Butantoxin (BuTX) is a compound of the venom of three Brazilian and an Argentinean scorpion species of the genus Tityus.
[1] The scorpion toxins that are selective for K+ channels (KTx) are classified into families: α-, β- and γ-KTx.
The N-terminal C2-C5 disulfide bond is unique to butantoxin; the other 3 are present in all members of the short-chain scorpion toxin family.
While this unique disulfide bond is not likely to play a role in the stability of butantoxin, it may affect receptor specificity.
[1][4] The highly conserved primary sequence and folding of butantoxin suggests these contribute to essential aspects of the toxins effectiveness.
Due to variability in the primary sequence, all subfamily members have a different affinity for the various K+ channels.
[1][2][5] Butantoxin has also been shown to inhibit both T-cell proliferation and the interleukin-2 production by antigen-stimulated T-helper cells.
[2] Based on the results obtained from docking simulations, butantoxin may require only 6 main molecular contacts to interact with the Kv1.2 channel.
[1][5] It is about 60 times less potent than the more well known maurotoxin (MTX), another member of the short-chain scorpion toxin family.