Interactions between dendrotoxin, a blocker of voltage-dependent potassium channels, and charybdotoxin, a blocker of calcium-activated potassium channels, at binding sites on neuronal membranes

A. L. Harvey, D. L. Marshall, F. A. De-Allie, P. N. Strong

Research output: Contribution to journalArticle

39 Citations (Scopus)

Abstract

Dendrotoxin I (DpI) from black mamba venom (Dendroaspis polylepis) has high affinity binding sites on rat brain synaptic membranes. Native DpI displaced [125I]-DpI binding with a Ki of 1 × 10-10 M, and over 90% of specific binding was displaceable. Charybdotoxin isolated from the Israeli scorpion venom (Leiurus quinquestriatus hebraeus), also displaced [125I]-DpI binding, with a Ki of approximately 3 × 10-9 M, although the displacement curve was shallower than with native DpI. Both toxins are thought to be high affinity blockers of specific K+ currents. Charybdotoxin selectively blocks some types of Ca2+-activated K+ channels, whereas dendrotoxins only block certain voltage-dependent K+ channels. The interaction between the two types of toxin at the DpI binding site is unexpected and may suggest the presence of related binding sites on different K+ channel proteins.

Original languageEnglish
Pages (from-to)394-397
Number of pages4
JournalBiochemical and Biophysical Research Communications
Volume163
Issue number1
DOIs
Publication statusPublished - 30 Aug 1989

Keywords

  • charybdotoxin
  • dendrotoxin
  • radioisotope
  • brain synaptosome
  • synaptic membrane
  • binding site
  • animal cell
  • membrane potentials
  • scorpion venoms

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