AmmTX3
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| Superfamily | Short scorpion toxins |
|---|---|
| Family | Scorpion toxins |
| Subfamily | α-KTX15 |
| Amino acid | ZIETNKKCQGGSCASVCRKVIGVAAGKCINGRCVCYP[1] |
| Molecular weight | 3823.5 Da |
AmmTX3, produced by Androctonus mauretanicus, is a scorpion toxin of the α-KTX15 subfamily. The toxin is known for its ability to act as a specific Kv4 channel blocker, and thereby reducing the A-type potassium current through this channel.
AmmTX3 (α-KTX15.3) is a peptide that can be isolated from the venom of Androctonus mauretanicus.[1] Androctonus mauretanicus is a fat-tailed scorpion with its origins in North Africa.
Chemistry
AmmTX3 has a molecular mass of 3823.5 Da and consists of a single chain of 37 amino acid residues. These residues are cross-linked by three disulfide bridges.[1] The toxin contains the dyad characteristic (K27 and Y36) that is found in pore-blocking potassium channel-specific toxins, and is therefore likely to act as a pore blocker.
AmmTX3 is a member of the α-KTX15 subfamily. This subfamily currently exists of six very homologous peptides, originating from scorpion venom: Aa1, AaTX1, AaTX2, AmmTX3, BmTx3 and Discrepin.[1][2] Toxins of the α-KTX15 subfamily all seem to have an effect on the A-type potassium current.
Target
AmmTX3 is a specific pore blocker of Kv4.2 and Kv4.3 channels of mice. This high-affinity blockade depends on the expression of dipeptidyl peptidase-like proteins (DPP) DPP6 and DPP10, which are proteins that co-assemble with the alpha-subunits of Kv4 channels.[2][3] Besides its potent ability to block Kv4 channel, AmmTx3 also has a small blocking effect on hERG channels without alteration of the gating kinetics.[4]