Location of a ligand recognition site of FMRFamide-gated Na(+) channels.
The second FMRFamide-gated Na(+) channel (HtFaNaC), from Helisoma trivolvis, has been cloned. HtFaNaC has some different pharmacological properties to HaFaNaC, from Helix aspersa, which has enabled a rational approach to be made to start to identify the FMRFamide recognition site. Several chimeras were made by switching sections between the channels. The differences in sensitivity to FMRFamide, and amiloride, were assessed after expression in Xenopus oocytes. The data suggest that a recognition site for FMRFamide, and the potentiating action of amiloride, resides in a sequence of about 120 amino acids in the extracellular loop proximal to the first transmembrane segment.
Cottrell
G A
GA
School of Biology, University of St. Andrews, Fife, UK. gac@st-andrews.ac.uk
Jeziorski
M C
MC
Green
K A
KA
D000584:Amiloride / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D004232:Diuretics / Q000494:pharmacology; D004594:Electrophysiology; D019835:FMRFamide / Q000494:pharmacology*; D008969:Molecular Sequence Data; D008974:Mollusca / Q000378:metabolism*; D009865:Oocytes; D011993:Recombinant Fusion Proteins / Q000187:drug effects / Q000502:physiology; D017386:Sequence Homology, Amino Acid; D015222:Sodium Channels / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D014162:Transfection; D014982:Xenopus laevis
D004232:Diuretics; C097095:FaNaCh protein, Helix aspersa; D011993:Recombinant Fusion Proteins; D015222:Sodium Channels; D019835:FMRFamide; D000584:Amiloride