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Single-channel currents of a peptide-gated sodium channel expressed in Xenopus oocytes.
Zhainazarov AB
,
Cottrell GA
.
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1. Single-channel recordings were made from outside-out membrane patches of Xenopus oocytes injected with the cDNA clone FaNaCh, which encodes a peptide-gated Na+ channel from Helix aspersa. 2. The natural peptides FMRFamide and FLRFamide only activated unitary currents in oocytes injected with FaNaCh; the EC50 values were 1.8 and 11.7 microM, respectively. 3. The slope conductance of the channel was 9.2 pS for both peptides. 4. With FMRFamide, the open probability (Po) of the channel was 0.06 at 0.3 microM and 0.76 at 30 microM, whereas for FLRFamide the open probability increased from 0.04 at 1.8 microM to 0.49 at 50 microM. The Hill coefficient was greater than 1 for both peptides. 5. High concentrations of each peptide evoked very fast flickering between open and closed states which led to decreased unitary current amplitude. 6. At low doses, brief single openings and bursts of longer openings occurred. With higher doses, the occurrence of the brief openings declined and the number of longer openings increased; the duration of the longer openings was shorter with FLRFamide than with FMRFamide. 7. For each peptide, frequency distribution histograms of open events were best fitted by the sum of two exponential components, suggesting the existence of two open states of the channel. Closed events were fitted by the sum of three components, suggesting the existence of three closed states. 8. The data were analysed according to a five-state model in which the brief openings correspond to a single liganded open form of the channel and the longer openings to a doubly liganded open form. According to this interpretation, the greater whole-cell response observed with FMRFamide than with FLRFamide results mostly from a slower closing rate constant for the longer (doubly liganded) channel openings.
Canessa,
Amiloride-sensitive epithelial Na+ channel is made of three homologous subunits.
1994, Pubmed,
Xenbase
Canessa,
Amiloride-sensitive epithelial Na+ channel is made of three homologous subunits.
1994,
Pubmed
,
Xenbase
Canessa,
Epithelial sodium channel related to proteins involved in neurodegeneration.
1993,
Pubmed
,
Xenbase
Colombaioni,
The neuropeptide FMRF-amide decreases both the Ca2+ conductance and a cyclic 3',5'-adenosine monophosphate-dependent K+ conductance in identified molluscan neurons.
1985,
Pubmed
Colquhoun,
Fast events in single-channel currents activated by acetylcholine and its analogues at the frog muscle end-plate.
1985,
Pubmed
Colquhoun,
On the stochastic properties of bursts of single ion channel openings and of clusters of bursts.
1982,
Pubmed
Cottrell,
Multiple receptor sites for a molluscan peptide (FMRFamide) and related peptides of Helix.
1987,
Pubmed
Cottrell,
The first peptide-gated ion channel.
1997,
Pubmed
,
Xenbase
Cottrell,
Multiple actions of a molluscan cardioexcitatory neuropeptide and related peptides on identified Helix neurones.
1984,
Pubmed
Cottrell,
The neuropeptide Phe-Met-Arg-Phe-NH2 (FMRFamide) can activate a ligand-gated ion channel in Helix neurones.
1990,
Pubmed
Driscoll,
Developmental and abnormal cell death in C. elegans.
1992,
Pubmed
Green,
The neuropeptide Phe-Met-Arg-Phe-NH2 (FMRFamide) directly gates two ion channels in an identified Helix neurone.
1994,
Pubmed
Greenberg,
Relationships among the FMRFamide-like peptides.
1992,
Pubmed
Hamill,
Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches.
1981,
Pubmed
Huang,
Gene interactions affecting mechanosensory transduction in Caenorhabditis elegans.
1994,
Pubmed
Lingueglia,
Expression cloning of an epithelial amiloride-sensitive Na+ channel. A new channel type with homologies to Caenorhabditis elegans degenerins.
1993,
Pubmed
,
Xenbase
Lingueglia,
Cloning of the amiloride-sensitive FMRFamide peptide-gated sodium channel.
1995,
Pubmed
,
Xenbase
Lutz,
Structure of cDNA clones and genomic DNA FMRFamide-related peptides (FaRPs) in Helix.
1992,
Pubmed
Price,
The peptide pQFYRFamide is encoded on the FMRFamide precursor of the snail Helix aspersa but does not activate the FMRFamide-gated sodium current.
1996,
Pubmed
Waldmann,
Molecular cloning of a non-inactivating proton-gated Na+ channel specific for sensory neurons.
1997,
Pubmed
Waldmann,
A proton-gated cation channel involved in acid-sensing.
1997,
Pubmed
,
Xenbase
