Abstract
cGMP-gated channels are essential for phototransduction in the vertebrate retina. Here we show that the affinity of these channels for cGMP in chick cones is substantially higher during the subjective night than during the subjective day. This effect persists in constant environmental conditions after entrainment to 12:12 hr light-dark cycles in vitro or in ovo. Circadian modulation of ligand affinity is a posttranslational effect and is driven by rhythms in the activities of two protein kinases: Erk and Ca2+/calmodulin-dependent protein kinase II (CaMKII). Erk is maximally active during the subjective night, whereas CaMKII is maximally active during the subjective day. Acute inhibition of these signaling pathways causes phase-dependent changes in the affinity of the channels for cGMP.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Biological Clocks / physiology
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Calcium-Calmodulin-Dependent Protein Kinase Type 2
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Calcium-Calmodulin-Dependent Protein Kinases / antagonists & inhibitors
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Calcium-Calmodulin-Dependent Protein Kinases / metabolism*
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Cells, Cultured
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Chick Embryo
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Circadian Rhythm / physiology*
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Cyclic GMP / metabolism
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Cyclic Nucleotide-Gated Cation Channels
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Darkness
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Enzyme Inhibitors / pharmacology
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Eye Proteins / metabolism
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Ion Channel Gating / physiology
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Ion Channels / metabolism*
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Ligands
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Light
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MAP Kinase Kinase 1
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Mitogen-Activated Protein Kinase Kinases / antagonists & inhibitors
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Mitogen-Activated Protein Kinases / metabolism*
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Patch-Clamp Techniques
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Protein Serine-Threonine Kinases / antagonists & inhibitors
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Retinal Cone Photoreceptor Cells / cytology
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Retinal Cone Photoreceptor Cells / metabolism*
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Signal Transduction
Substances
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Cyclic Nucleotide-Gated Cation Channels
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Enzyme Inhibitors
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Eye Proteins
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Ion Channels
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Ligands
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Protein Serine-Threonine Kinases
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Calcium-Calmodulin-Dependent Protein Kinase Type 2
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Calcium-Calmodulin-Dependent Protein Kinases
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Mitogen-Activated Protein Kinases
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MAP Kinase Kinase 1
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Mitogen-Activated Protein Kinase Kinases
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Cyclic GMP