AmmTx3

AmmTx3 has been originally isolated from the venom of the scorpion Androctonus mauretanicus and is now offered bySmartox in its synthetic version. AmmTx3 binds on its target A-type potassium channel with an affinity of 66 pM in rat brain synaptosomes (K_v4 channels). As such, AmmTx3 should represent an excellent tool to study action potential firing frequency, spike initiation and waveform in excitable cells. AmmTx3 was indeed found to block A-type potassium currents from cerebellum granular cells and from striatum neurons but with IC₅₀ values of 130 nM. AmmTx3 appears to be a pore blocker of K_v4.2 and K_v4.3 and seems to require the expression of the K_v4 associated protein DPP6. It should also contribute to our understanding of learning, memory and behavior. AmmTx3 shares very high sequence homology with two other A-type potassium channel blockers, Aa1 from Androctonus australis (94%) and BmTx3 from Buthus martensi (91%), and according to binding experiments the same channel target as well. AmmTx3 is a member of the a-KTX 15 family of toxins and consist of a single chain of 37 amino acid residues, with an N-terminal pyroglutamate, cross-linked by three disulfide bridges.