CHRM1 / Muscarinic acetylcholine receptor M1 · IHC design guide

Design Immunohistochemistry for CHRM1

Plan CHRM1 chromogenic IHC in paraffin sections using human cerebellum as a positive tissue (HPA tissue IHC; datasheet A04081). Interpret neuronal cytoplasmic staining alongside CHRM1’s annotated cell membrane location (HPA tissue IHC; UniProt).

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

Immunohistochemistry protocol sheet for CHRM1 (IHC for CHRM1): expected localisation Neuronal cytoplasm (HPA tissue IHC); cell membrane (UniProt), antibody A04081, validated IHC image, and IHC protocol steps — Printable **CHRM1** IHC protocol sheet — expected localisation Neuronal cytoplasm (HPA tissue IHC); cell membrane (UniProt), antibody A04081, controls and protocol steps. Open the full CHRM1 IHC guide →

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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 (HPA tissue IHC); cell membrane (UniProt)
	Staining pattern	Pyramidal neurons and Purkinje cells: cytoplasmic staining (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 fixation consistent across sections (standard IHC practice; not target-specific). Selected-image fixative and duration unreported (datasheet A04081); verify before use.
	Caveat	Cytoplasmic staining can complicate membrane interpretation (HPA tissue IHC; UniProt)
	Regulation	Expression regulation is not annotated (UniProt)
	Isoform / epitope	2 isoforms; check whether the epitope is extracellular or cytoplasmic (UniProt)

Section 1

Recommended CHRM1 IHC & IF Protocols

The catalog antibody has an IHC-P protocol with EDTA pH 8.0 retrieval (datasheet: A04081). The published IHC protocols below provide prostate tumor and rat hippocampal tissue examples (PMC6219293; PMC9203210; PMC7811316).

Recommended immunohistochemistry (IHC-P) protocol parameters
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 EDTA pH 8.0 heat retrieval for the catalog antibody (datasheet: A04081); published protocols used citrate retrieval with different antibodies (PMC9203210; PMC7811316).

Section 2

What Is the Expected CHRM1 Staining Pattern?

CHRM1 is a seven-pass receptor at the cell and postsynaptic membranes (UniProt P11229 topology; UniProt P11229 subcellular location). In paraffin-section IHC, HPA reports cytoplasmic staining in pyramidal neurons and Purkinje cells, with high cytoplasm/membrane staining in cerebellar molecular-layer cells and medium staining in cortical and hippocampal neurons (HPA tissue IHC). HPA rates the tissue pattern Enhanced, while noting medium consistency with RNA data (HPA tissue IHC).

What am I looking at on my slide?
Neuronal staining with a membrane-associated outline and some cytoplasmic signal.	This fits CHRM1 membrane topology and HPA’s observed neuronal cytoplasmic staining; the two descriptions need not look identical in a tissue section (UniProt P11229 topology; HPA tissue IHC). Compare the distribution across cells, not the membrane edge alone (general IHC practice).
Strong nuclear staining dominates the section.	A predominantly nuclear pattern does not match the reported membrane location or neuronal cytoplasmic IHC profile (UniProt P11229 subcellular location; HPA tissue IHC). Treat it as suspect until a control and a different detection condition reproduce it (general IHC practice).
Adipocytes stain as strongly as the neuronal positive control.	HPA reports no detectable CHRM1 staining in adipocytes from adipose tissue (HPA tissue IHC). This pattern raises concern for cross-reactivity or endogenous detection activity; it does not by itself identify which is responsible (general IHC practice).
Color is spread evenly across cells and surrounding tissue.	Diffuse staining that obscures cell boundaries cannot establish the HPA neuronal pattern (HPA tissue IHC). Compare a no-primary control and inspect blocking, washes, and chromogen development for nonspecific background (general IHC practice).
No staining appears in a cerebral cortex or hippocampus control.	HPA reports medium neuronal staining in these tissues, so a blank section calls for a run-level check before interpreting test samples as negative (HPA tissue IHC). Examine tissue preservation, primary-antibody use, retrieval, and detection controls (general IHC practice).

💡Expected CHRM1 appearanceCall a result positive when neuronal cytoplasm and membrane-associated regions stain, with high signal in cerebellar molecular-layer cells or medium signal in cortical or hippocampal neurons; isolated strong nuclear or adipocyte staining is suspect (HPA tissue IHC; UniProt P11229 subcellular location).

How each factor affects the staining
Which compartment should guide scoring?	CHRM1 has seven transmembrane segments and a postsynaptic membrane annotation, while HPA describes cytoplasmic neuronal IHC signal (UniProt P11229 topology; UniProt P11229 subcellular location; HPA tissue IHC). Score the observed cell pattern alongside membrane association; do not require a continuous membrane rim.
How strong is the tissue reference?	HPA labels its IHC pattern Enhanced and cites external characterization, but reports only medium consistency between staining and RNA expression (HPA tissue IHC). Use its positive and negative cell examples as benchmarks, not as proof that every section or antibody will match exactly.
Can sequence features predict retrieval or isoform staining?	UniProt lists two isoforms and extracellular glycosylation sites at residues 2 and 12 (UniProt P11229). No antibody epitope or target-specific retrieval response is supplied; these annotations cannot establish which isoform stains or which retrieval condition works.
IF/ICC: is the same pattern independently confirmed?	HPA summarizes CHRM1 as membrane-localized for ICC-IF but provides no main-location call or cell-line images in the supplied record (HPA subcellular ICC-IF). This supports a membrane expectation, not an image-verified IF pattern for a particular cell type.

Why is my staining missing, weak or wrong?
Situation	Likely cause	Next action
The neuronal positive control is blank.	The run may have lost detectable signal despite medium cortical or hippocampal neuronal staining reported by HPA (HPA tissue IHC).	Check the control section, primary-antibody step, retrieval conditions, and chromogenic detection with the run controls (general IHC practice). Do not assign the blank test section a biological negative call yet.
Cerebellar staining is weaker than expected.	HPA reports high staining specifically in molecular-layer cells, rather than a uniform high signal throughout cerebellum (HPA tissue IHC).	Confirm that the scored region contains the relevant cells, then compare it with the positive control from the same run (HPA tissue IHC; general IHC practice).
Nuclei dominate the stain.	That compartment conflicts with the membrane annotation and HPA neuronal cytoplasmic profile (UniProt P11229 subcellular location; HPA tissue IHC).	Review the no-primary control and staining distribution; optimize blocking and detection if background is present (general IHC practice). Avoid counting nuclear-only cells as CHRM1 positive.
Adipocytes or unrelated cells are strongly colored.	HPA lists adipocytes in adipose tissue as not detected, so this warrants a specificity check (HPA tissue IHC). Cross-reactivity and endogenous detection activity are possible explanations (general IHC practice).	Compare a no-primary control with the stained section, assess endogenous detection activity, and verify the neuronal control pattern before scoring (general IHC practice).
The section has widespread hazy color.	Broad background can conceal the neuronal pattern documented by HPA (HPA tissue IHC). Excess detection signal or incomplete washing are possible workflow causes (general IHC practice).	Compare no-primary and tissue controls; review blocking, washing, primary dilution, and chromogen development (general IHC practice). Reassess cell-level localization after background is reduced.
Membrane outlines are hard to distinguish from cytoplasm.	HPA reports cytoplasmic neuronal staining, while UniProt places the receptor in membranes; a crisp rim is therefore an unreliable sole criterion (HPA tissue IHC; UniProt P11229 subcellular location).	Score the named neuronal populations and relative signal against run controls. Record cytoplasmic and membrane-associated appearances separately when visible (HPA tissue IHC; general IHC practice).

Source: UniProt P11229 Human Protein Atlas tissue Human Protein Atlas subcellular

Experiment evidence

IHC & IF images showing CHRM1 staining

IHC analysis of CHRM1 using anti-CHRM1 antibody (A04081). CHRM1 was detected in paraffin-embedded section of mouse brain tissue. Heat mediated antigen retrieval was performed in EDTA buffer (pH8.0, epitope retrieval solution). The tissue section was blocked with 10% goat serum. The tissue section was then incubated with 1μg/ml rabbit anti-CHRM1 Antibody (A04081) overnight at 4°C. Biotinylated goat anti-rabbit IgG was used as secondary antibody and incubated for 30 minutes at 37°C. The tissue section was developed using Strepavidin-Biotin-Complex (SABC) (Catalog # SA1022) with DAB as the chromogen.

A04081 · IHCIHC analysis of CHRM1 using anti-CHRM1 antibody (A04081). CHRM1 was detected in paraffin-embedded section of mouse brain tissue. Heat mediat

IHC analysis of CHRM1 using anti-CHRM1 antibody (A04081). CHRM1 was detected in paraffin-embedded section of rat brain tissue. Heat mediated antigen retrieval was performed in EDTA buffer (pH8.0, epitope retrieval solution). The tissue section was blocked with 10% goat serum. The tissue section was then incubated with 1μg/ml rabbit anti-CHRM1 Antibody (A04081) overnight at 4°C. Biotinylated goat anti-rabbit IgG was used as secondary antibody and incubated for 30 minutes at 37°C. The tissue section was developed using Strepavidin-Biotin-Complex (SABC) (Catalog # SA1022) with DAB as the chromogen.

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 assess staining in molecular layer cells, where CHRM1 is reported as High with cytoplasmic/membrane staining (HPA: cerebellum, High). Use adipose tissue as the negative tissue, focusing on adipocytes reported as Not detected (HPA: adipose tissue); on the cerebellum slide, neighboring cells without specific staining should remain at background level (standard IHC practice).

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 concentration-matched rabbit IgG isotype control matched to the primary antibody’s clonality where known; and CHRM1 knockout tissue as a biological negative (A04081 caption: rabbit primary; standard IHC practice). Block endogenous peroxidase and check for endogenous biotin because the illustrated method uses a streptavidin–biotin complex with DAB (A04081 caption); assess brain autofluorescence if using IF (standard IF practice).

⚠️Feasibility: A target-specific fixation window or fixation effect is unreported, and the selected A04081 paraffin-section caption does not state a fixative (A04081 caption). That IHC example uses heat-mediated retrieval in EDTA at pH 8.0, but the evidence does not establish whether retrieval is required under other conditions (A04081 caption). The supplied evidence does not establish whether frozen sections or IF are easier; brain autofluorescence can complicate IF interpretation (standard IF 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 workflow as the starting point, then assess staining against CHRM1 topology and the reported neuronal pattern.

How should I optimize antigen retrieval for CHRM1 in paraffin sections?

Start with heat-mediated antigen retrieval in EDTA buffer at pH 8.0 (datasheet A04081). Keep the retrieval method consistent while comparing sections, because changes in heating and cooling can alter staining across a run (standard IHC practice). The catalog image used paraffin-embedded mouse brain, followed by 10% goat serum block and 1 µg/mL primary antibody overnight at 4°C (datasheet A04081). If staining remains weak, adjust retrieval duration on matched sections before considering another buffer; assess signal in neuronal compartments alongside tissue preservation and background (standard IHC practice; HPA: neuronal staining in cerebral cortex and hippocampus).

Could fixation explain weak or uneven CHRM1 staining?

The catalog caption identifies paraffin-embedded mouse brain but does not state its fixative, so CHRM1-specific fixation sensitivity is unknown for this workflow (datasheet A04081). Record the fixative, fixation duration, specimen size and processing history for each section; compare matched specimens processed together when investigating weak staining (standard IHC practice). Use the stated EDTA retrieval at pH 8.0 and 1 µg/mL antibody overnight at 4°C as consistent starting conditions (datasheet A04081). If only heavily processed areas lose signal, examine morphology and a control processed in parallel before assigning the difference to CHRM1 expression (standard IHC practice).

What staining pattern is plausible for CHRM1 in brain sections?

CHRM1 is annotated at the cell and postsynaptic membranes, with 7 transmembrane segments (UniProt P11229 topology and subcellular location). Tissue IHC also reports cytoplasmic staining in pyramidal neurons and Purkinje cells, and cytoplasm or membrane staining in cerebellar molecular layer cells (HPA: tissue IHC profile and cerebellum). In chromogenic sections, assess whether staining follows neuronal cell bodies and processes rather than judging a membrane rim alone; compare adjacent structures under the same counterstain (standard IHC practice; HPA: neuronal staining in cerebral cortex and hippocampus). Diffuse staining across unrelated cell types deserves background controls before interpretation as receptor localisation (standard IHC practice).

How do CHRM1 isoforms and epitope orientation affect IHC interpretation?

UniProt lists 2 CHRM1 isoforms, but the supplied evidence does not map this antibody’s epitope or establish which isoforms it detects (UniProt P11229 isoforms; datasheet A04081). CHRM1 has extracellular segments at residues 1–22 and 165–185, plus a long cytoplasmic segment at 210–366 (UniProt P11229 topology). Its N-terminal glycosylation sites at residues 2 and 12 and annotated phosphorylation sites are reasons to avoid assuming identical epitope access across preparations (UniProt P11229 modifications; standard IHC practice). If staining changes with processing, first establish the antibody’s epitope and compare matched sections before assigning the difference to an isoform (standard IHC practice).

How would I assess CHRM1 by multiplex immunofluorescence?

Treat IF as a separate assay requiring validation: the supplied catalog evidence documents chromogenic staining in paraffin-embedded mouse brain, while HPA lists no ICC/IF cell images (datasheet A04081; HPA: subcellular record). Multiplex CHRM1 with a validated neuronal marker to identify the expected cell population, and include single-label controls for channel bleed-through (HPA: neuronal tissue IHC profile; standard IF practice). Choose fluorophores after inspecting unstained tissue for autofluorescence, favoring channels with a clear signal-to-background separation (standard IF practice). Set permeabilisation according to the mapped antibody epitope: a cytoplasmic epitope requires access across the membrane, whereas an accessible extracellular epitope may not (UniProt P11229 topology; standard IF practice).

How can I troubleshoot diffuse brown staining in CHRM1 IHC?

Compare sections processed without primary antibody and inspect where brown signal appears relative to neuronal morphology (standard chromogenic IHC practice; HPA: neuronal tissue IHC profile). The catalog workflow used 10% goat serum, a biotinylated secondary antibody, a streptavidin–biotin complex and DAB; each detection step should be checked with appropriate controls (datasheet A04081; standard IHC practice). Include a peroxidase block and assess endogenous biotin when using this detection system, especially if staining persists without primary antibody (standard IHC practice). Titrate the 1 µg/mL primary starting concentration on matched sections and compare background with signal in expected neuronal cells (datasheet A04081; HPA: neuronal staining in cerebral cortex and hippocampus).

How should I quantify CHRM1 staining across paraffin sections? ⚠ ANSWER MARKED FOR VERIFICATION

Define the neuronal population and anatomical region before scoring, then apply the same segmentation and intensity thresholds to every section (HPA: neuronal tissue IHC profile; standard quantitative IHC practice). Report an H-score or the percentage of positive cells, and record the number of evaluable neurons so changes in cell abundance do not masquerade as changes in staining (standard quantitative IHC practice). For regional signal, measure positive area or cell density per mm² and normalise to evaluable tissue area, excluding folds and damaged edges by a fixed rule (standard quantitative IHC practice). Compare sections processed with the same EDTA pH 8.0 retrieval and detection conditions (datasheet A04081; standard quantitative IHC practice).

When is CHRM1 staining convincing rather than an artefact?

Give the most weight to reproducible neuronal staining in the expected brain regions, interpreted with the annotated membrane location and reported cytoplasmic or membrane tissue pattern (HPA: neuronal tissue IHC profile and cerebellum; UniProt P11229 subcellular location). Review unexpected signal in unrelated cells against no-primary controls, since diffuse staining alone does not establish receptor expression (standard IHC practice). Exclude section edges, folds and necrotic areas from interpretation, and investigate brown signal caused by endogenous enzyme activity with a peroxidase-block control (standard chromogenic IHC practice). HPA rates its tissue staining Enhanced but reports only medium consistency with RNA expression, so confirm consequential findings with an independent specificity control (HPA: reliability description; standard IHC practice).

Boster reagents

Best CHRM1 / Muscarinic acetylcholine receptor M1 IHC Antibodies

A04081 has CHRM1 IHC images from paraffin sections of mouse brain, rat brain, and human cerebellum (A04081 IHC captions). No IF images are supplied (catalog: IF image alts).

Real IHC data

Anti-Muscarinic Acetylcholine Receptor 1/CHRM1 Antibody ®

Cat # A04081

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A04081 is listed for IHC and for Human, Mouse, and Rat reactivity (catalog: A04081 applications and reactivity). Its IHC captions document paraffin sections of mouse brain, rat brain, and human cerebellum (A04081 IHC captions).

Which to pick: Choose A04081 for paraffin-section tissue IHC; its captions show mouse and rat brain and human cerebellum, but do not report the fixative (A04081 IHC captions). For IF/ICC, no listed SKU has an IF/ICC application or IF image (catalog: A04081 applications and IF image alts). For work across the three listed species, A04081 is the available choice based on its Human, Mouse, and Rat reactivity; it is a rabbit antibody with no clone specified (catalog: A04081 reactivity, host, and clone).

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.