Imperatoxin I (IpTx) is a peptide toxin derived from the venom of the African scorpion Pandinus imperator.
When an action potential reaches the muscle, RyR channels open and Ca2+ becomes available in the cell to induce contraction.
The presence of Ca2+ induces the large subunit of IpTxi to hydrolyze the Sn2 fatty acyl bond from the membrane of the sarcoplasmatic reticulum.
The freed fatty acids bind to the RyR itself or to a closely associated protein linked to gating.
[4] Because IpTxi also works on the RyR channels of the heart muscles, it could potentially be used as a drug against arrhythmia.