title: RYIRFamide: a turbellarian FMRFamide-related peptide (FaRP).
abstract: FMRFamide was isolated originally from neural-tissue extracts of a bivalve mollusc, since when either authentic FMRFamide or a series of structurally-related peptides have been isolated from representative arthropods, annelids and many additional molluscs. However, to date no information exists as to the definitive presence and primary structure of a FaRP in a free-living flatworm. Here, we report the isolation and primary structure of a FaRP from the free-living turbellarian, Artioposthia triangulata, a species from which NPF has been previously structurally-characterised. Unlike molluscs and insects, in which several FaRPs are expressed, only a single member of this family was detected in this turbellarian. The primary structure of this turbellarian FaRP was established as Arg-Tyr-Ile-Arg-Phe-NH2 (RYIRFamide) and the molecular mass as 752.7 Da. These data have established unequivocally that FaRPs occur in the nervous systems of the most phylogenetically-ancient invertebrates which display bilaterally-symmetrical neuronal plans and that authentic FMRFamide is probably not the original member of the family in molecular evolutionary terms.
authors.affiliation: Comparative Neuroendocrinology Research Group, School of Clinical Medicine, Queen's University of Belfast, UK.
authors.forename: A G
authors.initials: AG
authors.lastname: Maule
authors.forename: C
authors.initials: C
authors.lastname: Shaw
authors.forename: D W
authors.initials: DW
authors.lastname: Halton
authors.forename: W J
authors.initials: WJ
authors.lastname: Curry
authors.forename: L
authors.initials: L
authors.lastname: Thim
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D019835:FMRFamide; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009479:Neuropeptides / Q000737:chemistry* / Q000302:isolation & purification; D018377:Neurotransmitter Agents / Q000737:chemistry* / Q000302:isolation & purification; D009842:Oligopeptides / Q000737:chemistry* / Q000302:isolation & purification; D014419:Turbellaria / Q000737:chemistry*
chemical_list: D009479:Neuropeptides; D018377:Neurotransmitter Agents; D009842:Oligopeptides; C086754:arginyl-tyrosyl-isoleucyl-arginyl-phenylalaninamide; D019835:FMRFamide