Other · Disulphide-rich potassium-channel toxin
Scyllatoxin
Also known as Leiurotoxin I; LTX I
A 31-residue scorpion toxin used to investigate apamin-sensitive KCa2 potassium channels and calcium-dependent excitability.
- Length
- 31 amino acids
- Half-life
- Not well characterised
- Mechanism
- Scyllatoxin binds extracellularly to susceptible small-conductance calcium-activated potassium channels, including KCa2.2/SK2, and inhibits potassium current. Its pharmacology overlaps with apamin-sensitive channels, although sensitivity depends on channel subtype and species.
- Studied in
- Recombinant channel assays, neuronal preparations and isolated tissue models use scyllatoxin to investigate calcium-dependent potassium currents and membrane excitability.
About Scyllatoxin
Scyllatoxin was isolated from the venom of the scorpion historically named Leiurus quinquestriatus hebraeus and is also known as leiurotoxin I. The mature peptide contains 31 amino acids and three intramolecular disulphide bonds. Its compact scaffold combines an alpha helix with a small beta sheet, characteristic of the cysteine-stabilised alpha/beta fold found in several scorpion toxins. Discovery and characterisation centred on its interaction with apamin-sensitive potassium-channel binding sites.
The principal targets are members of the KCa2, or SK, family of small-conductance calcium-activated potassium channels. These channels couple intracellular calcium signals to potassium efflux through constitutively associated calmodulin; scyllatoxin inhibits susceptible channels from the extracellular side rather than binding calmodulin. Electrophysiological studies use it to separate SK-dependent currents from other conductances. Because channel subtype, species and assay conditions influence sensitivity, a scyllatoxin-sensitive response alone does not establish a particular KCa2 subtype.
Laboratory notes
- Confirm peptide identity, purity and native disulphide connectivity; reduced or misfolded material may not reproduce reference pharmacology.
- Use low-binding labware and validated aliquoting conditions to minimise adsorption and repeated freeze–thaw cycles.
- Include subtype-defined channel controls and a complementary SK-channel probe when assigning current identity.
Storage and reconstitution basics: storage guide.
Questions about Scyllatoxin
Is scyllatoxin structurally related to apamin?
They are distinct peptides with different sequences and folds, but their pharmacology overlaps at susceptible KCa2 channels.
Does scyllatoxin inhibit every potassium channel activated by calcium?
No. Its established use concerns susceptible small-conductance KCa2 channels; it should not be treated as a general blocker of KCa1 or KCa3 channels.
Why does the disulphide pattern matter?
The three disulphide bonds stabilise the channel-binding conformation. Correct mass alone cannot demonstrate native folding.
Is Scyllatoxin for human use?
No. It is supplied strictly for in-vitro laboratory research and is not for human or animal consumption.
Related research peptides
All products are sold for laboratory research use only. Not for human consumption, not a medicine, not for diagnosing, treating or preventing any condition.