Pi5 and Pi6, two undescribed peptides from the venom of the scorpion Pandinus imperator and their effects on K+-channels

T. Olamendi-Portugal, A. Csoti, J. M. Jimenez-Vargas, F. Gomez-Lagunas, G. Panyi, L. D. Possani

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

This work reports the isolation, chemical and functional characterization of two previously unknown peptides purified from the venom of the scorpion Pandinus imperator, denominated Pi5 and Pi6. Pi5 is a classical K+-channel blocking peptide containing 33 amino acid residues with 4 disulfide bonds. It is the first member of a new subfamily, here defined by the systematic number α-KTx 24.1. Pi6 is a peptide of unknown real function, containing only two disulfide bonds and 28 amino acid residues, but showing sequence similarities to the κ-family of K-channel toxins. The systematic number assigned is κ-KTx2.9. The function of both peptides was assayed on Drosophila Shab and Shaker K+-channels, as well as four different subtypes of voltage-dependent K+-channels: hKv1.1, hKv1.2, hKv1.3 and hKv1.4. The electrophysiological assays showed that Pi5 inhibited Shaker B, hKv1.1, hKv1.2 and hKv1.3 channels with Kd = 540 nM, Kd = 92 nM and Kd = 77 nM, respectively, other studied channels were not affected. Of the channels tested only hKv1.2 and hKv1.3 were inhibited at 100 nM concentration of Pi6, the remaining current fractions were 68% and 77%, respectively. Thus, Pi5 and Pi6 are high nanomolar affinity non-selective blockers of hKv1.2 and hKv1.3 channels.

Original languageEnglish
Pages (from-to)136-144
Number of pages9
JournalToxicon
Volume133
DOIs
Publication statusPublished - Jul 1 2017

Keywords

  • Amino acid sequence
  • Ion-channel
  • K-channel blocker
  • Pandinus imperator
  • Scorpion toxin

ASJC Scopus subject areas

  • Toxicology

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