a blocker of Ca²⁺-activated K⁺ channels of high conductance and some voltage-dependent K⁺ channels; in human and murin β-lymphocytes‚ where both K⁺ channels subtypes are present‚ Kaliotoxin is a selective voltage-dependent K⁺ channels blocker.

38-amino acid peptide with 3 disulfide bridges. ‚ synthetic‚ originally from Androctonus mauretanicus mauretanicus scorpion venom.

Neurons: KTX blocks the invertebrate and mammalian sympathetic high conductance K⁺ channels with a Kd of 2 to 4 nM. These effects were observed on the whole-cell current as well as on the unitary channel activity.

KTX inhibits the shaker K⁺ current resulting from mRNA expression in Xenopus oocyte with a Kd of 2 to 5 nM.

The radiolabelled derivative 125I KTX binds to the rat brain synaptosomal membrane (Kd = 10 pM) and it is displaced by Dendrotoxin with a Kd of 8 pM.



Muscle: KTX is poorly active on skeletal high conductance K⁺ channels incorporated in lipid bilayers.



Lymphocytes: in human and murin b-lymphocytes‚ where both Ca²⁺-activated K⁺ channels and voltage-dependent K⁺ channels are present‚ KTX selectively inhibits the activity of the voltage-dependent K⁺ channels with a Kd of 1 to 5 nM.

1. Crest et al., "Kaliotoxin, a novel peptidyl inhibitor of neuronal BK-type Ca²⁺-activated K⁺ channels characterized from Androctonus mauretanicus mauretanicus venom." J. Biol. Chem. (1992). 267(3):1640-1647