This family consists of acidic alpha-KTx short chain scorpion toxins. These toxins named parabutoxins, block voltage-gated K channels and have extremely low pI values. Furthermore, they lack the crucial pore-plugging lysine. In addition, the second important residue of the dyad, the hydrophobic residue (Phe or Tyr) is also missing [1].

1: A subfamily of acidic alpha-K(+) toxins. Huys I, Olamendi-Portugal T, Garcia-Gomez BI, Vandenberghe I, Van Beeumen J, Dyason K, Clynen E, Zhu S, van der Walt J, Possani LD, Tytgat J; J Biol Chem 2004;279:2781-2789. PMID:14561751