title: A peptide-gated ion channel from the freshwater polyp Hydra.
abstract: 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.
authors.affiliation: Institute of Physiology II, University of Würzburg, D-97070 Würzburg, Germany.
authors.forename: Andjelko
authors.initials: A
authors.lastname: Golubovic
authors.forename: Anne
authors.initials: A
authors.lastname: Kuhn
authors.forename: Michael
authors.initials: M
authors.lastname: Williamson
authors.forename: Hubert
authors.initials: H
authors.lastname: Kalbacher
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Holstein
authors.forename: Cornelis J P
authors.initials: CJ
authors.lastname: Grimmelikhuijzen
authors.forename: Stefan
authors.initials: S
authors.lastname: Gründer
mesh_terms: D062565:Acid Sensing Ion Channels; D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D006829:Hydra; D017403:In Situ Hybridization; D007477:Ions; D008024:Ligands; D008565:Membrane Proteins / Q000737:chemistry; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000737:chemistry; D010455:Peptides / Q000737:chemistry*; D010802:Phylogeny; D051381:Rats; D017386:Sequence Homology, Amino Acid; D015222:Sodium Channels / Q000737:chemistry / Q000502:physiology*
chemical_list: D062565:Acid Sensing Ion Channels; C097095:FaNaCh protein, Helix aspersa; D007477:Ions; D008024:Ligands; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D010455:Peptides; D015222:Sodium Channels