scholarly journals A Cyclic Nucleotide-Gated Channel, HvCNGC2-3, Is Activated by the Co-Presence of Na+ and K+ and Permeable to Na+ and K+ Non-Selectively

Plants ◽  
2018 ◽  
Vol 7 (3) ◽  
pp. 61 ◽  
Author(s):  
Izumi Mori ◽  
Yuichi Nobukiyo ◽  
Yoshiki Nakahara ◽  
Mineo Shibasaka ◽  
Takuya Furuichi ◽  
...  
Keyword(s):  
Cyclic Nucleotide ◽  
Expression System ◽  
Reversal Potential ◽  
Amino Acid Replacement ◽  
Bathing Solution ◽  
Xenopus Laevis Oocyte ◽  
Electrophysiological Properties ◽  
Cyclic Monophosphate ◽  
Gated Channel ◽  
Canonical Motif

Cyclic nucleotide-gated channels (CNGCs) have been postulated to contribute significantly in plant development and stress resistance. However, their electrophysiological properties remain poorly understood. Here, we characterized barley CNGC2-3 (HvCNGC2-3) by the two-electrode voltage-clamp technique in the Xenopus laevis oocyte heterologous expression system. Current was not observed in X. laevis oocytes injected with HvCNGC2-3 complementary RNA (cRNA) in a bathing solution containing either Na+ or K+ solely, even in the presence of 8-bromoadenosine 3′,5′-cyclic monophosphate (8Br-cAMP) or 8-bromoguanosine 3′,5′-cyclic monophosphate (8Br-cGMP). A weakly voltage-dependent slow hyperpolarization-activated ion current was observed in the co-presence of Na+ and K+ in the bathing solution and in the presence of 10 µM 8Br-cAMP, but not 8Br-cGMP. Permeability ratios of HvCNGC2-3 to K+, Na+ and Cl− were determined as 1:0.63:0.03 according to reversal-potential analyses. Amino-acid replacement of the unique ion-selective motif of HvCNGC2-3, AQGL, with the canonical motif, GQGL, resulted in the abolition of the current. This study reports a unique two-ion-dependent activation characteristic of the barley CNGC, HvCNGC2-3.

Sweet taste transduction in hamster: sweeteners and cyclic nucleotides depolarize taste cells by reducing a K+ current

1996 ◽  
Vol 75 (3) ◽  
pp. 1256-1263 ◽  
Author(s):  
T. A. Cummings ◽  
C. Daniels ◽  
S. C. Kinnamon
Keyword(s):  
Cyclic Nucleotides ◽  
Cyclic Nucleotide ◽  
Taste Receptor ◽  
Reversal Potential ◽  
Taste Cell ◽  
K Channel ◽  
Cyclic Monophosphate ◽  
Taste Cells ◽  
Voltage Dependent ◽  
K Current

1. The gigaseal voltage-clamp technique was used to record responses of hamster taste receptor cells to synthetic sweeteners and cyclic nucleotides. Voltage-dependent currents and steady-state currents were monitored during bath exchanges of saccharin, two high-potency sweeteners, 8-chlorophenylthio-adenosine 3',5'-cyclic monophosphate (8cpt-cAMP), and dibutyryl-guanosine 3',5'-cyclic monophosphate (db-cGMP). 2. Of the 237 fungiform taste cells studied, only one in eight was sweet responsive. Outward currents, both voltage-dependent and resting, were reduced by all of the sweeteners tested in sweet-responsive taste cells, whereas these currents were unaffected by sweeteners in sweet-unresponsive taste cells. 3. In every sweet-responsive cell tested, 8cpt-cAMP and db-cGMP mimicked the response to the sweeteners, but neither nucleotide elicited responses in sweet-unresponsive cells. Thus there was a one-to-one correlation between sweet responsivity and cyclic nucleotide responsivity. 4. Sweet responses showed cross adaptation with cyclic nucleotide responses. This indicates that the same ion channel is modulated by sweeteners and cyclic nucleotides. 5. The sweetener- and cyclic nucleotide-blocked current had an apparent reversal potential of -50 mV, which was close to the potassium reversal potential in these experiments. In addition, there was no effect of sweeteners and cyclic nucleotides in the presence of the K+ channel blocker tetraethylammonium bromide (TEA). These data suggest that block of a resting, TEA-sensitive K+ current is the final common step leading to taste cell depolarization during sweet transduction. 6. These data, together with data from a previous study (Cummings et al. 1993), suggest that both synthetic sweeteners and sucrose utilize second-messenger pathways that block a resting K+ conductance to depolarize the taste cell membrane.

scholarly journals The Complex Story of Plant Cyclic Nucleotide-Gated Channels

2021 ◽  
Vol 22 (2) ◽  
pp. 874
Author(s):  
Edwin Jarratt-Barnham ◽  
Limin Wang ◽  
Youzheng Ning ◽  
Julia M. Davies
Keyword(s):  
Arabidopsis Thaliana ◽  
Stress Response ◽  
Complex Formation ◽  
Cyclic Nucleotides ◽  
Cyclic Nucleotide ◽  
Cation Channels ◽  
Cyclic Monophosphate ◽  
Cyclic Nucleotide Gated Channels ◽  
Gated Channel

Plant cyclic nucleotide-gated channels (CNGCs) are tetrameric cation channels which may be activated by the cyclic nucleotides (cNMPs) adenosine 3′,5′-cyclic monophosphate (cAMP) and guanosine 3′,5′-cyclic monophosphate (cGMP). The genome of Arabidopsis thaliana encodes 20 CNGC subunits associated with aspects of development, stress response and immunity. Recently, it has been demonstrated that CNGC subunits form heterotetrameric complexes which behave differently from the homotetramers produced by their constituent subunits. These findings have widespread implications for future signalling research and may help explain how specificity can be achieved by CNGCs that are known to act in disparate pathways. Regulation of complex formation may involve cyclic nucleotide-gated channel-like proteins.

Reconstitution and characterization of two forms of cyclic nucleotide-gated channels from skeletal muscle

1996 ◽  
Vol 271 (6) ◽  
pp. E1051-E1060 ◽  
Author(s):  
L. C. Santy ◽  
G. Guidotti
Keyword(s):  
Skeletal Muscle ◽  
Cyclic Nucleotide ◽  
Rod Outer Segments ◽  
Channel Activity ◽  
Cyclic Monophosphate ◽  
Cyclic Nucleotide Gated Channels ◽  
Muscle Plasma Membrane ◽  
Gated Channel ◽  
Two Peaks

A cyclic nucleotide-gated channel present in skeletal muscle plasma membrane has previously been identified as being responsible for insulin-activated sodium entry into muscle cells (J. E. M. McGeoch and G. Guidotti. J. Biol. Chem. 267:832-841, 1992). We have isolated this channel activity to further study and characterize it. The channel was solubilized from rabbit skeletal muscle sarcolemma and functionally reconstituted into phospholipid vesicles, as assayed by patch-clamp analysis of the reconstituted proteins. Channel activity was isolated by 8-bromo-guanosine 3',5'-cyclic monophosphate affinity chromatography, producing two distinct peaks of cyclic nucleotide-gated channel activity. These two types of channel activity differ in guanosine 3',5'-cyclic monophosphate affinity and in the ability to be opened by adenosine 3',5'-cyclic monophosphate. The cyclic nucleotide-gated channel from rod outer segments also forms two peaks of activity when purified in this manner. The presence of two forms of channel activity could have implications for the mechanism of insulin-activated sodium entry.

scholarly journals Systemic administration of ivabradine, a hyperpolarization‐activated cyclic nucleotide‐gated channel inhibitor, blocks spontaneous absence seizures

Epilepsia ◽  
2021 ◽  
Author(s):  
Yasmine Iacone ◽  
Tatiana P. Morais ◽  
François David ◽  
Francis Delicata ◽  
Joanna Sandle ◽  
...  
Keyword(s):  
Cyclic Nucleotide ◽  
Systemic Administration ◽  
Absence Seizures ◽  
Gated Channel

Two opposite effects of ATP on the apparent sensitivity of the cGMP-gated channel of the carp retinal cone

1997 ◽  
Vol 14 (4) ◽  
pp. 609-615 ◽  
Author(s):  
Shu-Ichi Watanabe ◽  
Jing Shen
Keyword(s):  
Cone Photoreceptors ◽  
Apparent Affinity ◽  
Enhancing Effect ◽  
Cyclic Monophosphate ◽  
Maximum Current ◽  
Gated Channel ◽  
Retinal Cone ◽  
A Current

AbstractEffects of ATP on the activity of cGMP-gated channels from carp cone photoreceptors were studied. In 29% of the patches examined (N = 45), ATP (1 mM) enhanced a current evoked by cGMP (20 μM, up to about 100%), in 33%, ATP suppressed it by up to about 90%, and in the remaining 38%, ATP had no effect. ATP showed similar effects on a current evoked by 8-bromoguanosine 3′,5′-cyclic monophosphate (2 μM, enhancing in 42% of the patches, suppressing in 25%, no effect in 33%, N = 12), suggesting that the effects were not through modulation of the phosphodiesterase. Both of the effects, enhancement and suppression, were produced by a change in apparent affinity for cGMP, since (1) the maximum current evoked by cGMP of the saturating concentration (≥1 mM) was not affected, and (2) the A1/2 value decreased by approximately 45% (N = 2) or increased by approximately 25% (N = 2). A lower pH (approximately 6) facilitated the enhancing effect. ATP-γ-S (1 mM) showed a suppressing effect in 80% of the patches and no effect in 20% of the patches (N = 10). However, ATP-γ-S did not show an enhancing effect. Thus, ATP had two opposite effects through different mechanisms on the apparent sensitivity of the channel to cGMP; increasing and decreasing.

Expression of the olfactory cyclic nucleotide gated channel (CNG1) in the rat brain

Neuroreport ◽  
1995 ◽  
Vol 6 (10) ◽  
pp. 1459-1463 ◽  
Author(s):  
Alaa El-Din El-Husseini ◽  
Christopher Bladen ◽  
Steven R. Vincent
Keyword(s):  
Rat Brain ◽  
Cyclic Nucleotide ◽  
Gated Channel

Impaired Opsin Targeting and Cone Photoreceptor Migration in the Retina of Mice Lacking the Cyclic Nucleotide-Gated Channel CNGA3

2005 ◽  
Vol 46 (4) ◽  
pp. 1516 ◽  
Author(s):  
Stylianos Michalakis ◽  
Heidi Geiger ◽  
Silke Haverkamp ◽  
Franz Hofmann ◽  
Andrea Gerstner ◽  
...  
Keyword(s):  
Cyclic Nucleotide ◽  
Cone Photoreceptor ◽  
Gated Channel

Divalent cations block the cyclic nucleotide-gated channel of olfactory receptor neurons

1993 ◽  
Vol 69 (5) ◽  
pp. 1758-1768 ◽  
Author(s):  
F. Zufall ◽  
S. Firestein
Keyword(s):  
Cyclic Amp ◽  
Calcium Channels ◽  
Cyclic Nucleotide ◽  
Olfactory Receptor ◽  
Single Channel ◽  
Divalent Cations ◽  
Olfactory Receptor Neurons ◽  
Gated Channel ◽  
Receptor Neurons ◽  
Single Channel Currents

1. The effects of external divalent cations on odor-dependent, cyclic AMP-activated single-channel currents from olfactory receptor neurons of the tiger salamander (Ambystoma tigrinum) were studied in inside-out membrane patches taken from dendritic regions of freshly isolated sensory cells. 2. Channels were reversibly activated by 100 microM cyclic AMP. In the absence of divalent cations, the channel had a linear current-voltage relation giving a conductance of 45 pS. With increasing concentrations of either Ca2+ or Mg2+ in the external solution, the channel displayed a rapid flickering behavior. At higher concentrations of divalent cations, the transitions were too rapid to be fully resolved and appeared as a reduction in mean unitary single-channel current amplitude. 3. This effect was voltage dependent, and on analysis was shown to be due to an open channel block by divalent ions. In the case of Mg2+, the block increased steadily with hyperpolarization. In contrast, for Ca2+ the block first increased with hyperpolarization and then decreased with further hyperpolarization beyond -70 mV, providing evidence for Ca2+ permeation of this channel. 4. This block is similar to that seen in voltage-gated calcium channels. Additionally, the cyclic nucleotide-gated channel shows some pharmacological similarities with L-type calcium channels, including a novel block of the cyclic nucleotide channel by nifedipine (50 microM). 5. Our results indicate that the sensory generator current simultaneously depends on the presence of the second messenger and on the membrane potential of the olfactory neuron.

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