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PMEL / Melanocyte protein PMEL · IHC design guide
Design Immunohistochemistry for PMEL
Plan chromogenic PMEL IHC in paraffin sections using skin melanocytes as a positive reference (HPA tissue IHC). Assess cytoplasmic staining while accounting for melanin pigment and PMEL processing when interpreting the result (HPA tissue IHC; UniProt; standard IHC practice).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
PMEL 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 | Melanocyte cytoplasm (HPA tissue IHC) | |
| Staining pattern | Selective cytoplasmic staining in melanocytes (HPA tissue IHC) | |
| Antigen retrieval | Citrate pH 6.0 HIER, 95–98 °C, 20 min (rule: cytoplasmic / membrane antigen) | |
| Positive control | Skin | |
| 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 | Melanin may obscure brown chromogen (UniProt; standard IHC practice) | |
| Regulation | Higher with proliferation and in melanoma (UniProt) | |
| Isoform / epitope | 5 isoforms; cleavage separates M-alpha from the cytoplasmic tail (UniProt) |
Section 1
Recommended PMEL IHC & IF Protocols
The catalog antibody protocol is accompanied by published chromogenic PMEL IHC protocols for mouse distant organs, melanoma tissue, and a human tissue microarray (PMC13609154; PMC5587917; PMC8225232).
| Sample | Paraffin-embedded human melanoma tissue; fixative not specified (datasheet M01262) |
| Fixation | Image fixative and duration unreported (datasheet M01262); 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 monoclonal (clone AHH-16) anti-PMEL, 1:50 (datasheet M01262) |
| 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 | PMEL-positive staining in melanocytes of skin (HPA tissue IHC: High). HPA tissue profile: Selective cytoplasmic expression in melanocytes. No signal in the no-primary control. |
💡Decision noteStart with citrate pH 6.0 HIER at 95–98 °C for 20 min (page antigen retrieval).
Section 2
What Is the Expected PMEL Staining Pattern?
In paraffin-section IHC, expect selective cytoplasmic PMEL staining in melanocytes, with high staining reported in skin melanocytes (HPA tissue IHC: Enhanced; High in melanocytes). PMEL occupies melanosomes and their precursors after passage through the ER and Golgi; it has a membrane-spanning segment at residues 596–616 (UniProt P40967: localization; topology).
| Selective cytoplasmic staining in skin melanocytes, stronger than surrounding cells. | This matches the reported tissue pattern (HPA tissue IHC: selective cytoplasmic expression; High in melanocytes). Score identified melanocytes rather than treating all pigmented areas as positive (standard IHC practice). |
| Predominantly nuclear staining, without a convincing melanocyte cytoplasmic pattern. | A dominant nuclear pattern is unexpected given PMEL's reported membrane and melanosome localization (UniProt P40967: localization; topology). Review the negative control and antibody conditions before interpreting it as PMEL. |
| Staining predominates in cells outside the expected melanocyte population. | HPA reports selective staining in melanocytes (HPA tissue IHC). Consider cross-reactivity or endogenous detection activity; establish the cell identity and compare an appropriate negative control before scoring. |
| Broad, diffuse color obscures cell boundaries or appears across many cell types. | This does not reproduce selective cytoplasmic staining (HPA tissue IHC). Assess background with controls, then review blocking, washing and detection conditions (standard IHC practice). |
| No convincing melanocyte signal in an otherwise evaluable skin section. | This conflicts with the reported high staining in skin melanocytes (HPA tissue IHC). Confirm that melanocytes are present, then check the positive control and run conditions before calling the sample negative. |
💡Expected PMEL appearanceCall the result positive when identifiable skin melanocytes show selective cytoplasmic signal of the reported high staining level (HPA tissue IHC); widespread staining of unrelated cells or predominantly nuclear signal warrants review (HPA tissue IHC; UniProt P40967: localization).
| Tissue and cell context | HPA reports high staining in skin melanocytes, while UniProt describes low expression in quiescent adult melanocytes and higher expression during proliferation and melanoma growth (HPA tissue IHC; UniProt P40967: tissue specificity). Interpret intensity with the specimen context. |
| Processing and antibody epitope | PMEL has processed M-alpha (25–467) and M-beta (470–661) chains, and a transmembrane segment at 596–616 (UniProt P40967: processing; topology). The antibody epitope is not supplied, so fragment recognition and the effect of retrieval cannot be predicted from this record. |
| Strength of the tissue evidence | The HPA tissue profile is Enhanced, indicating high consistency between antibody staining and RNA expression; HPA031649 has Enhanced IHC validation (HPA tissue IHC: reliability; HPA antibodies). These findings support the expected pattern without validating every new specimen or run. |
| IF/ICC Q&A: where should signal localize? | HPA reports mainly ER localization with additional Golgi localization in ICC-IF, with images from SK-MEL-30 (HPA subcellular). This answers the IF localization question; the tissue IHC pattern remains selective cytoplasmic staining in melanocytes (HPA tissue IHC). |
| Situation | Likely cause | Next action |
|---|---|---|
| Skin melanocytes appear negative. | Melanocytes may be absent from the assessed area, or the staining run may have failed; HPA reports high staining in skin melanocytes (HPA tissue IHC). | Verify melanocyte identity on the section and inspect a known-positive control. If that control also fails, review retrieval, antibody incubation and detection as general IHC workflow steps (standard IHC practice). |
| The positive control stains, but the sample is weak. | Expression can vary with melanocyte state; UniProt describes low levels in quiescent adult melanocytes (UniProt P40967: tissue specificity). Weak staining alone does not identify a technical failure. | Compare like cell populations and specimen contexts, and score only localized signal above the run's background (standard IHC practice). Avoid applying a universal intensity cutoff from the HPA skin result. |
| Many unrelated cells stain. | This departs from selective melanocyte staining (HPA tissue IHC) and may reflect cross-reactivity or endogenous detection activity (standard IHC practice). | Compare the appropriate negative control, confirm cell identity, and review blocking and detection conditions before assigning PMEL positivity (standard IHC practice). |
| Brown deposits are difficult to separate from pigment. | Melanocytes contain pigment, which can complicate interpretation of a brown chromogenic signal (standard IHC practice; UniProt P40967: pigmentation function). | Compare the stained section with an appropriate control and inspect signal distribution within identified cells; do not score pigment alone as antibody staining (standard IHC practice). |
| Staining is chiefly nuclear or broadly diffuse. | That pattern differs from HPA's selective cytoplasmic tissue staining and UniProt's organelle localization (HPA tissue IHC; UniProt P40967: localization). | Check the negative control and review antibody and detection conditions. Reassess whether any discrete melanocyte cytoplasmic signal remains (standard IHC practice). |
| Retrieval changes the apparent pattern between runs. | The supplied sources do not establish PMEL-specific fixation or retrieval sensitivity; the antibody epitope is unspecified (UniProt P40967: processing; topology). | Compare runs using the same positive tissue and controls, document retrieval conditions, and retain the condition that yields selective melanocyte cytoplasmic staining with acceptable background (HPA tissue IHC; standard IHC practice). |
Experiment evidence
IHC & IF images showing PMEL staining
M01262 · IHCImmunohistochemical analysis of paraffin-embedded human melanoma, using PMEL17 / GP100 Antibody.
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000185664-PMEL/tissue/cerebral+cortex#imid_17876699
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000185664-PMEL/tissue/colon#imid_17876633
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000185664-PMEL/tissue/liver#imid_17876634
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000185664-PMEL/tissue/kidney#imid_17876627
HPA · ICC-IF SK-MEL-30Human Protein Atlas immunofluorescence, SK-MEL-30, antibody HPA031649; green = PMEL, blue = nucleus, red = microtubules.
HPA · ICC-IF SK-MEL-30Human Protein Atlas immunofluorescence, SK-MEL-30, antibody HPA031649; green = PMEL, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for PMEL IHC & IF
🧪Run skin first: melanocytes should stain strongly (HPA: High in skin melanocytes). Use adipose tissue as the negative tissue, with adipocytes unstained (HPA: Not detected in adipocytes); neighboring non-melanocytic cells in the skin section should provide an internal negative (UniProt P40967 tissue specificity; HPA: High in skin melanocytes).
Positive control tissue: Skin (Melanocytes, HPA High)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show PMEL in SK-MEL-30, with annotated localisation: Endoplasmic reticulum (supported) (HPA subcellular).
Technical controls: Include a no-primary (secondary-only) control, an isotype-matched control appropriate to the primary antibody’s host species and clonality, and a PMEL-knockout biological control where available (standard IHC practice). In pigmented skin, quench endogenous peroxidase for chromogenic detection and distinguish melanin from chromogen; for IF, assess tissue autofluorescence with the no-primary control (standard IHC/IF practice).
⚠️Feasibility: A target-specific fixation window and retrieval dependency are unreported in the supplied evidence; the selected M01262 paraffin-section melanoma caption does not state its fixative (M01262 caption). That caption supports paraffin-section IHC, while the reported ICC-IF images are from SK-MEL-30; the evidence does not establish that frozen sections or IF are easier (M01262 caption; HPA subcellular). Melanin in pigmented skin can complicate interpretation of chromogenic staining and fluorescence (standard IHC/IF practice).
HPA tissue IHC evidence for PMEL
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Enhanced — High 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 |
|---|---|---|---|---|
| Skin | Melanocytes | High | 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 PMEL IHC Tips
Troubleshoot PMEL staining in paraffin sections by checking retrieval, cellular distribution, processing, and controls before interpreting chromogenic signal.
What retrieval should I try when PMEL staining is weak in paraffin sections?
Start PMEL IHC with citrate pH 6.0 heat-induced retrieval at 95–98 °C for 20 min (page retrieval setting). Cool sections consistently before applying the IHC-validated antibody, and compare a short retrieval time series on adjacent sections if signal remains weak (standard IHC practice). Include melanoma as a positive tissue because paraffin-embedded human melanoma was stained with catalog antibody M01262 (M01262 tissue-IHC caption). Assess whether signal appears in the expected cytoplasmic distribution rather than accepting a general increase in brown staining (HPA: selective cytoplasmic expression in melanocytes; standard IHC practice).
Could fixation explain weak or uneven PMEL staining?
Target-specific PMEL sensitivity to fixation is unknown from the supplied evidence; the melanoma caption identifies paraffin embedding but does not state a fixative (M01262 tissue-IHC caption). Record the actual fixative and fixation duration for each specimen, then compare sections processed together with the same citrate pH 6.0 retrieval (standard IHC practice; page retrieval setting). Check whether weak areas track tissue thickness, folds, or processing differences before changing antibody conditions (standard IHC practice). Use a concurrently stained melanoma control to separate a specimen-level problem from a run-level problem, without treating its staining as proof of fixation tolerance (M01262 tissue-IHC caption; standard IHC practice).
Where should convincing PMEL staining appear in tissue?
In tissue IHC, look for selective cytoplasmic staining in melanocytes; the HPA tissue profile reports high staining in skin melanocytes (HPA: selective cytoplasmic expression; HPA: High in skin melanocytes). PMEL also occupies endosomal and melanosomal compartments during maturation, so a cytoplasmic granular pattern can fit its biology (UniProt P40967 subcellular localisation and function). Its transmembrane segment spans residues 596–616, and transient surface localisation has been reported, but isolated diffuse membrane staining needs corroboration (UniProt P40967 topology and subcellular localisation; standard IHC practice). Compare stained cells with tissue morphology and a no-primary control before calling widespread stromal colour PMEL-positive (standard IHC practice).
Why might two PMEL antibodies stain different structures?
Check each antibody’s stated epitope before comparing IHC patterns; PMEL has 5 reported isoforms and undergoes cleavage into M-alpha (25–467) and M-beta (470–661) chains (UniProt P40967 isoforms and processing). An epitope on a released luminal fragment may remain visible in melanosomal material, whereas a cytoplasmic-tail epitope tests a different part of the molecule (UniProt P40967 topology and processing). Glycosylation is annotated at residues 81, 106, 111, 321, and 568, so epitope accessibility warrants experimental checking (UniProt P40967 glycosylation; standard IHC practice). Without an epitope map, do not assign discordant staining to a particular isoform or cleavage product (standard IHC practice).
How should I investigate PMEL localisation with IF alongside tissue IHC?
On the separate IF/ICC workflow, pair PMEL with a distinguishable melanocyte-lineage marker such as MLANA and inspect cellular overlap, while allowing their subcellular patterns to differ (UniProt P40967: MLANA interaction; standard IF practice). Choose a far-red PMEL fluorophore when specimen autofluorescence interferes with shorter wavelengths, and include single-channel controls for bleed-through (standard IF practice). For an antibody recognizing a cytoplasmic-tail epitope, permeabilize the plasma membrane; for a luminal epitope, test access to intracellular organelles as well (UniProt P40967 topology; standard IF practice). The HPA IF record supports ER localisation with additional Golgi localisation, but IF findings require separate validation for interpretation in chromogenic tissue sections (HPA subcellular profile; standard IHC/IF practice).
How can I separate PMEL signal from pigment and chromogenic background?
Examine an unstained section alongside the DAB slide to identify native pigment before scoring brown PMEL signal (standard IHC practice). PMEL contributes to melanosome morphogenesis and pigmentation, making pigment-rich regions particularly important to check (UniProt P40967 function; standard IHC practice). Run a no-primary control, block endogenous peroxidase, and assess whether residual colour follows tissue edges, folds, or damaged areas (standard IHC practice). If pigment obscures DAB, use an alternative chromogen with clear visual separation and confirm that any new signal remains in the expected melanocytic cytoplasm (standard IHC practice; HPA: selective cytoplasmic expression in melanocytes).
How should I score PMEL IHC across specimens? ⚠ ANSWER MARKED FOR VERIFICATION
Define the scoring population from morphology before measuring PMEL, and keep retrieval and detection conditions constant across compared sections (standard IHC practice). Record the percentage of positive melanocytic cells and an H-score from staining intensity and positive-cell fraction; report the scoring rule with the results (standard IHC practice). For spatial questions, count positive cells per mm² of viable tissue or a predefined region, excluding folds and necrosis (standard IHC practice). Normalize cell-based scores to the melanocytic population or its estimated area so differing cell composition does not masquerade as altered PMEL expression (HPA: selective cytoplasmic expression in melanocytes; standard IHC practice).
When is a positive PMEL IHC result credible?
A credible result combines staining in morphologically appropriate melanocytic cells with the expected cytoplasmic distribution and a clean negative control (HPA: selective cytoplasmic expression in melanocytes; standard IHC practice). Melanoma staining is plausible because PMEL is reported as overexpressed in melanomas and catalog antibody M01262 stained a paraffin-embedded human melanoma specimen (UniProt P40967 tissue specificity; M01262 tissue-IHC caption). Treat diffuse staining in unrelated cells, edge-only colour, and necrotic regions as possible artefacts requiring review (standard IHC practice). Compare with no-primary and peroxidase-block controls to distinguish antibody-associated staining from endogenous enzyme activity, and inspect unstained tissue for pigment (standard IHC practice).
Boster reagents
Best PMEL / Melanocyte protein PMEL IHC Antibodies
M01262 has real IHC data from paraffin-embedded human melanoma (catalog image caption); IF data are absent (catalog).
Real IHC data
Anti-PMEL17 / GP100 Rabbit Monoclonal Antibody
Cat # M01262
M01262 is listed for human IHC (catalog applications and reactivity). Its IHC image shows paraffin-embedded human melanoma (catalog image caption); no IF image is supplied (catalog).
Which to pick: For tissue IHC, choose M01262, a human-reactive rabbit monoclonal with an IHC image from paraffin-embedded human melanoma (catalog; catalog image caption). The caption does not report the fixative (catalog image caption). No listed SKU is supported here for IF/ICC or other species (catalog applications, IF images and reactivity).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry P40967 (PMEL_HUMAN, Melanocyte protein PMEL).
- Human Protein Atlas. PMEL tissue IHC expression (reliability: Enhanced).
- Human Protein Atlas. PMEL subcellular location (ICC-IF): Mainly localized to the endoplasmic reticulum. In addition localized to the Golgi apparatus..
- Human Protein Atlas. PMEL antibody validation summary (1 antibodies).
- Chemotherapy Supports Cancer Cell Dissemination in a Melanoma Preclinical Model. Asian Pacific journal of cancer prevention : APJCP 2026 — PMC13609154.
- Effects of microRNA-136 on melanoma cell proliferation, apoptosis, and epithelial-mesenchymal transition by targetting PMEL through the Wnt signaling pathway. Bioscience reports 2017 — PMC5587917.
- PMEL as a Prognostic Biomarker and Negatively Associated With Immune Infiltration in Skin Cutaneous Melanoma (SKCM). Journal of immunotherapy (Hagerstown, Md. : 1997) 2021 — PMC8225232.
- A Lower Irradiation Dose of 308 nm Monochromatic Excimer Light Might Be Sufficient for Vitiligo Treatment: A Novel Insight Gained from In Vitro and In Vivo Analyses. International journal of molecular sciences 2021 — PMC8508796.
- PubMed PMID:1924386 — UniProt-cited evidence.
- PubMed PMID:8179825 — UniProt-cited evidence.
- PubMed PMID:7519602 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for PMEL (Melanocyte protein PMEL). Expected localisation Melanocyte cytoplasm (HPA tissue IHC). Antigen retrieval: Citrate pH 6.0 HIER, 95–98 °C, 20 min (rule: cytoplasmic / membrane antigen). Validated IHC antibody: M01262 at 1:50 (the product's own IHC validation image is shown). Controls (HPA): positive Skin (Melanocytes); negative Adipose tissue. IHC workflow; specimen preparation unspecified. Protocol steps: 1. Sample: Paraffin-embedded human melanoma tissue; fixative not specified (datasheet M01262); 2. Fixation: Image fixative and duration unreported (datasheet M01262); 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 monoclonal (clone AHH-16) anti-PMEL, 1:50 (datasheet M01262); 9. Primary incubation: Overnight at 4 °C (standard). Watch for: Fixation: Keep fixation consistent across sections. (standard IHC practice; not target-specific); Caveat: Melanin may obscure brown chromogen (UniProt; standard IHC practice); Isoform / epitope: 5 isoforms; cleavage separates M-alpha from the cytoplasmic tail (UniProt); Regulation: Higher with proliferation and in melanoma (UniProt). Evidence: UniProt P40967, HPA tissue IHC · Enhanced, HPA ICC-IF · Mainly localized to the endoplasmic reticulum. In addition localized…, Datasheet M01262, PMC13609154, PMC5587917. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/PMEL/immunohistochemistry-ihc-guide.