Cyclic GMP and calcium: The internal messengers of excitation and adaptation in vertebrate photoreceptors

@article{Pugh1990CyclicGA,
  title={Cyclic GMP and calcium: The internal messengers of excitation and adaptation in vertebrate photoreceptors},
  author={Edward N Pugh and Trevor D. Lamb},
  journal={Vision Research},
  year={1990},
  volume={30},
  pages={1923-1948}
}
The roles of cyclic GMP (cGMP) and calcium (Ca2+) in vertebrate rod phototransduction are reviewed, with the emphasis on developments since the discovery of the cGMP-activated conductance of the rod outer segment. The first hypothesis subjected to critical examination is that cGMP acts as the sole internal messenger of excitation. This hypothesis is evaluated with a formal, quantitative model of the biochemical actions of cGMP. Application of the model shows a remarkable agreement between… Expand
Role of cGMP and Ca2+ in vertebrate photoreceptor excitation and adaptation.
TLDR
This review examines the roles of guanosine 3' ,5' -cyclic monophosphate (cGMP) and Ca2+ ions in signal transduction of vertebrate photoreceptors and suggests that Ca2- ions play an important role by controlling the formation of cGMP. Expand
Regulation of intracellular cyclic GMP concentration by light and calcium in electropermeabilized rod photoreceptors
TLDR
It is concluded that changes in the intracellular calcium concentration during visual transduction may have more complex effects on the recovery of the photoresponse than can be accounted for solely by guanylate cyclase activation. Expand
Factors that affect regulation of cGMP synthesis in vertebrate photoreceptors and their genetic link to human retinal degeneration
TLDR
Two isozymes of membrane photoreceptor guanylyl cyclase (retGC) have been identified in rods and cones that are regulated by Ca2+-binding proteins, GCAPs, but concentrations above 500 nM typical for dark-adapted photoreceptors turn them into inhibitors of retGC. Expand
Modulation of the cGMP-gated channel of rod photoreceptor cells by calmodulin
TLDR
Calmodulin, a Ca2+-binding protein present in the rod outer segment, increases the apparent Michaelis constant of the channel for cGMP, which results in a decrease in the rate of cation influx into the rods outer segment and has the effect of increasing the sensitivity of theChannel to small changes in cG MP levels during phototrans-duction. Expand
Regulation of intracellular cyclic GMP concentration by light and calcium in electropermeabilized rod photoreceptors
Light adaptation in vertebrate photoreceptors is thought to be mediated through a number of biochemical feedback reactions that reduce the sensitivity of the photoreceptor and accelerate the kineticsExpand
LIGHT‐SENSITIVITY MODULATING PROTEIN IN FROG RODS
  • S. Kawamura
  • Biology, Medicine
  • Photochemistry and photobiology
  • 1992
TLDR
High light‐sensitivity of photoreceptors under the dark‐adapted condition is explained by isolated a protein that binds to disk membranes at high Ca2+ concentrations and is termed ‘sensitivity‐modulating protein’ or ‘S‐modulin’. Expand
Regulation of cGMP synthesis in photoreceptors: role in signal transduction and congenital diseases of the retina.
  • A. Dizhoor
  • Biology, Medicine
  • Cellular signalling
  • 2000
TLDR
Calcium feedback in vertebrate photoreceptors regulates synthesis of cGMP, a second messenger in phototransduction, and contributes to photoreceptor recovery and light adaptation. Expand
Two pathways of rod photoreceptor cell death induced by elevated cGMP
TLDR
It is found that abolishing expression of CNG channels prolongs rod survival caused by elevated cGMP in a PDE6 mutant mouse model, and this observation supports the use of channel blockers to delay rod death, which is expected to prolong useful vision through enhanced cone survival. Expand
Regulation of the rod photoreceptor cyclic nucleotide-gated channel.
TLDR
It is shown that endogenous calmodulin, but not other Ca2+ dependent proteins, binds and modulates the rod cGMP-gated channel in bovine rod outer segments and that the beta-subunit of the channel is phosphorylated by endogenous and exogenous casein kinase 2. Expand
Species differences in the response of mammalian photoreceptor cyclic GMP and PIII to a reduction in calcium
TLDR
Changes in the content of cyclic GMP, induced by exposure of isolated, dark-adapted mouse, cat and dog retinas to media depleted of calcium, have been compared with the amplitude of the trans-retinal PIII to imply species variation in the enzymes maintaining cGMP homeostasis in photoreceptors, but also in phototransduction and allied processes. Expand
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TLDR
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TLDR
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TLDR
The coming together of electrophysiology, biochemistry, and molecular genetics affords new opportunities in unraveling the molecular mechanism of visual transduction, and the interplay of cGMP, calcium ion, and phosphoinositides in excitation and adaptation is delineated. Expand
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TLDR
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TLDR
It is shown that the guanylate cyclase activity of unilluminated bovine rod outer segments increases markedly when the calcium level is lowered from 200 nM to 50 nM, and the highly cooperative activation of guany Late cyclase by the light-induced lowering of Cai is likely to be a key event in restoring the dark current after excitation. Expand
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TLDR
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