title: The peptide pQFYRFamide is encoded on the FMRFamide precursor of the snail Helix aspersa but does not activate the FMRFamide-gated sodium current.
abstract: The complete sequence of the FMRFamide precursor cDNA from Helix aspersa is reported here. Since the 5' end of this cDNA is identical to that of the precursor that encodes the heptapeptide analogs of FLRFamide, the two transcripts are probably derived by alternative RNA splicing. A novel pentapeptide, Glp-Phe-Tyr-Arg-Phe-NH2 (pQFYRFamide), predicted from the cDNA sequence, was purified from extracts of H. aspersa ganglia and identified by mass spectroscopy. Partial gene sequences for the FMRFamide precursors of two closely related pulmonate species-Cepaea nemoralis and Polydontes acutangula-were also determined and compared with the cDNA sequence of H. aspersa and a partial gene sequence previously determined from H. pomatia. Not only are the FMRFamide-related sequences and proteolytic processing sites conserved, but the linear arrangement of these landmarks is also retained. Synthetic pQFYRFamide has some effects on the isolated heart and on neuronal potassium currents in H. aspersa that are similar to those of FMRFamide, but it does not activate the neuronal FMRFamide-gated sodium channel.
authors.affiliation: Whitney Laboratory, St. Augustine, Florida 32086-8623, USA.
authors.forename: D A
authors.initials: DA
authors.lastname: Price
authors.forename: K E
authors.initials: KE
authors.lastname: Doble
authors.forename: W
authors.initials: W
authors.lastname: Lesser
authors.forename: M J
authors.initials: MJ
authors.lastname: Greenberg
authors.forename: K M
authors.initials: KM
authors.lastname: Swiderek
authors.forename: T D
authors.initials: TD
authors.lastname: Lee
authors.forename: E M
authors.initials: EM
authors.lastname: Lutz
authors.forename: J
authors.initials: J
authors.lastname: Sommerville
authors.forename: S
authors.initials: S
authors.lastname: Falconer
authors.forename: G A
authors.initials: GA
authors.lastname: Cottrell
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002874:Chromosome Mapping; D006321:Heart / Q000187:drug effects; D006372:Helix, Snails; D008969:Molecular Sequence Data; D009206:Myocardium / Q000737:chemistry; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009474:Neurons / Q000737:chemistry / Q000187:drug effects; D009842:Oligopeptides / Q000737:chemistry / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011498:Protein Precursors / Q000737:chemistry / Q000235:genetics*; D012333:RNA, Messenger / Q000737:chemistry; D015222:Sodium Channels / Q000378:metabolism*
chemical_list: C103585:FMRFamide precursor; C097095:FaNaCh protein, Helix aspersa; C103584:Glp-phenylalanyl-tyrosyl-arginyl-phenylalaninamide; D009419:Nerve Tissue Proteins; D009842:Oligopeptides; D011498:Protein Precursors; D012333:RNA, Messenger; D015222:Sodium Channels