A peptide-gated ion channel from the freshwater polyp Hydra

J Biol Chem. 2007 Nov 30;282(48):35098-103. doi: 10.1074/jbc.M706849200. Epub 2007 Oct 2.


Chemical transmitters are either low molecular weight molecules or neuropeptides. As a general rule, neuropeptides activate only slow metabotropic receptors. To date, only one exception to this rule is known, the FMRFamide-activated Na(+) channel (FaNaC) from snails. Until now FaNaC has been regarded as a curiosity, and it was not known whether peptide-gated ionotropic receptors are also present in other animal groups. Nervous systems first evolved in cnidarians, which extensively use neuropeptides. Here we report cloning from the freshwater cnidarian Hydra of a novel ion channel (Hydra sodium channel, HyNaC) that is directly gated by the neuropeptides Hydra-RFamides I and II and is related to FaNaC. The cells expressing HyNaC localize to the base of the tentacles, adjacent to the neurons producing the Hydra-RFamides, suggesting that the peptides are the natural ligands for this channel. Our results suggest that neuropeptides were already used for fast transmission in ancient nervous systems.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acid Sensing Ion Channels
  • Amino Acid Sequence
  • Animals
  • Cloning, Molecular
  • Hydra
  • In Situ Hybridization
  • Ions
  • Ligands
  • Membrane Proteins / chemistry
  • Molecular Sequence Data
  • Nerve Tissue Proteins / chemistry
  • Peptides / chemistry*
  • Phylogeny
  • Rats
  • Sequence Homology, Amino Acid
  • Sodium Channels / chemistry
  • Sodium Channels / physiology*


  • Acid Sensing Ion Channels
  • FaNaCh protein, Helix aspersa
  • Ions
  • Ligands
  • Membrane Proteins
  • Nerve Tissue Proteins
  • Peptides
  • Sodium Channels

Associated data

  • GENBANK/AM393878
  • GENBANK/AM393879
  • GENBANK/AM393880
  • GENBANK/AM393881