Kaliotoxin-1

Kaliotoxin-1 has been isolated from the venom of the Scorpion Androctonus mauretanicus mauretanicus. Kaliotoxin-1 is a potent inhibitor of large conductance calcium-activated potassium channels (BK-Ca). This toxin also binds to the dendrotoxin sensitive voltage-dependent potassium channel. It appears to block channel activity by a simple bimolecular inhibition process. Kaliotoxin-1 induces a transient period of fast flickering in the channel openings, followed by an almost complete blockade of the channel. Its binding affinity to rat brain synaptosomes is 5-fold higher than this of KTX-3. Binding of the toxin to the channel is associated with significant structural rearrangments in both molecules.