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MFSD1 / Lysosomal dipeptide transporter MFSD1 · IHC design guide
Design Immunohistochemistry for MFSD1
Plan chromogenic MFSD1 IHC in paraffin sections using 10 μg/mL as a starting antibody concentration (datasheet). Assess cytoplasmic staining in immune-cell subsets (HPA tissue IHC), while treating lysosomal membrane localization as a molecular expectation (UniProt).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
MFSD1 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 | Cytoplasmic staining in immune-cell subsets (HPA tissue IHC) | |
| Staining pattern | Cytoplasmic staining in subsets of immune cells (HPA tissue IHC) | |
| Antigen retrieval | Citrate pH 6.0 HIER, 95–98 °C, 20 min (rule: cytoplasmic / membrane antigen) | |
| Positive control | Appendix+4 more · see all | |
| Negative control | Adipose tissue+4 more · see all |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Keep fixation consistent across sections (standard IHC practice; not target-specific) | |
| Caveat | Catalog antibody IHC validated in rat, not human (datasheet) | |
| Regulation | No expression regulator annotated (UniProt) | |
| Isoform / epitope | 6 isoforms (UniProt); epitope unmapped (datasheet) |
Section 1
Recommended MFSD1 IHC & IF Protocols
The catalog antibody’s IHC-P protocol is accompanied by one published chromogenic MFSD1 protocol using free-floating mouse brain sections (PMC5321710).
| Sample | Tissue sections; selected-image fixative not specified (standard IHC workflow) |
| Fixation | Image fixative and duration unreported (datasheet A17695); verify before use. |
| Sectioning | 4–5 µm sections on charged slides (standard) |
| Deparaffinisation | Xylene, graded ethanol series to water (standard) |
| Antigen retrieval | Heat-induced epitope retrieval in citrate buffer, pH 6.0, 20 min at 95–98 °C (standard rule: cytoplasmic / membrane antigen) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% normal serum of the secondary host, 30 min, room temperature (standard) |
| Primary antibody | Rabbit anti-MFSD1, 10 μg/mL (datasheet A17695) |
| 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 | MFSD1-positive staining in lymphoid tissue of appendix (HPA tissue IHC: High). HPA tissue profile: Cytoplasmic expression mainly in subsets of immune cells in most tissues. No signal in the no-primary control. |
💡Decision noteFor paraffin sections, start with citrate pH 6.0 retrieval at 95–98 °C for 20 min (page retrieval). The free-floating protocol does not report retrieval (PMC5321710).
Section 2
What Is the Expected MFSD1 Staining Pattern?
MFSD1 is a lysosomal membrane transporter with 12 transmembrane segments (UniProt Q9H3U5 topology). In tissue IHC, expect cytoplasmic staining mainly in subsets of immune cells, with high staining also reported in specific ciliated, decidual and Leydig cells (HPA tissue IHC). HPA rates its tissue IHC profile Approved, with medium consistency between antibody staining and RNA expression (HPA tissue IHC).
| Cytoplasmic signal appears in selected immune cells; germinal center cells stain strongly. | This fits the reported tissue profile and High staining in lymph node and tonsil germinal center cells (HPA tissue IHC). Score the named cell population, since an unstained neighboring cell does not invalidate a positive result in a mixed tissue. |
| Strong nuclear staining dominates the section. | A nuclear dominant pattern conflicts with the lysosomal membrane annotation and the reported cytoplasmic tissue IHC pattern (UniProt Q9H3U5; HPA tissue IHC). Treat it as suspect; compare the control tissue, detection only control and nuclear counterstain before assigning MFSD1 positivity. |
| Strong staining appears in a cell population reported as Not detected. | For example, HPA reports adipocytes as Not detected (HPA tissue IHC). Reproducible staining there warrants a specificity check, including omission of primary antibody to assess detection background. An HPA Not detected call is a reference observation, not proof that every specimen must be negative. |
| Color spreads across stroma, empty spaces or many unrelated cell types. | That distribution is difficult to reconcile with HPA’s selective tissue profile (HPA tissue IHC). Review the detection only control for endogenous enzyme activity or nonspecific reagent binding; compare staining with cellular morphology before scoring any diffuse color as MFSD1. |
| A known positive tissue shows no convincing cellular signal. | Check a documented High population, such as tonsil germinal center cells or testis Leydig cells (HPA tissue IHC). Confirm the expected cells are present, then review antigen retrieval, primary antibody application and chromogen development as general IHC workflow checks. One negative section does not establish absent MFSD1. |
💡Expected MFSD1 appearanceCall a tissue IHC result positive when selected cells show clear cytoplasmic staining, potentially High in HPA listed positive populations; broad acellular color or dominant nuclear signal is suspect (HPA tissue IHC; UniProt Q9H3U5).
| Membrane topology | MFSD1 has 12 transmembrane segments and is annotated at the lysosome membrane (UniProt Q9H3U5 topology and subcellular location). Interpret chromogenic tissue staining at the cellular, cytoplasmic level; the supplied sources do not establish a target specific retrieval condition or predict a resolvable lysosomal pattern on every section. |
| Cell population within the tissue | HPA reports cytoplasmic expression mainly in subsets of immune cells, alongside High staining in specified ciliated, decidual and Leydig populations (HPA tissue IHC). Choose and score the documented population rather than averaging staining across an entire tissue or treating adjacent unstained cells as assay failure. |
| Evidence strength | HPA calls the tissue IHC profile Approved but describes medium consistency with RNA expression (HPA tissue IHC). Its listed High and Not detected calls guide control selection; they do not by themselves verify the identity of every positive cell or establish a universal negative tissue. |
| Assay dependent localisation | HPA reports mainly plasma membrane, with additional cytosol, in ICC-IF (HPA subcellular ICC-IF), while UniProt places MFSD1 at the lysosome membrane (UniProt Q9H3U5). That ICC-IF observation belongs to the separate IF/ICC guide; do not use it as the required chromogenic tissue IHC pattern. |
| Isoform and epitope information | UniProt lists 6 isoforms (UniProt Q9H3U5). The supplied evidence gives no antibody epitope or isoform specific staining result, so isoform coverage cannot be inferred. Avoid explaining an unexpected positive or negative cell solely through alternative splicing. |
| Situation | Likely cause | Next action |
|---|---|---|
| Tonsil germinal center cells are unstained. | The expected High population may be absent from the examined area, or an IHC workflow step may have failed (HPA tissue IHC; general IHC practice). | Locate germinal centers on the counterstained section; then check retrieval, primary incubation and detection against the assay’s established controls. Do not infer MFSD1 absence until the expected cells and assay performance are verified. |
| Adipocytes stain as strongly as the positive control. | This disagrees with HPA’s Not detected call for adipocytes; nonspecific binding or detection background is possible (HPA tissue IHC; general IHC practice). | Compare the same cell type across sections, inspect morphology and run a detection only control. Record the disagreement as unresolved if staining persists; HPA’s reference call alone cannot identify the cause. |
| Most of the section has a faint, even tint. | Diffuse tint can arise from chromogenic detection background rather than the selective cytoplasmic profile reported for MFSD1 (general IHC practice; HPA tissue IHC). | Inspect a detection only control and review blocking, washing and chromogen development under the assay’s standard procedure. Score distinct cellular signal separately from the overall tint. |
| Only nuclei appear strongly positive. | A nuclear dominant result conflicts with UniProt’s lysosome membrane location and HPA’s cytoplasmic tissue profile (UniProt Q9H3U5; HPA tissue IHC). | Compare with the nuclear counterstain and a documented High tissue population; check a detection only control before calling the nuclear signal specific. |
| A bronchus section has signal near cilia but little signal elsewhere. | HPA reports High staining in bronchial ciliated cells at ciliary rootlets; a restricted pattern can therefore be expected (HPA tissue IHC). | Confirm ciliated cell morphology and score that compartment specifically. Avoid treating weak staining in unrelated neighboring cells as a failed run when the documented population stains. |
| An ICC-IF image looks membrane associated while tissue IHC looks cytoplasmic. | Those descriptions come from different HPA assays; ICC-IF lists plasma membrane and cytosol, while tissue IHC reports a cytoplasmic profile (HPA subcellular ICC-IF; HPA tissue IHC). | Assess the paraffin section against tissue IHC controls and cell morphology. Use the separate IF/ICC guide for fluorescence localisation; the difference alone does not establish a failed IHC run. |
Experiment evidence
IHC & IF images showing MFSD1 staining
A17695 · IHCImmunohistochemistry of MFSD1 in rat lung tissue with MFSD1 antibody at 10 μg/mL.
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000118855-MFSD1/tissue/cerebral+cortex#imid_20101949
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000118855-MFSD1/tissue/colon#imid_20105179
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000118855-MFSD1/tissue/liver#imid_20105188
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000118855-MFSD1/tissue/kidney#imid_20105173
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA065858; green = MFSD1, blue = nucleus, red = microtubules.
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA065858; green = MFSD1, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for MFSD1 IHC & IF
🧪Run lymph node first; germinal center cells should stain (HPA: High in germinal center cells). Use adipose tissue as a negative comparator, assessing adipocytes specifically (HPA: Not detected in adipocytes); on the lymph-node slide, cells outside germinal centers can serve as internal negative comparators only if independently verified negative, and should retain counterstain without specific chromogen (standard IHC practice).
Positive control tissue: Appendix (Lymphoid tissue, HPA High)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show MFSD1 in A-431, BJ [Human fibroblast], U2OS, with annotated localisation: Plasma membrane (approved) (HPA subcellular).
Technical controls: Include a no-primary (secondary-only) control, an isotype control matched to the primary antibody’s host species and clonality, and MFSD1 knockout tissue or a peptide-block control if the immunizing peptide is available (standard IHC practice). Quench endogenous peroxidase in lymph-node sections to limit chromogenic background from leukocytes (standard IHC practice).
⚠️Feasibility: A target-specific fixation window or fixation effect is unreported in the supplied evidence; the A17695 rat-lung IHC caption does not state a fixative (caption: fixative not stated). Antigen-retrieval dependency is also unreported, so assess retrieval conditions with matched positive and negative paraffin sections (supplied evidence; standard IHC practice). The supplied evidence does not establish whether frozen sections or IF are easier; leukocyte-associated endogenous peroxidase is a potential background artefact in lymph-node IHC (standard IHC practice).
HPA tissue IHC evidence for MFSD1
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Approved — Medium 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 |
|---|---|---|---|---|
| Appendix | Lymphoid tissue | High | Protein (IHC) | HPA → |
| Bronchus | Ciliated cells (ciliary rootlets) | High | Protein (IHC) | HPA → |
| Fallopian tube | Ciliated cells (ciliary rootlets) | High | Protein (IHC) | HPA → |
| Lymph node | Germinal center cells | High | Protein (IHC) | HPA → |
| Nasopharynx | Ciliated cells (ciliary rootlets) | High | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Adipose tissue | Adipocytes | Not detected | Protein (IHC) | HPA → |
| Caudate | Glial cells | Not detected | Protein (IHC) | HPA → |
| Cerebellum | Cells in granular layer | Not detected | Protein (IHC) | HPA → |
| Cerebral cortex | Endothelial cells | Not detected | Protein (IHC) | HPA → |
| Cervix | Glandular cells | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced MFSD1 IHC Tips
Troubleshoot MFSD1 chromogenic IHC in paraffin sections by checking retrieval, controls, cell identity and compartment before interpreting staining intensity.
How should I retrieve MFSD1 in paraffin sections when staining is weak?
Use citrate pH 6.0 heat-induced antigen retrieval at 95–98 °C for 20 min (page retrieval rule: cytoplasmic / membrane antigen). Compare a retrieval-treated section with an untreated section from the same block, keeping antibody concentration and chromogen development constant (standard IHC practice). MFSD1 has 12 transmembrane segments, so assess whether improved staining has a plausible cellular distribution rather than assuming every darker signal is specific (UniProt Q9H3U5 topology). If staining remains weak, vary heating duration in a small controlled series before trying a different buffer or pH (standard IHC practice). Include a known positive cell population in each run to distinguish retrieval failure from a genuinely low signal (HPA: High in tonsil germinal center cells; standard IHC practice).
Can fixation explain absent or patchy MFSD1 staining?
MFSD1-specific fixation sensitivity is unknown from the supplied evidence; the rat lung tissue-IHC caption reports 10 µg/mL antibody but does not state a fixative (catalog antibody A17695 caption). For paraffin IHC, compare sections fixed and processed under documented, consistent conditions before attributing weak staining to the antigen itself (standard IHC practice). Record fixation duration, block age, retrieval conditions and section thickness alongside the result so that a processing difference can be investigated (standard IHC practice). Use an internal positive cell population and a matched negative control to assess whether a patchy pattern follows tissue handling or cell identity (standard IHC practice; HPA: High in tonsil germinal center cells).
Which MFSD1 staining pattern should I accept in tissue?
Score cell-associated cytoplasmic staining in the relevant tissue population while recording any convincing membrane-associated pattern separately (HPA tissue IHC: cytoplasmic expression mainly in subsets of immune cells; HPA subcellular: approved plasma membrane and cytosol). MFSD1 is annotated as a lysosome membrane protein, so a punctate intracellular pattern is biologically plausible, although chromogenic IHC alone cannot establish lysosomal residence (UniProt Q9H3U5 subcellular location; standard IHC interpretation). Overexpression can also produce Golgi detection and should not be used as the sole template for native tissue staining (UniProt Q9H3U5 subcellular note). Compare stained and unstained cells within the same section, and check morphology before assigning a diffuse signal to MFSD1 (standard IHC practice).
Could isoforms or epitope access change MFSD1 IHC results?
MFSD1 has 6 annotated isoforms and 12 transmembrane segments, making antibody epitope location important when interpreting a negative paraffin section (UniProt Q9H3U5 isoforms and topology). The supplied evidence does not identify this antibody’s epitope or establish which isoforms it detects (catalog antibody A17695 caption; UniProt Q9H3U5 isoforms). Check the antibody’s documented immunogen region before claiming coverage of a particular isoform, and use a second validated epitope or an orthogonal expression measure if isoform coverage matters (standard IHC validation practice). Keep retrieval and detection settings matched when comparing antibodies, since unequal processing can mimic an epitope-dependent difference (standard IHC practice).
How can IF help check an ambiguous MFSD1 IHC pattern?
On an adjacent section, multiplex MFSD1 IF with a marker identifying the cell population implicated by the IHC result, such as a macrophage marker when assessing lung macrophages (HPA: Low in lung macrophages; standard IF practice). Select spectrally separated fluorophores and place the weaker target signal in a channel with lower tissue autofluorescence, checking single-stain and unstained controls (standard IF practice). Choose permeabilisation after establishing whether the antibody epitope faces the cytosol or lysosomal lumen; MFSD1 spans the membrane 12 times, but the supplied evidence does not map this antibody’s epitope (UniProt Q9H3U5 topology; standard IF practice). Treat IF colocalisation as supporting evidence and return to cell morphology and negative controls when scoring chromogenic IHC (standard IHC/IF interpretation).
How do I reduce diffuse or misleading MFSD1 chromogenic background?
First inspect a no-primary control to separate antibody-dependent staining from detection-system or tissue background (standard IHC practice). For peroxidase-based chromogenic IHC, include a peroxidase block before DAB development and compare sections processed with identical development times; these are general workflow controls, not MFSD1-specific conditions (standard IHC practice). If the signal is diffuse, titrate the primary antibody and strengthen appropriate protein blocking while preserving a positive reference population (standard IHC practice; HPA: High in tonsil germinal center cells). Review section edges, damaged areas and pigmented material separately from intact cells, since their color can inflate an apparent MFSD1-positive area (standard IHC interpretation).
What should I measure when comparing MFSD1 staining across sections? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and tissue region before scoring, then report the percentage of positive cells and an intensity-weighted H-score using the same thresholds across slides (standard IHC quantification practice). Where immune cells are sparse, report positive-cell density per mm² of evaluable tissue or the fraction of the identified cell population that stains, rather than whole-section brown area alone (standard IHC quantification practice; HPA tissue IHC: subsets of immune cells). Normalise to the number of eligible cells or evaluable tissue area, and exclude necrotic and edge-damaged regions using prespecified rules (standard IHC quantification practice). Keep retrieval, counterstain, imaging and chromogen development consistent across comparison groups (standard IHC practice).
When should an apparent MFSD1-positive result be questioned?
Question staining confined to tissue edges, necrotic zones or the no-primary control before interpreting it as MFSD1 expression (standard IHC interpretation). Check whether positive cells match the expected tissue context: HPA reports cytoplasmic expression mainly in immune-cell subsets, including Low staining in lung macrophages and High staining in tonsil germinal center cells (HPA tissue IHC). A purely nuclear signal requires particular scrutiny because MFSD1 is annotated at the lysosome membrane, while HPA subcellular data also report plasma-membrane and cytosolic locations (UniProt Q9H3U5 subcellular location; HPA subcellular). Finally, rule out endogenous peroxidase and confirm that signal follows intact cell morphology rather than nonspecific DAB deposition (standard IHC practice).
Boster reagents
Best MFSD1 / Lysosomal dipeptide transporter MFSD1 IHC Antibodies
A17695 has a rat lung IHC image; its catalog lists human, mouse, and rat reactivity (image caption; catalog reactivity). No IF image is provided (catalog IF image alts).
Real IHC data
Anti-MFSD1 Antibody
Cat # A17695
A17695 is listed for IHC-P, with a rat lung IHC image at 10 μg/mL (catalog applications; image caption). Human, mouse, and rat reactivity are listed, while the pictured IHC result is from rat tissue (catalog reactivity; image caption).
Which to pick: Choose A17695 for paraffin-section tissue IHC: IHC-P is listed, and its own image caption shows rat lung IHC at 10 μg/mL; the fixative is unreported (catalog applications; image caption). No listed SKU has IF/ICC in its applications or an IF image, so the catalog does not support an IF/ICC recommendation (catalog applications; IF image alts). For cross-species IHC, A17695 lists human, mouse, and rat reactivity, though pictured IHC evidence covers rat lung only; clonality is unreported (catalog reactivity; image caption; clone field).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry Q9H3U5 (MFSD1_HUMAN, Lysosomal dipeptide transporter MFSD1).
- Human Protein Atlas. MFSD1 tissue IHC expression (reliability: Approved).
- Human Protein Atlas. MFSD1 subcellular location (ICC-IF): Mainly localized to the plasma membrane. In addition localized to the cytosol..
- Human Protein Atlas. MFSD1 antibody validation summary (1 antibodies).
- The Novel Membrane-Bound Proteins MFSD1 and MFSD3 are Putative SLC Transporters Affected by Altered Nutrient Intake. Journal of molecular neuroscience : MN 2017 — PMC5321710.
- PubMed PMID:14702039 — UniProt-cited evidence.
- PubMed PMID:15489334 — UniProt-cited evidence.
- PubMed PMID:30910009 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for MFSD1 (Lysosomal dipeptide transporter MFSD1). Expected localisation Cytoplasmic staining in immune-cell subsets (HPA tissue IHC). Antigen retrieval: Citrate pH 6.0 HIER, 95–98 °C, 20 min (rule: cytoplasmic / membrane antigen). Validated IHC antibody: A17695 at 10 μg/mL (the product's own IHC validation image is shown). Controls (HPA): positive Appendix (Lymphoid tissue); negative Adipose tissue. IHC workflow; specimen preparation unspecified. Protocol steps: 1. Sample: Tissue sections; selected-image fixative not specified (standard IHC workflow); 2. Fixation: Image fixative and duration unreported (datasheet A17695); verify before use.; 3. Sectioning: 4–5 µm sections on charged slides (standard); 4. Deparaffinisation: Xylene, graded ethanol series to water (standard); 5. Antigen retrieval: Heat-induced epitope retrieval in citrate buffer, pH 6.0 , 20 min at 95–98 °C…; 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% normal serum of the secondary host, 30 min , room temperature (standard); 8. Primary antibody: Rabbit anti-MFSD1, 10 μg/mL (datasheet A17695); 9. Primary incubation: Overnight at 4 °C (standard). Watch for: Fixation: Keep fixation consistent across sections (standard IHC practice; not target-specific); Caveat: Catalog antibody IHC validated in rat, not human (datasheet); Isoform / epitope: 6 isoforms (UniProt); epitope unmapped (datasheet); Regulation: No expression regulator annotated (UniProt). Evidence: UniProt Q9H3U5, HPA tissue IHC · Approved, HPA ICC-IF · Mainly localized to the plasma membrane. In addition localized to…, Datasheet A17695, PMC5321710. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/MFSD1/immunohistochemistry-ihc-guide.