Calcium-dependent modulation of the agonist affinity of the mammalian olfactory cyclic nucleotide-gated channel by calmodulin and a novel endogenous factor

Balasubramanian, S, Lynch, JW and Barry, PH (1996) Calcium-dependent modulation of the agonist affinity of the mammalian olfactory cyclic nucleotide-gated channel by calmodulin and a novel endogenous factor. Journal of Membrane Biology, 152 1: 13-23. doi:10.1007/s002329900081


Author Balasubramanian, S
Lynch, JW
Barry, PH
Title Calcium-dependent modulation of the agonist affinity of the mammalian olfactory cyclic nucleotide-gated channel by calmodulin and a novel endogenous factor
Journal name Journal of Membrane Biology   Check publisher's open access policy
ISSN 0022-2631
Publication date 1996-07-01
Year available 1996
Sub-type Article (original research)
DOI 10.1007/s002329900081
Open Access Status Not yet assessed
Volume 152
Issue 1
Start page 13
End page 23
Total pages 11
Place of publication NEW YORK
Publisher SPRINGER VERLAG
Language eng
Abstract The calcium-dependent modulation of the affinity of the cyclic nucleotide-gated (CNG) channels for adenosine 3',5'-cyclic monophosphate (cAMP) was studied in enzymatically dissociated rat olfactory receptor neurons, by recording macroscopic cAMP-activated currents from inside-out patches excised from their dendritic knobs. Upon intracellular addition of 0.2 mM Ca2+ (0.2 Ca) the concentration of cAMP required for the activation of half-maximal current (EC(50)) was reversibly increased from 3 mu M to about 30 mu M. This Ca2+-induced affinity shift was insensitive to the calmodulin antagonist, mastoparan, was abolished irreversibly by a 2-min exposure to 3 mM Mg2+ + 2 mM EGTA (Mg + EGTA), and was not restored by the application of calmodulin (CAM). Addition of CAM plus 0.2 mM Ca2+ (0.2 Ca + CAM), further reversibly shifted the cAMP affinity from 30 mu M to about 200 mu M. This affinity shift was not affected by Mg + EGTA exposure, but was reversed by mastoparan. Thus, the former Ca2+-only effect must be mediated by an unknown endogenous factor, distinct from CAM. Removal of this factor also increased the affinity of the channel for CAM. The affinity shift induced by Ca2+-only was maintained in the presence of the nonhydrolyzable cAMP analogue, 8-bromo-cAMP and the phosphatase inhibitor, microcystin-LR, ruling out modulation by phosphodiesterases or phosphatases. Our results indicate that the olfactory CNG channels are modulated by an as yet unidentified factor distinct from CAM.
Keyword olfactory receptor neuron
CNG channel
cyclic AMP
Ca2+
calmodulin
Receptor Neurons
Cation Channel
Patch-Clamp
Ion Channel
Cells
Sensitivity
Protein
Ca2+-Calmodulin
Inhibition
Pathways
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
 
Versions
Version Filter Type
Citation counts: TR Web of Science Citation Count  Cited 47 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 48 times in Scopus Article | Citations
Google Scholar Search Google Scholar
Created: Sat, 26 Oct 2013, 02:37:06 EST by System User