A new sea anemone peptide, APETx2, inhibits ASIC3, a major acid-sensitive channel in sensory neurons

EMBO J. 2004 Apr 7;23(7):1516-25. doi: 10.1038/sj.emboj.7600177. Epub 2004 Mar 25.


From a systematic screening of animal venoms, we isolated a new toxin (APETx2) from the sea anemone Anthopleura elegantissima, which inhibits ASIC3 homomeric channels and ASIC3-containing heteromeric channels both in heterologous expression systems and in primary cultures of rat sensory neurons. APETx2 is a 42 amino-acid peptide crosslinked by three disulfide bridges, with a structural organization similar to that of other sea anemone toxins that inhibit voltage-sensitive Na+ and K+ channels. APETx2 reversibly inhibits rat ASIC3 (IC50=63 nM), without any effect on ASIC1a, ASIC1b, and ASIC2a. APETx2 directly inhibits the ASIC3 channel by acting at its external side, and it does not modify the channel unitary conductance. APETx2 also inhibits heteromeric ASIC2b+3 current (IC50=117 nM), while it has less affinity for ASIC1b+3 (IC50=0.9 microM), ASIC1a+3 (IC50=2 microM), and no effect on the ASIC2a+3 current. The ASIC3-like current in primary cultured sensory neurons is partly and reversibly inhibited by APETx2 with an IC50 of 216 nM, probably due to the mixed inhibitions of various co-expressed ASIC3-containing channels.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acid Sensing Ion Channels
  • Amino Acid Sequence
  • Animals
  • COS Cells
  • Cells, Cultured
  • Chlorocebus aethiops
  • Cnidarian Venoms / chemistry*
  • Cnidarian Venoms / genetics
  • Cnidarian Venoms / metabolism*
  • Humans
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Mice
  • Models, Molecular
  • Molecular Sequence Data
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / metabolism*
  • Neurons, Afferent / cytology
  • Neurons, Afferent / metabolism*
  • Oocytes / physiology
  • Patch-Clamp Techniques
  • Peptides / chemistry
  • Peptides / genetics
  • Peptides / metabolism
  • Potassium Channels / metabolism
  • Protein Structure, Tertiary
  • Protein Subunits / genetics
  • Protein Subunits / metabolism
  • Rats
  • Sea Anemones / chemistry*
  • Sodium Channels / genetics
  • Sodium Channels / metabolism*
  • Xenopus laevis


  • APETx1, Anthopleura elegantissima
  • APETx2 protein, Anthopleura elegantissima
  • ASIC1 protein, human
  • ASIC1 protein, mouse
  • ASIC3 protein, rat
  • Acid Sensing Ion Channels
  • Cnidarian Venoms
  • Membrane Proteins
  • Nerve Tissue Proteins
  • Peptides
  • Potassium Channels
  • Protein Subunits
  • Sodium Channels