Properties of Cyclic-Nucleotide Gated Channels Mediating Olfactory Transduction - Activation, Selectivity, and Blockage

Frings, S, Lynch, JW and Lindemann, B (1992) Properties of Cyclic-Nucleotide Gated Channels Mediating Olfactory Transduction - Activation, Selectivity, and Blockage. Journal of General Physiology, 100 1: 45-67. doi:10.1085/jgp.100.1.45

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Author Frings, S
Lynch, JW
Lindemann, B
Title Properties of Cyclic-Nucleotide Gated Channels Mediating Olfactory Transduction - Activation, Selectivity, and Blockage
Journal name Journal of General Physiology   Check publisher's open access policy
ISSN 0022-1295
Publication date 1992-07-01
Year available 1992
Sub-type Article (original research)
DOI 10.1085/jgp.100.1.45
Open Access Status File (Publisher version)
Volume 100
Issue 1
Start page 45
End page 67
Total pages 23
Place of publication NEW YORK
Publisher ROCKEFELLER UNIV PRESS
Language eng
Abstract Cyclic nucleotide-gated channels (cng channels) in the sensory membrane of olfactory receptor cells, activated after the odorant-induced increase of cytosolic cAMP concentration, conduct the receptor current that elicits electrical excitation of the receptor neurons. We investigated properties of cng channels from frog and rat using inside-out and outside-out membrane patches excised from isolated olfactory receptor cells. Channels were activated by cAMP and cGMP with activation constants of 2.5-4.0-mu-M for cAMP and 1.0-1.8 for cGMP. Hill coefficients of dose-response curves were 1.4-1.8, indicating cooperativity of ligand binding. Selectivity for monovalent alkali cations and the Na/Li mole-fraction behavior identified the channel as a nonselective cation channel, having a cation-binding site of high field strength in the pore. Cytosolic pH effects suggest the presence of an additional titratable group which, when protonated, inhibits the cAMP-induced current with an apparent pK of 5.0-5.2. The pH effects were not voltage dependent. Several blockers of Ca2+ channels also blocked olfactory cng channels. Amiloride, D 600, and diltiazem inhibited the cAMP-induced current from the cytosolic side. Inhibition constants were voltage dependent with values of, respectively, 0.1, 0.3, and 1 mM at - 60 mV, and 0.03, 0.02, and 0.2 mM at + 60 mV. Our results suggest functional similarity between frog and rat cng channels, as well as marked differences to cng channels from photoreceptors and other tissues.
Keyword Cgmp-Dependent Channel
Rod Outer Segments
Sensitive Adenylate-Cyclase
Receptor-Cells
Retinal Rods
Functional Expression
Exchange Inhibitors
Ionic Selectivity
Calcium Channels
Excised Patches
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: ResearcherID Downloads - Archived
 
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