Garcia-Valdes, J., Zamudio, F.Z., Toro, L., Possan, L.D. (2001). Slotoxin, KTx1.11, a new scorpion peptide blocker of MaxiK channels that differentiates between and + (1 or 4) complexes.  FEBS Lett. 505(3): 369--373.

FBrf0139859

Research paper

A novel peptide from Centruroides noxius Hoffmann scorpion venom was isolated and sequenced. The 37 amino acid peptide belongs to the charybdotoxin sub-family (alphaKTx1) and was numbered member 11. alphaKTx1.11 has 75% sequence identity with iberiotoxin and 54% with charybdotoxin. alphaKTx1.11 revealed specificity for mammalian MaxiK channels (hSlo), thus, was named slotoxin. Slotoxin blocks the MaxiK pore-forming alpha subunit reversibly (K(d)=1.5 nM). Slotoxin association with alpha+beta (beta1 or beta4) channels was approximately 10 times slower than iberiotoxin and charybdotoxin, leading to a lack of effect on alpha+beta4 when tested at 100 nM for 5 min. Thus, slotoxin is a better tool to distinguish MaxiK alpha+beta complexes.