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SIK1 / Serine/threonine-protein kinase SIK1 · IHC design guide
Design Immunohistochemistry for SIK1
Plan chromogenic SIK1 IHC in paraffin sections using the catalog antibody validated for human IHC-P at 5 μg/mL (datasheet: A04399). Assess nuclear and cytoplasmic staining (HPA tissue IHC), and verify specificity because staining and RNA show low consistency (HPA tissue IHC).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
SIK1 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 | Nuclear and cytoplasmic staining (HPA tissue IHC) | |
| Staining pattern | Glandular cells show high nuclear and cytoplasmic staining (HPA tissue IHC) | |
| Antigen retrieval | Tris-EDTA pH 9.0 HIER, 95–98 °C, 20 min (rule: nuclear antigen) | |
| Positive control | Adrenal gland+4 more · see all | |
| Negative control | None in HPA (detected in all 45 tissues); use no-primary + isotype controls |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Keep fixation conditions consistent across samples. (standard IHC practice; not target-specific) | |
| Caveat | Staining and RNA show low consistency; verify specificity (HPA tissue IHC) | |
| Regulation | cAMP may shift SIK1 to the cytoplasm (UniProt) | |
| Isoform / epitope | No annotated isoforms; one 1–783 chain (UniProt) |
Section 1
Recommended SIK1 IHC & IF Protocols
The catalog antibody’s IHC-P protocol is accompanied by published SIK1 chromogenic IHC protocols for kidney, liver, brain and lymphoma specimens (PMC7885408; PMC6590778; PMC10726907; PMC5746112).
| Sample | Tissue sections; selected-image fixative not specified (standard IHC workflow) |
| Fixation | Image fixative and duration unreported (datasheet A04399); 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 Tris-EDTA buffer, pH 9.0, 20 min at 95–98 °C (standard rule: nuclear 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-SIK1, 5 μg/mL (datasheet A04399) |
| 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 | SIK1-positive staining in glandular cells of adrenal gland (HPA tissue IHC: High). HPA tissue profile: General nuclear and cytoplasmic expression. No signal in the no-primary control. |
💡Decision noteFor paraffin sections, start with Tris-EDTA pH 9.0 retrieval at 95–98 °C for 20 min (page antigen-retrieval rule; UniProt: nuclear localisation).
Section 2
What Is the Expected SIK1 Staining Pattern?
SIK1 can localize to the nucleus and cytoplasm (UniProt P57059). In tissue IHC, expect nuclear and cytoplasmic staining in the cell types reported by HPA, including adrenal glandular cells, bronchial respiratory epithelial cells and cerebral cortex glial cells (HPA: High). SIK1 has no transmembrane segment (UniProt P57059 topology). Treat this pattern as a guide: HPA rates the tissue IHC evidence Approved but reports low consistency with RNA expression and pending external verification (HPA: tissue IHC reliability).
| Clear nuclear staining, with or without cytoplasmic staining, in adrenal glandular cells or bronchial respiratory epithelial cells. | This fits SIK1's nuclear and cytoplasmic localization (UniProt P57059) and the reported High staining in those cell types (HPA: tissue IHC). Compare the signal with neighboring cells and the negative reagent control before scoring it as specific (general IHC practice). |
| Signal is restricted to cell borders or an extracellular deposit, with no convincing intracellular staining. | A border-only or extracellular pattern warrants investigation: SIK1 is reported in the nucleus and cytoplasm and has no transmembrane segment or signal peptide (UniProt P57059). Inspect morphology and control slides for an artefact; the supplied sources do not validate a surface or extracellular IHC pattern. |
| Strong staining appears chiefly in a cell population other than the one expected for the selected tissue. | Recheck cell identity before calling it SIK1. For example, the High bronchus entry refers to respiratory epithelial cells (HPA: tissue IHC). A discordant pattern may reflect antibody cross-reactivity or endogenous detection activity (general IHC practice); HPA lists low tissue specificity, so an unlisted cell type alone cannot establish a false positive (HPA: RNA specificity). |
| Brown chromogen is spread across the section without distinct cellular boundaries or interpretable nuclei. | Diffuse staining is difficult to score as SIK1 even where expression is reported. Check reagent and tissue controls for nonspecific binding or endogenous detection activity, then assess whether localization becomes interpretable (general chromogenic IHC practice). HPA's nuclear and cytoplasmic tissue profile does not validate uniform background (HPA: tissue IHC profile). |
| No signal is visible in an adrenal gland section's glandular cells under the selected staining conditions. | Those cells are a reasonable positive tissue check because HPA reports High staining there (HPA: adrenal gland IHC). Review section integrity, retrieval, antibody working conditions and detection controls (general IHC practice). An absent result does not by itself prove that the specimen lacks SIK1, particularly given HPA's reported RNA–staining inconsistency (HPA: tissue IHC reliability). |
💡Expected SIK1 appearanceCall a result consistent with SIK1 when distinct nuclear and/or cytoplasmic signal is visible in an HPA-reported High cell population, such as adrenal glandular cells (UniProt P57059 localization; HPA: tissue IHC); isolated border staining or diffuse chromogen without cellular detail is suspect (UniProt P57059 topology; general IHC practice).
| Compartment and signaling state | UniProt places SIK1 in the nucleus and cytoplasm and notes cytoplasmic localization when inactive after cAMP-induced phosphorylation, probably by PKA (UniProt P57059). Nuclear-only and mixed intracellular patterns therefore need context; a fixed tissue section cannot establish kinase activity from compartment alone. |
| Tissue evidence and antibody agreement | HPA lists High staining in several cell populations, but rates tissue IHC Approved with low consistency between antibody staining and RNA expression and pending external verification (HPA: tissue IHC). HPA lists IHC as Approved for HPA038211 and CAB023801; the supplied record does not give an IHC Enhanced designation (HPA: antibody validation). |
| Intracellular protein architecture | SIK1 has a kinase domain at residues 27–278, a UBA domain at 303–343, no transmembrane segment and no annotated signal peptide or propeptide (UniProt P57059). These facts support checking intracellular localization; they do not identify the catalog antibody's epitope or predict its staining intensity. |
| Phosphorylation | UniProt lists phosphorylation sites including Thr-473 and Ser-575 and describes phosphorylation-dependent interaction with 14-3-3 proteins (UniProt P57059). The supplied evidence does not show whether these modifications alter recognition by the IHC antibody; do not infer a staining change from phosphorylation alone. |
| Antigen retrieval and detection | Optimize retrieval and chromogenic detection against positive tissue and reagent controls (general IHC practice). No target-specific retrieval condition, fixation sensitivity or IHC dilution is supplied, so a particular treatment cannot be presented as established for SIK1. |
| IF/ICC: where should signal appear? | HPA reports mainly nucleoplasmic signal and additional vesicle localization in ICC-IF, with Approved location annotations (HPA: subcellular). This informs an IF localization check; it is separate from the tissue IHC pattern and supplies no IF protocol. |
| Situation | Likely cause | Next action |
|---|---|---|
| Expected positive tissue is blank. | The run may have lost detectable signal through a section, retrieval, primary antibody or detection problem (general IHC practice); one blank slide cannot establish absent SIK1. | Repeat with a documented positive tissue cell population, such as adrenal glandular cells (HPA: High), and check the section, retrieval and detection controls in sequence (general IHC practice). |
| Every area, including morphologically negative spaces, looks brown. | Broad background can arise from nonspecific binding, excess reagent or endogenous detection activity (general chromogenic IHC practice). | Examine a primary-antibody-omission control; then adjust blocking, reagent concentration or washing as indicated by the control result (general IHC practice). Score SIK1 only where cells and compartments remain discernible. |
| Signal is confined to membranes or extracellular material. | This distribution conflicts with the reported nuclear and cytoplasmic localization and lack of a transmembrane segment or signal peptide (UniProt P57059). | Verify that the signal tracks intact cells, inspect reagent controls and compare a reported positive tissue (general IHC practice; HPA: tissue IHC). Do not score a border-only deposit as a supported SIK1 pattern. |
| Unexpected cells stain more strongly than the HPA-listed cells. | Cell identification, cross-reactivity or endogenous chromogenic activity may explain the contrast (general IHC practice); HPA's low tissue specificity prevents treating every unlisted cell as negative (HPA: RNA specificity). | Reidentify the stained cells on the counterstained section and compare controls and an HPA-listed cell population before interpreting the contrast (general IHC practice; HPA: tissue IHC). |
| A run shows cytoplasmic signal but little nuclear signal. | Cytoplasmic localization is compatible with the UniProt record, including its note about inactive SIK1 after cAMP-induced phosphorylation (UniProt P57059); staining alone cannot identify that signaling state. | Check that cytoplasmic staining is cell-defined and control-dependent, then report the observed compartment without assigning kinase activity (general IHC practice; UniProt P57059 localization). |
| The tissue IHC pattern differs from an ICC-IF image. | HPA reports general nuclear and cytoplasmic tissue staining but mainly nucleoplasmic and additional vesicle localization in ICC-IF (HPA: tissue IHC; HPA: subcellular). The assays provide different observations. | Interpret each preparation against its own controls and reported compartment pattern (general IHC/IF practice). For this paraffin IHC section, prioritize cellular tissue morphology and the HPA tissue IHC evidence. |
Experiment evidence
IHC & IF images showing SIK1 staining
A04399 · IHCImmunohistochemistry of SIK1 in human small intestine tissue with SIK1 antibody at 5 μg/mL.
A04399-2 · IFIF analysis of SIK1 using anti-SIK1 antibody (A04399-2) and anti-Beta Tubulin antibody (M01857-3). SIK1 was detected in an immunocytochemica
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000142178-SIK1/tissue/cerebral+cortex#imid_6168168
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000142178-SIK1/tissue/colon#imid_6168094
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000142178-SIK1/tissue/liver#imid_6168111
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000142178-SIK1/tissue/kidney#imid_6168104
HPA · ICC-IF A-549Human Protein Atlas immunofluorescence, A-549, antibody HPA078064; green = SIK1, blue = nucleus, red = microtubules.
HPA · ICC-IF A-549Human Protein Atlas immunofluorescence, A-549, antibody HPA078064; green = SIK1, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for SIK1 IHC & IF
🧪Run adrenal gland first: glandular cells should stain (HPA: High in adrenal gland glandular cells). HPA detects SIK1 in all 45 scored tissues, so use no-primary and isotype controls for the negative comparison; assess non-glandular cells for background without assuming they are SIK1-negative (HPA: no negative tissue rows).
Positive control tissue: Adrenal gland (Glandular cells, HPA High)
Negative control tissue: None in HPA: SIK1 is detected in all 45 scored tissues. Use a no-primary (secondary-only) and an isotype control instead.
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show SIK1 in A-549, SiHa, U2OS, with annotated localisation: Nucleoplasm (approved) (HPA subcellular).
Technical controls: Include a secondary-only slide, an isotype control matched to the primary antibody’s host species, clonality and concentration, and a matched SIK1 knockout sample if available (standard IHC controls). For chromogenic detection in adrenal gland, block endogenous peroxidase and check for intrinsic pigment; block endogenous biotin if using avidin–biotin detection (standard IHC practice).
⚠️Feasibility: No SIK1-specific fixation window or fixation effect is reported in the supplied evidence; the A04399 small-intestine IHC caption reports 5 μg/mL but leaves the fixative unreported (selected tissue-IHC caption). Antigen-retrieval dependence is unreported, so optimize retrieval on paraffin sections (standard IHC practice). The evidence does not establish whether frozen sections or IF are easier; for IF, the HPA reference pattern is mainly nucleoplasmic with additional vesicular staining, and intrinsic tissue pigment should be checked when interpreting adrenal chromogenic staining (HPA subcellular; standard IHC practice).
HPA tissue IHC evidence for SIK1
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Approved — Low consistency between antibody staining and RNA expression data. Pending external verification.). 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 |
|---|---|---|---|---|
| Adrenal gland | Glandular cells | High | Protein (IHC) | HPA → |
| Appendix | Glandular cells | High | Protein (IHC) | HPA → |
| Bone marrow | Hematopoietic cells | High | Protein (IHC) | HPA → |
| Breast | Glandular cells | High | Protein (IHC) | HPA → |
| Bronchus | Respiratory epithelial cells | High | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| None in HPA: SIK1 is detected in all 45 scored tissues. Use a no-primary (secondary-only) and an isotype control instead. | ||||
Section 3
Advanced SIK1 IHC Tips
Troubleshoot SIK1 staining in paraffin sections by checking retrieval, compartment, cell identity, and control tissue before comparing signal intensity (UniProt P57059; HPA tissue IHC).
What should I change if SIK1 staining is weak after antigen retrieval?
Use Tris-EDTA at pH 9.0 for heat-induced retrieval at 95–98 °C for 20 min in paraffin sections (page retrieval setting). Let slides cool in retrieval buffer, then compare the same tissue and antibody dilution across retrieval runs (standard IHC practice). Include a section from the documented small intestine staining example at 5 µg/mL as a reference, while recognizing that its fixative was unreported (caption A04399). If signal remains weak, check reagent activity and section adhesion before changing retrieval conditions (standard IHC practice). Score nuclear and cytoplasmic staining separately because both compartments are reported for SIK1 (UniProt P57059; HPA tissue IHC).
Could fixation explain weak or uneven SIK1 staining?
Target-specific sensitivity of SIK1 to fixation is unknown from the supplied evidence; the selected tissue-IHC caption does not state a fixative (caption A04399). Record fixative, time in fixative, section age, and processing history for each specimen before comparing staining intensity (standard IHC practice). Run sections processed together through the same retrieval and detection sequence, using a known staining reference alongside them (standard IHC practice). If staining varies with processing history, treat fixation as a possible technical variable rather than a demonstrated SIK1-specific effect (standard IHC practice). Do not infer fixation tolerance from tissue staining patterns or predicted protein features (HPA tissue IHC; UniProt P57059).
How should I assess nuclear versus cytoplasmic SIK1 staining?
Assess nuclear and cytoplasmic staining independently because both are reported for SIK1 in tissue (HPA tissue IHC; UniProt P57059). Use a nuclear counterstain and inspect intact cells at high magnification before assigning chromogenic signal to either compartment (standard IHC practice). SIK1 can move to the cytoplasm when inactive after cAMP-induced phosphorylation, probably by PKA, so compartment shifts need biological context (UniProt P57059). Nuclear signal also fits the approved nucleoplasmic localisation reported by cell imaging, while vesicular signal is an additional reported location (HPA subcellular). Compare matched regions and controls before interpreting a compartment shift as altered kinase activity (standard IHC practice; UniProt P57059).
Could the antibody epitope or SIK1 modifications affect staining?
The supplied SIK1 record lists 0 isoforms, so it provides no annotated isoform explanation for differing staining patterns (UniProt P57059). Its kinase domain spans residues 27–278 and its UBA domain spans 303–343, but the catalog antibody’s epitope is not supplied (UniProt P57059; supplied antibody evidence). Document the antibody clone or catalog identifier and seek its mapped epitope before assigning a weak region to epitope loss (standard IHC practice). SIK1 has reported phosphorylation sites including Thr-182, Thr-473, and Ser-575; their presence alone does not establish antibody sensitivity to phosphorylation (UniProt P57059). Compare matched processing and appropriate specificity controls before interpreting staining differences as molecular variants (standard IHC practice).
How can I check SIK1 localisation with multiplex immunofluorescence?
For a separate IF/ICC experiment, pair SIK1 with a marker identifying the cell population under study and include a nuclear stain to distinguish compartments (standard IF practice). In glandular tissue, an epithelial marker can help identify the cells to compare with reported glandular staining (HPA tissue IHC; standard IF practice). Choose spectrally separated fluorophores and assign the cleaner, brighter channel to the weaker signal after checking tissue autofluorescence (standard IF practice). Permeabilise cells for intracellular SIK1 epitopes, since SIK1 is reported in cytoplasm and nucleus and has no transmembrane segment (UniProt P57059; standard IF practice). Set IF/ICC fixation and antibody conditions using direct IF/ICC evidence or controls, without transferring the tissue-IHC caption’s conditions (caption A04399; standard IF practice).
What should I check when chromogenic SIK1 staining is diffuse?
Compare stained sections with a primary-antibody omission control and inspect whether diffuse color follows tissue edges or damaged areas (standard IHC practice). Confirm that the peroxidase block and washes are effective before changing antibody concentration or increasing blocking time (standard IHC practice). Review antibody concentration against the documented small intestine image at 5 µg/mL, recognizing that the caption gives no processing details (caption A04399). Genuine SIK1 signal may occupy nuclei and cytoplasm, so diffuse color alone is insufficient to classify a slide as background (UniProt P57059; HPA tissue IHC). Repeat the comparison in intact cells with a consistent counterstain and exposure to chromogen (standard IHC practice).
How should I quantify SIK1 staining across paraffin sections? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and anatomical region before scoring, then keep section thickness, staining run, and image settings consistent (standard IHC practice). Record nuclear and cytoplasmic results separately because both locations are reported for SIK1 (UniProt P57059; HPA tissue IHC). For cell-based staining, report percent positive cells and an H-score combining intensity with the fraction of cells at each intensity (standard IHC practice). If counting spatially, report positive-cell density per mm² of viable, evaluable tissue and state the segmentation rules (standard IHC practice). Normalize comparisons to the same eligible cell population or viable tissue area, and include a shared reference section across runs (standard IHC practice).
How can I distinguish true SIK1 staining from artefact?
Treat staining in intact nuclei or cytoplasm as plausible for SIK1, but verify cell boundaries and the nuclear counterstain (UniProt P57059; HPA tissue IHC; standard IHC practice). Strong staining in an unexpected cell population needs comparison with a matched control and morphology before it is assigned to SIK1 (standard IHC practice). Discount signal concentrated at section edges, folds, or necrotic areas, and check a primary-antibody omission control for endogenous enzyme or detection background (standard IHC practice). Report the observed compartment and cell type rather than inferring kinase activation from chromogenic intensity alone (UniProt P57059; standard IHC practice). Interpret tissue patterns cautiously because the HPA tissue-IHC reliability note reports low agreement with RNA expression (HPA tissue IHC).
Boster reagents
Best SIK1 / Serine/threonine-protein kinase SIK1 IHC Antibodies
Anti-SIK1 antibodies have human small intestine IHC data (A04399 image caption) and human HeLa IF/ICC data (A04399-2 image caption); listed reactivity also includes mouse and rat (catalog: A04399-2 reactivity).
Real IHC data
Anti-SIK1 Antibody
Cat # A04399
Real IF data
Anti-Snf1lk/SIK1 Antibody ®
Cat # A04399-2
A04399 is listed for human IHC-P and shown staining human small intestine tissue at 5 μg/mL (catalog: A04399 applications/reactivity; A04399 IHC image caption). A04399-2 is listed for IF/ICC and shown in human HeLa cells at 5 μg/mL (catalog: A04399-2 applications; A04399-2 IF image caption).
Which to pick: Choose A04399 for human paraffin-section IHC (catalog: A04399 IHC-P application and human reactivity); its tissue caption does not report the fixative (A04399 IHC image caption). Choose A04399-2 for human IF/ICC (catalog: A04399-2 applications; A04399-2 IF image caption), or when mouse or rat reactivity is needed (catalog: A04399-2 reactivity); the supplied IF image documents human cells only (A04399-2 IF image caption). Neither catalog entry reports a clone (catalog: A04399 and A04399-2 clone fields).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry P57059 (SIK1_HUMAN, Serine/threonine-protein kinase SIK1).
- Human Protein Atlas. SIK1 tissue IHC expression (reliability: Approved).
- Human Protein Atlas. SIK1 subcellular location (ICC-IF): Mainly localized to the nucleoplasm. In addition localized to vesicles..
- Human Protein Atlas. SIK1 antibody validation summary (3 antibodies).
- Role of SIK1 in the transition of acute kidney injury into chronic kidney disease. Journal of translational medicine 2021 — PMC7885408.
- Adenovirus-mediated expression of SIK1 improves hepatic glucose and lipid metabolism in type 2 diabetes mellitus rats. PloS one 2019 — PMC6590778.
- Blocking salt-inducible kinases with YKL-06-061 prevents PTZ-induced seizures in mice. Brain and behavior 2023 — PMC10726907.
- Clinical impact of miR-223 expression in pediatric T-Cell lymphoblastic lymphoma. Oncotarget 2017 — PMC5746112.
- PubMed PMID:14976552 — UniProt-cited evidence.
- PubMed PMID:10830953 — UniProt-cited evidence.
- PubMed PMID:15489334 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for SIK1 (Serine/threonine-protein kinase SIK1). Expected localisation Nuclear and cytoplasmic staining (HPA tissue IHC). Antigen retrieval: Tris-EDTA pH 9.0 HIER, 95–98 °C, 20 min (rule: nuclear antigen). Validated IHC antibody: A04399 at 5 μg/mL (the product's own IHC validation image is shown). Controls (HPA): positive Adrenal gland (Glandular cells); negative None in HPA (detected in all 45 tissues); use no-primary + isotype controls. 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 A04399); 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 Tris-EDTA buffer, pH 9.0 , 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-SIK1, 5 μg/mL (datasheet A04399); 9. Primary incubation: Overnight at 4 °C (standard). Watch for: Fixation: Keep fixation conditions consistent across samples. (standard IHC practice; not target-specific); Caveat: Staining and RNA show low consistency; verify specificity (HPA tissue IHC); Isoform / epitope: No annotated isoforms; one 1–783 chain (UniProt); Regulation: cAMP may shift SIK1 to the cytoplasm (UniProt). Evidence: UniProt P57059, HPA tissue IHC · Approved, HPA ICC-IF · Mainly localized to the nucleoplasm. In addition localized to…, Datasheet A04399, PMC7885408, PMC6590778. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/SIK1/immunohistochemistry-ihc-guide.