This family consists of toxin-like peptides that are isolated from the venom of Buthus martensii Karsch scorpion. The precursor consists of 60 amino acid residues, with a putative signal peptide of 28 residues and an extra residue, and a mature peptide of 31 residues with an amidated C-terminal. The peptides share close homology with other scorpion K+ channel toxins and should present a common three-dimensional fold - the Cysteine -Stabilised alphabeta (CSalphabeta) motif [3]. This family acts by blocking small conductance calcium activated potassium ion channels in their victim [1,2].

1: Solution structure of BmP02, a new potassium channel blocker from the venom of the Chinese scorpion Buthus martensi Karsch. Xu Y, Wu J, Pei J, Shi Y, Ji Y, Tong Q; Biochemistry 2000;39:13669-13675. PMID:11076505

2: Molecular cloning and sequencing of two 'short chain' and two 'long chain' K(+) channel-blocking peptides from the Chinese scorpion Buthus martensii Karsch. Zhu S, Li W, Zeng X, Jiang D, Mao X, Liu H; FEBS Lett 1999;457:509-514. PMID:10471839

3: Precursor nucleotide sequence and genomic organization of BmTXKS1, a new scorpion toxin-like peptide from Buthus martensii Karsch. Zhu SY, Li WX, Zeng XC; Toxicon 2001;39:1291-1296. PMID:11384716