Other · Scorpion α-KTx voltage-gated potassium-channel blocker
Margatoxin
Also known as MgTx; α-KTx 2.2
A 39-residue scorpion toxin that blocks several Kv1 channels and requires selectivity controls in Kv1.3-focused experiments.
- Length
- 39 amino acids
- Half-life
- Not well characterised
- Mechanism
- Margatoxin binds the extracellular vestibule of susceptible Kv1 channels and blocks potassium permeation through the pore. It inhibits Kv1.3 and Kv1.2 with high affinity and can also inhibit Kv1.1, so it is not a Kv1.3-specific probe.
- Studied in
- Recombinant expression systems, lymphocyte electrophysiology and neuronal preparations use margatoxin to examine Kv1-dependent currents and their relationship to cellular signalling.
About Margatoxin
Margatoxin is a 39-amino-acid peptide isolated from the venom of the scorpion Centruroides margaritatus and described in the early 1990s. Three disulphide bonds stabilise its cysteine-stabilised α/β fold, a common structural framework among short scorpion potassium-channel toxins. Its historical designation as α-KTx 2.2 places it within a sequence-based toxin classification. The rigid scaffold presents a channel-binding surface that interacts with the external vestibule of susceptible voltage-gated potassium channels in experimental preparations.
Although frequently described as a Kv1.3 blocker, margatoxin also potently inhibits Kv1.2, with additional activity at Kv1.1 under appropriate assay conditions. This overlapping pharmacology is central to interpreting experiments in cells expressing several Kv1 subunits. Native channels may also be heteromeric, making results from single-subunit expression systems an incomplete guide to complex tissues. Robust attribution therefore combines margatoxin responses with channel-expression data, genetic perturbation or a panel of independently characterised pharmacological probes.
Laboratory notes
- Assess Kv1.2 and Kv1.1 alongside Kv1.3 when experimental conclusions depend on subtype specificity.
- Use a defined equilibration period and record washout behaviour; high-affinity binding can complicate sequential recordings.
- For research use only. Verify peptide folding and purity, and handle as a potent ion-channel toxin using the relevant safety data sheet.
Storage and reconstitution basics: storage guide.
Questions about Margatoxin
Is margatoxin selective for Kv1.3?
No. Its strong activity at Kv1.2 and activity at Kv1.1 mean that inhibition alone cannot establish a Kv1.3-mediated current.
What does α-KTx 2.2 mean?
It is a systematic scorpion potassium-channel toxin designation based on sequence relationships, rather than a statement of exclusive channel selectivity.
Why can native-cell results differ from recombinant-channel results?
Native cells can express multiple channel types and heteromeric Kv1 assemblies, changing both toxin sensitivity and the fraction of total current inhibited.
Is Margatoxin for human use?
No. It is supplied strictly for in-vitro laboratory research and is not for human or animal consumption.
Related research peptides
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