Purification, molecular cloning and functional characterization of HelaTx1 (Heterometrus laoticus): The first member of a new κ-KTX subfamily

Thomas Vandendriessche, Ivan Kopljar, David Paul Jenkins, Elia Diego-Garcia, Yousra Abdel-Mottaleb, Elke Vermassen, Elke Clynen, Liliane Schoofs, Heike Wulff, Dirk Snyders, Jan Tytgat

Research output: Contribution to journalArticlepeer-review

27 Scopus citations


Given their medical importance, most attention has been paid toward the venom composition of scorpions of the Buthidae family. Nevertheless, research has shown that the venom of scorpions of other families is also a remarkable source of unique peptidyl toxins. The κ-KTx family of voltage-gated potassium channel (VGPC) scorpion toxins is hereof an example. From the telson of the scorpion Heterometrus laoticus (Scorpionidae), a peptide, HelaTx1, with unique primary sequence was purified through HPLC and sequenced by Edman degradation. Based on the amino acid sequence, the peptide could be cloned and the cDNA sequence revealed. HelaTx1 was chemically synthesized and functionally characterized on VGPCs of the Shaker-related, Shab-related, Shaw-related and Shal-related subfamilies. Furthermore, the toxin was also tested on small- and intermediate conductance Ca 2+-activated K + channels. From the channels studied, K v1.1 and K v1.6 were found to be the most sensitive (K v1.1 EC 50 = 9.9 ± 1.6 μM). The toxin did not alter the activation of the channels. Competition experiments with TEA showed that the toxin is a pore blocker. Mutational studies showed that the residues E353 and Y379 in the pore of K v1.1 act as major interaction points for binding of the toxin. Given the amino acid sequence, the predicted secondary structure and the biological activity on VGPCs, HelaTx1 should be included in the κ-KTX family. Based on a phylogenetic study, we rearranged this family of VGPC toxins into five subfamilies and suggest that HelaTx1 is the first member of the new κ-KTx5 subfamily.

Original languageEnglish (US)
Pages (from-to)1307-1317
Number of pages11
JournalBiochemical Pharmacology
Issue number9
StatePublished - May 1 2012


  • cDNA
  • Electrophysiology
  • Heterometrus laoticus
  • Patch clamp
  • Scorpion toxin
  • Voltage-gated potassium channel

ASJC Scopus subject areas

  • Pharmacology
  • Biochemistry


Dive into the research topics of 'Purification, molecular cloning and functional characterization of HelaTx1 (Heterometrus laoticus): The first member of a new κ-KTX subfamily'. Together they form a unique fingerprint.

Cite this