| Field | Specification |
|---|---|
| Mfr No | |
| Accession Number | |
| Activity | |
| Alternative Names | Kappa-stichotoxin-She3a, Potassium channel toxin ShK, Kappa-SHTX-She3a |
| Cas No. | |
| Concentration | |
| Form | Lyophilized |
| Formulation | |
| Gene ID | |
| Molecular Weight | |
| Product Type | |
| Purity | |
| Reconstitution | |
| Solubility | Centrifuge the vial before adding solvent (10,000 x g for 5 minutes) to spin down all the powder to the bottom of the vial. The lyophilized product may be difficult to visualize. Add solvent directly to the centrifuged vial. Tap the vial to aid in dissolving the lyophilized product. Tilt and gently roll the liquid over the walls of the vial. Avoid vigorous vortexing. Light vortexing for up to 3 seconds is acceptable if needed. The product is soluble in pure water at high micromolar concentrations (100 µM - 1 mM). For long-term storage in solution, we recommend preparing a stock solution by dissolving the product in double-distilled water (ddH2O) at a concentration between 100-1000x of the final working concentration. Divide the stock solution into small aliquots and store at -20°C. Before use, thaw the relevant vial(s) and dilute to the desired working concentration in your working buffer. Centrifuge all product preparations before use. It is recommended to prepare fresh solutions in working buffers just before use. Avoid multiple freeze-thaw cycles to maintain biological activity. |
| Source | Synthetic peptide |
| Species | |
| Storage | |
| Target |
Overview
ShK (Stichodactyla Toxin) is a research-grade protein/peptide reagent used in research settings. It is commonly applied as a tool reagent related to Various KV K+ channels biology and/or assay development. It is supplied in Lyophilized format to support flexible downstream use in RUO workflows. Researchers commonly pair it with applications such as Electrophysiology.
Key elements and design rationale
- Molecular identity: CAS: 172450-46-3, MW: 4054.8 Da, Formula: C169H274N54O48S7.
- Source / origin: Stichodactyla helianthus (Sun anemone) (Stoichactis helianthus).
- Quality attributes: Purity: ≥98% (HPLC); Bioassay tested: Yes; Sterile / endotoxin-free: No.
Modifications
Disulfide bonds between: Cys3-Cys35, Cys12-Cys28, and Cys17-Cys32
When used as a biochemical or pharmacological tool, results are best interpreted relative to the experimental system (species, expression level, and assay readout) and with appropriate negative and competition-style controls where relevant. This product is intended for research use only.
Biological background
ShK (Stichodactyla Toxin) is a peptidyl toxin originally isolated from the nematocyst of the sea anemone Stichodactyla helianthus.1ShK blocks KV1.3, KV1.1, KV1.4, and KV1.6 at subnanomolar concentrations and KV3.2 channels at 1000-fold higher concentration than that required to inhibit KV1.3 channels. It has been shown to block KV current in DRG neurons, to displace radioactive Dendrotoxin from brain synaptosomes1 and inhibit I125-Charybdotoxin binding to Jurkat T lymphocytes with an IC50 of 32 pM2,4Evidence also suggests that native KV currents in the central nervous system, which are predominantly carried by KV1.2 channels, are highly sensitive to this toxin.5A fluorescently labeled synthetic ShK is used to recognize and to sort KV1.3 containing lymphocytes.4,6
Research relevance and current trends
- Using high-specificity ligands, toxins, and engineered peptides to dissect closely related receptor/channel subtypes and signaling microdomains.
- Pairing labeled (e.g., fluorescent) proteins/peptides with advanced imaging to map surface expression, trafficking, and nanoscale organization.
- Increasing emphasis on reproducibility through standardized characterization (identity, purity, and lot QC) and transparent reporting of reagent attributes.
Common research applications
- Electrophysiology: commonly used to compare signal, binding, or functional readouts across conditions without implying a specific protocol.
Across these use cases, changes in signal or functional readout are generally interpreted as evidence of differences in target abundance, accessibility, or engagement, but alternative explanations (matrix effects, off-target interactions, or assay artifacts) should be considered.
Notes for experimental interpretation
- Assay context matters: binding assays, functional modulation, and detection workflows can yield different readouts even for the same target system.
- Target complexity: closely related family members, splice variants, and post-translational modifications can influence apparent specificity and potency.
- Matrix and sample effects: buffer composition, detergents, and biological matrices may alter stability or apparent activity; interpret with appropriate controls.
- Control concepts: include negative controls and orthogonal validation (e.g., genetic perturbation or alternative reagents) to support robust interpretation.
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Pennington, M. W
. et al. (2009) Mol. Pharmacol., 75, 762.
Castaneda, O.
et al. (1995) Toxicon33, 603.
Pennington, M. W.
et al. (1995) Int. J. Pept. Protein Res.46, 354.
Beeton, C.
et al. (2003) J. Biol. Chem. 278, 9928.
Middleton, R.E.
et al. (2003) Biochemistry42, 13698.
