iberiotoxin

Iberiotoxin is a peptide toxin derived from the venom of the Iberian scorpion Buthus ibericus. It is a potent, selective inhibitor of large-conductance calcium-activated potassium channels (BK channels), which are involved in regulating neuronal excitability and smooth muscle tone.

The toxin is a small, disulfide-rich peptide, typically composed of about 40 amino acids with multiple disulfide bonds that stabilize its structure. Iberiotoxin binds to the external vestibule of the BK channel’s alpha-subunit, acting as a pore blocker and thereby preventing potassium permeation when the channel would normally open in response to membrane depolarization and elevated intracellular calcium.

In research settings, iberiotoxin is used as a pharmacological tool to dissect BK channel function in neurons, muscle tissue, and cardiac cells. By selectively blocking BK channels, investigators can assess the contribution of these channels to action potential duration, afterhyperpolarization, and Ca2+-dependent excitability. Its use helps distinguish BK channel–mediated currents from other potassium currents.

As a venom-derived peptide, iberiotoxin is employed under appropriate safety and handling protocols in laboratory environments. It is part of a broader family of scorpion toxins that target potassium channels, each with varying selectivity profiles for BK, Kv, and other channel types.