applications, while recognizing that no IF image is supplied (catalog host/clone, applications and image alts: M06123). Both list human, mouse and rat reactivity for cross-species work (catalog reactivity: A06123-1, M06123), but the supplied tissue image documents human staining only (A06123-1 image caption).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry Q14416 (GRM2_HUMAN, Metabotropic glutamate receptor 2).
- Human Protein Atlas. GRM2 tissue IHC expression (reliability: Approved).
- Human Protein Atlas. GRM2 subcellular location (ICC-IF): Membrane.
- Human Protein Atlas. GRM2 antibody validation summary (2 antibodies).
- Group II metabotropic glutamate receptor expressing neurons in anterior cingulate cortex become sensitized after inflammatory and neuropathic pain. Molecular pain 2020 — PMC7227149.
- Expression of group II and III mGluRs in the carotid body and its role in the carotid chemoreceptor response to acute hypoxia. Frontiers in physiology 2022 — PMC9536148.
- PubMed PMID:7620613 — UniProt-cited evidence.
- PubMed PMID:15489334 — UniProt-cited evidence.
- PubMed PMID:18297054 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for GRM2 (Metabotropic glutamate receptor 2). Expected localisation CNS cytoplasmic staining; synaptic membrane expected (HPA tissue IHC; UniProt). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet A06123-1). Validated IHC antibody: A06123-1 at 0.5-1μg/ml recommended; image 2 μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Cerebral cortex (Neuropil); negative Adipose tissue. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human glioma tissue; fixative not specified (datasheet A06123-1); 2. Fixation: Image fixative and duration unreported (datasheet A06123-1); 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 retrieval: EDTA pH 8.0 (datasheet A06123-1); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet A06123-1); 8. Primary antibody: Rabbit anti-GRM2, 0.5-1μg/ml recommended; image 2 μg/ml (datasheet A06123-1); 9. Primary incubation: Overnight at 4 °C (datasheet A06123-1). Watch for: Fixation: Keep fixation consistent across sections (standard IHC practice; not target-specific); Caveat: Antibody staining has low concordance with RNA expression (HPA tissue IHC); Isoform / epitope: 0 annotated isoforms; epitope side matters across 7 membrane spans (UniProt); Regulation: No specific expression regulator reported (UniProt). Evidence: UniProt Q14416, HPA tissue IHC · Approved, HPA ICC-IF · Membrane, Datasheet A06123-1, PMC9536148. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/GRM2/immunohistochemistry-ihc-guide.