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CHRM1 / Muscarinic acetylcholine receptor M1 · IHC design guide
Design Immunohistochemistry for CHRM1
Plan chromogenic CHRM1 IHC on paraffin sections using the catalog antibody’s documented human cerebellum example (datasheet A04081). Assess neuronal cytoplasmic staining against the tissue profile (HPA tissue IHC), while treating membrane localisation as a molecular expectation (UniProt).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
CHRM1 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 | Neuronal cytoplasm observed; membrane expected (HPA tissue IHC; UniProt) | |
| Staining pattern | Cytoplasmic staining in pyramidal neurons and Purkinje cells (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet A04081) | |
| Positive control | Cerebellum+2 more · see all | |
| Negative control | Adipose tissue+4 more · see all |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Keep paraffin-section fixation consistent across samples (standard IHC practice; not target-specific) | |
| Caveat | Staining has medium consistency with RNA expression (HPA tissue IHC) | |
| Regulation | No expression regulator is annotated (UniProt) | |
| Isoform / epitope | 2 isoforms; extracellular versus cytoplasmic epitope coverage is unknown (UniProt) |
Section 1
Recommended CHRM1 IHC & IF Protocols
The catalog antibody’s IHC-P protocol (datasheet A04081) is accompanied by published CHRM1 protocols for human prostate samples (PMC6219293), mouse tumors (PMC9203210), and rat hippocampus (PMC7811316).
| Sample | Paraffin-embedded mouse brain tissue; fixative not specified (datasheet A04081) |
| Fixation | Image fixative and duration unreported (datasheet A04081); 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 A04081); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet A04081) |
| Primary antibody | Rabbit anti-CHRM1, 0.5-1μg/ml (datasheet A04081) |
| Primary incubation | Overnight at 4 °C (datasheet A04081) |
| Detection | Streptavidin-biotin complex (SABC), DAB chromogen (datasheet A04081) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | CHRM1-positive staining in molecular layer cells - cytoplasm/membrane of cerebellum (HPA tissue IHC: High). HPA tissue profile: Cytoplasmic expression in pyramidal neurons and Purkinje cells. No signal in the no-primary control. |
💡Decision noteStart with heat-mediated EDTA at pH 8.0 for the catalog antibody (datasheet A04081). For rat hippocampal sections, citrate at pH 6 is a published alternative (PMC7811316).
Section 2
What Is the Expected CHRM1 Staining Pattern?
CHRM1 is a 7-transmembrane receptor at the cell membrane, including postsynaptic membranes (UniProt P11229 topology; subcellular location). In IHC, expect neuronal staining: cytoplasmic staining in pyramidal neurons and Purkinje cells, and cytoplasmic/membrane staining in cerebellar molecular-layer cells (HPA: tissue IHC). HPA rates its tissue IHC profile Enhanced, with medium consistency between staining and RNA data and support from external characterization (HPA: reliability).
| Distinct neuronal staining in cerebellum, with cytoplasmic/membrane signal in molecular-layer cells. | This matches the strongest listed tissue result: High staining in cerebellar molecular-layer cells (HPA: tissue IHC). Cytoplasmic staining in Purkinje cells also fits HPA's profile. The membrane component agrees with receptor location (UniProt P11229: subcellular location). |
| Neuronal staining in cerebral cortex or hippocampus is visible but less prominent than in the cerebellar example. | HPA reports Medium staining in neuronal cells in both regions and High staining in cerebellar molecular-layer cells (HPA: tissue IHC). Compare the identified cell populations; a whole-section intensity judgment can obscure which cells carry the signal. |
| Staining is predominantly nuclear, with no convincing neuronal cytoplasmic or membrane pattern. | An isolated nuclear pattern does not match HPA's neuronal cytoplasmic profile or UniProt's membrane assignment (HPA: tissue IHC; UniProt P11229: subcellular location). Treat it as a possible staining artefact and assess counterstain overlap and detection controls before assigning CHRM1 positivity (general IHC practice). |
| Strong staining appears mainly in adipocytes, or in another cell population HPA lists as undetected. | HPA lists adipocytes in adipose tissue as Not detected (HPA: tissue IHC). The unexpected signal raises the possibility of cross-reactivity or endogenous detection activity; neither can be distinguished by appearance alone. Check cell identity and detection controls (general IHC practice). |
| Diffuse colour covers multiple compartments or the full section, including regions without identifiable positive cells. | This cannot establish the cell-restricted pattern HPA describes (HPA: tissue IHC). Background from detection reagents, insufficient blocking or nonspecific antibody binding is possible (general IHC practice). Judge staining against a matched control section and the tissue's morphology. |
💡Expected CHRM1 appearanceCall positive a defined neuronal cytoplasmic/membrane pattern, strongest in HPA's cerebellar molecular-layer example (High) and present at Medium levels in cortical or hippocampal neurons; isolated nuclear staining or broad colour without identifiable positive cells is suspect (HPA: tissue IHC; UniProt P11229: subcellular location).
| Compartment and epitope position | CHRM1 spans the membrane 7 times and has extracellular and cytoplasmic regions (UniProt P11229 topology). Epitope position for the listed IHC antibody is unspecified (HPA: antibody record); topology alone cannot predict which slide preparation or retrieval condition will expose it. |
| Tissue and cell selection | HPA reports High cerebellar molecular-layer staining, Medium cortical and hippocampal neuronal staining, and undetected adipose adipocytes (HPA: tissue IHC). Select and score the named cells; the tissue name alone does not make every cell a positive or negative control. |
| Strength of the IHC evidence | HPA assigns tissue staining Enhanced reliability, while describing medium staining/RNA consistency and external characterization support (HPA: reliability). Its listed antibody HPA014101 has IHC Enhanced status (HPA: antibody record). These ratings support pattern interpretation; they do not validate every new staining run. |
| IF/ICC applicability? | HPA summarizes the subcellular location as membrane but supplies no ICC-IF image cell lines or ICC validation for its listed antibody (HPA: subcellular and antibody records). Use that location as context only; the supplied evidence does not establish an IF/ICC staining pattern or working conditions. |
| Situation | Likely cause | Next action |
|---|---|---|
| No staining in a cerebellar section expected to contain the relevant cells. | The High HPA result refers specifically to molecular-layer cells (HPA: tissue IHC); absence of those cells in the examined area, or an unsuccessful staining run, can explain the observation. | Confirm the cell population on the counterstained section, then check a positive-control run and the antibody, retrieval and detection steps (general IHC practice). Target-specific fixation sensitivity is unreported in the supplied sources. |
| Cortex or hippocampus seems negative when compared with a strongly stained cerebellar control. | HPA rates neuronal staining in those regions Medium, versus High in cerebellar molecular-layer cells (HPA: tissue IHC). A stronger control does not set the expected intensity for every region. | Inspect neurons directly at the same scoring threshold and review control performance before calling the section negative (general IHC practice). Record the region and cell type with the score. |
| Colour is spread across the section, obscuring neuronal boundaries. | Diffuse signal does not resemble HPA's cell-specific profile (HPA: tissue IHC). Nonspecific binding, incomplete blocking or detection background are possible explanations (general IHC practice). | Review a section processed without primary antibody and the run's blocking and detection controls; optimize the workflow if background persists (general IHC practice). Do not score diffuse colour as neuronal CHRM1. |
| Staining is strongest in nuclei while neuronal cytoplasm and membranes are weak. | The dominant nuclear distribution conflicts with the reported cytoplasmic neuronal profile and membrane location (HPA: tissue IHC; UniProt P11229: subcellular location). | Check whether counterstain is being mistaken for chromogen, inspect a matched control section, and reassess antibody-specific signal before reporting localisation (general IHC practice). |
| Adipocytes show a strong chromogenic signal. | Adipocytes in adipose tissue are listed as Not detected (HPA: tissue IHC). Cross-reactivity or endogenous detection activity is plausible, but this image alone cannot identify the cause. | Confirm the cell type, run a no-primary control, and check endogenous-activity blocking appropriate to the detection chemistry (general IHC practice). Compare with a neuronal positive control before interpreting the signal. |
| The same apparent signal occurs in both positive tissue and a no-primary control. | Signal without primary antibody implicates the detection workflow rather than antibody binding (general IHC practice); it cannot confirm HPA's neuronal pattern (HPA: tissue IHC). | Check detection reagents and appropriate endogenous-activity blocking, then repeat with a clean control (general IHC practice). Score CHRM1 only after cell-specific signal exceeds that control. |
Experiment evidence
IHC & IF images showing CHRM1 staining
A04081 · IHCIHC analysis of CHRM1 using anti-CHRM1 antibody (A04081). CHRM1 was detected in paraffin-embedded section of mouse brain tissue. Heat mediat
A04081 · IHCIHC analysis of CHRM1 using anti-CHRM1 antibody (A04081). CHRM1 was detected in paraffin-embedded section of rat brain tissue. Heat mediated
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000168539-CHRM1/tissue/cerebral+cortex#imid_18773324
HPA · CerebellumHuman Protein Atlas IHC, Cerebellum. Source: https://www.proteinatlas.org/ENSG00000168539-CHRM1/tissue/cerebellum#imid_18773327
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000168539-CHRM1/tissue/colon#imid_18773250
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000168539-CHRM1/tissue/liver#imid_18773259
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for CHRM1 IHC & IF
🧪Run cerebellum first and look for staining in molecular layer cells (HPA: High, cytoplasm/membrane). Use adipose tissue as the negative tissue, checking that adipocytes remain at background (HPA: Not detected in adipocytes); on the cerebellum slide, assess cells outside the reported molecular layer pattern as an internal background reference (HPA: molecular layer cells are the reported positive population).
Positive control tissue: Cerebellum (Molecular layer cells - cytoplasm/membrane, HPA High)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA carries no ICC-IF cell line for CHRM1; derive a cell-line control from the positive tissue's cell type (Molecular layer cells - cytoplasm/membrane) and confirm it by RNA or western blot first.
Technical controls: Include a no-primary (secondary-only) control, a rabbit IgG isotype control matched to the primary antibody’s class and clonality where known, and CHRM1 knockout tissue as a biological negative (caption: rabbit anti-CHRM1; standard IHC practice). Quench endogenous peroxidase and check for endogenous biotin in cerebellum because the reported detection uses a biotinylated secondary and streptavidin–biotin complex (caption: mouse brain, SABC/DAB; standard IHC practice).
⚠️Feasibility: A CHRM1-specific fixation window or fixation effect is unreported, and the selected SKU’s paraffin-section caption does not state a fixative (caption: fixative not stated). The reported mouse brain IHC used heat retrieval in EDTA at pH 8.0, but the evidence does not establish that retrieval is required for every specimen (caption: mouse brain IHC). Whether frozen sections or IF are easier is unreported; with the reported biotin-based chromogenic method, assess brain sections for endogenous biotin background (caption: SABC/DAB; standard IHC practice).
HPA tissue IHC evidence for CHRM1
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Enhanced — Medium consistency between antibody staining and RNA expression data. External characterization data supports antibody staining.). 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 |
|---|---|---|---|---|
| Cerebellum | Molecular layer cells - cytoplasm/membrane | High | Protein (IHC) | HPA → |
| Cerebral cortex | Neuronal cells | Medium | Protein (IHC) | HPA → |
| Hippocampus | Neuronal cells | 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 | Endocrine 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 CHRM1 IHC Tips
Use the catalog antibody’s paraffin-section IHC conditions as the starting point, then assess staining against CHRM1’s reported cellular distribution and appropriate controls.
Which retrieval condition should I start with for CHRM1 in paraffin sections?
Start with heat-mediated retrieval in EDTA at pH 8.0 for paraffin sections stained with A04081 (datasheet A04081). Keep heating and cooling conditions consistent across the study, and include a known staining control in each run (standard IHC practice). CHRM1 has 7 transmembrane segments, but the antibody’s recognized epitope is not specified here (UniProt P11229 topology; datasheet A04081). If staining remains weak, compare a second retrieval condition on matched sections as a troubleshooting fallback, while retaining EDTA at pH 8.0 as the reference (standard IHC practice). Judge improvement by cellular pattern and background together, rather than DAB intensity alone (standard IHC practice).
How should I troubleshoot variable CHRM1 staining across differently processed blocks?
The A04081 tissue caption identifies paraffin sections but does not state the fixative, so target-specific fixation sensitivity is unknown (datasheet A04081). Record each block’s fixation and processing history before attributing a weak result to CHRM1 abundance (standard IHC practice). Compare blocks using the same EDTA retrieval at pH 8.0, antibody concentration of 1 µg/ml, and overnight incubation at 4°C used in the caption (datasheet A04081). Include similarly processed control sections and review morphology, because uneven preservation can complicate comparisons of staining intensity (standard IHC practice). Report processing differences alongside the scores instead of treating unmatched blocks as directly equivalent (standard IHC practice).
Should CHRM1 staining be membranous, cytoplasmic, or both in neuronal tissue?
CHRM1 is annotated at the cell membrane and postsynaptic cell membrane, consistent with its 7-segment receptor topology (UniProt P11229). The HPA tissue profile also reports cytoplasmic staining in pyramidal neurons and Purkinje cells, with cytoplasm or membrane staining in cerebellar molecular-layer cells (HPA tissue IHC). In chromogenic sections, assess whether DAB follows plausible neuronal cell bodies and processes rather than demanding a crisp membrane outline in every cell (HPA tissue IHC; standard IHC practice). Compare the pattern with adjacent morphology and a control section processed in the same run (standard IHC practice). Diffuse staining throughout unrelated cell populations deserves a specificity check before it is scored as receptor expression (standard IHC practice).
Can this antibody distinguish CHRM1 isoforms or extracellular from intracellular epitopes?
CHRM1 has 2 annotated isoforms, but the supplied evidence does not identify which isoform or epitope A04081 recognizes (UniProt P11229; datasheet A04081). Its topology places residues 1–22 extracellularly and residues 210–366 cytoplasmically, among other loops (UniProt P11229 topology). Glycosylation is annotated at residues 2 and 12, but these sites alone do not establish an effect on this antibody’s staining (UniProt P11229; datasheet A04081). Interpret DAB as CHRM1 immunoreactivity without assigning it to a particular isoform or membrane-facing epitope (standard IHC practice). For an isoform-specific claim, obtain epitope and isoform coverage information or independent validation first (standard IHC practice).
How can I follow up the chromogenic CHRM1 pattern with multiplex IF?
Treat multiplex IF as a separate optimization: the supplied A04081 image documents paraffin-section chromogenic IHC, with no IF result provided (datasheet A04081). Pair CHRM1 with a neuronal marker selected for the expected cells, since HPA reports staining in pyramidal neurons and Purkinje cells (HPA tissue IHC). Check an unstained section for autofluorescence, then choose spectrally separated fluorophores, favoring a far-red channel when shorter wavelengths are noisy (standard IF practice). If the antibody recognizes a cytoplasmic loop, evaluate permeabilisation; if it recognizes an extracellular epitope, compare conditions that preserve surface staining (UniProt P11229 topology; standard IF practice). Confirm the IF pattern against the chromogenic result and single-label controls before interpreting colocalisation (standard IF practice).
What should I check when CHRM1 DAB staining is widespread or granular?
The pictured workflow uses 10% goat serum blocking, a biotinylated secondary, a streptavidin–biotin complex, and DAB (datasheet A04081). Check a no-primary control for signal from detection reagents, including endogenous biotin, before calling widespread brown staining CHRM1-positive (standard IHC practice). Include a peroxidase block and inspect its effectiveness, because DAB development can reveal endogenous enzyme activity independently of the target (standard IHC practice). Titrate the primary around the documented 1 µg/ml condition and keep development time consistent across sections (datasheet A04081; standard IHC practice). Compare granular deposits with tissue morphology and controls; isolated precipitate or staining concentrated at section edges should not enter the CHRM1 score (standard IHC practice).
How should I score CHRM1 staining when cell types and tissue areas differ? ⚠ ANSWER MARKED FOR VERIFICATION
Define neuronal regions and cell populations before scoring, because HPA reports CHRM1 staining in selected neuronal populations rather than uniformly across tissue (HPA tissue IHC). For cellular staining, record the percentage of positive cells and intensity, or use an H-score from 0–300 with intensity grades 0–3 (standard IHC practice). Normalize positive-cell counts to the number of eligible cells in each region; normalize stained area or cell density to the measured region in mm² (standard IHC practice). Apply one threshold and the same DAB exposure and imaging settings across comparison groups (standard IHC practice). Report membranous and cytoplasmic patterns separately when both are reliably distinguishable (UniProt P11229; HPA tissue IHC).
How can I separate genuine CHRM1 staining from section or detection artefacts?
Look for staining in plausible neuronal populations and compare it with CHRM1’s membrane and postsynaptic annotations and HPA’s neuronal tissue pattern (UniProt P11229; HPA tissue IHC). HPA reports high staining in cerebellar molecular-layer cells, medium staining in cortical and hippocampal neurons, and no detection in adipocytes from adipose tissue (HPA tissue IHC). Flag staining confined to cut edges, necrotic areas, or unrelated cells for review against morphology and controls (standard IHC practice). A no-primary section helps identify DAB signal arising from endogenous enzyme or the detection system (standard IHC practice). Treat a clean neuronal pattern as supportive evidence, while recognizing that staining alone does not establish receptor function or isoform identity (standard IHC practice; UniProt P11229).
Boster reagents
Best CHRM1 / Muscarinic acetylcholine receptor M1 IHC Antibodies
A04081 has chromogenic IHC images from paraffin sections of mouse and rat brain and human cerebellum (A04081 image captions). No IF/ICC data are listed (catalog applications and image list).
Real IHC data
Anti-Muscarinic Acetylcholine Receptor 1/CHRM1 Antibody ®
Cat # A04081
Only A04081 will render; it is listed for IHC and reacts with human, mouse, and rat (catalog applications and reactivity). Its IHC captions document paraffin sections of mouse and rat brain and human cerebellum (A04081 image captions).
Which to pick: Choose A04081 for paraffin-section IHC, supported by its own tissue images (A04081 IHC image captions); the fixative is unreported (A04081 IHC image captions). For cross-species work, its IHC images cover human, mouse, and rat (A04081 IHC image captions). A04081 is rabbit-derived with unreported clonality (catalog host and clone fields), and no IF/ICC application or image is listed, so there is no validated IF/ICC choice here (catalog applications and IF image list).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry P11229 (ACM1_HUMAN, Muscarinic acetylcholine receptor M1).
- Human Protein Atlas. CHRM1 tissue IHC expression (reliability: Enhanced).
- Human Protein Atlas. CHRM1 subcellular location (ICC-IF): Membrane.
- Human Protein Atlas. CHRM1 antibody validation summary (1 antibodies).
- Muscarinic acetylcholine receptor M1 mediates prostate cancer cell migration and invasion through hedgehog signaling. Asian journal of andrology 2018 — PMC6219293.
- Autophagy Induced by Muscarinic Acetylcholine Receptor 1 Mediates Migration and Invasion Targeting Atg5 via AMPK/mTOR Pathway in Prostate Cancer. Journal of oncology 2022 — PMC9203210.
- Normal and Pathological Tau Uptake Mediated by M1/M3 Muscarinic Receptors Promotes Opposite Neuronal Changes. Frontiers in cellular neuroscience 2019 — PMC6737038.
- The decrease in hippocampal transient receptor potential M2 (TRPM2) channel and muscarinic acetylcholine receptor 1 (CHRM1) is associated with memory loss in a surgical menopause rat model. Archives of medical science : AMS 2021 — PMC7811316.
- PubMed PMID:3697105 — UniProt-cited evidence.
- PubMed PMID:2336407 — UniProt-cited evidence.
- PubMed PMID:3443095 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for CHRM1 (Muscarinic acetylcholine receptor M1). Expected localisation Neuronal cytoplasm observed; membrane expected (HPA tissue IHC; UniProt). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet A04081). Validated IHC antibody: A04081 at 0.5-1μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Cerebellum (Molecular layer cells - cytoplasm/membrane); negative Adipose tissue. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded mouse brain tissue; fixative not specified (datasheet A04081); 2. Fixation: Image fixative and duration unreported (datasheet A04081); 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 A04081); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet A04081); 8. Primary antibody: Rabbit anti-CHRM1, 0.5-1μg/ml (datasheet A04081); 9. Primary incubation: Overnight at 4 °C (datasheet A04081). Watch for: Fixation: Keep paraffin-section fixation consistent across samples (standard IHC practice; not target-specific); Caveat: Staining has medium consistency with RNA expression (HPA tissue IHC); Isoform / epitope: 2 isoforms; extracellular versus cytoplasmic epitope coverage is unknown (UniProt); Regulation: No expression regulator is annotated (UniProt). Evidence: UniProt P11229, HPA tissue IHC · Enhanced, HPA ICC-IF · Membrane, Datasheet A04081, PMC6219293, PMC9203210. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/CHRM1/immunohistochemistry-ihc-guide.