Biochemical mechanism of light adaptation in vertebrate photoreceptors.
Vertebrate photoreceptors can adjust their sensitivity to a wide range of light intensities spanning several orders of magnitude, the phenomenon of which is called light adaptation. Electrophysiological and biochemical studies have revealed that calcium can serve as an intracellular transmitter of light adaptation under the control of cGMP metabolism. After illumination, the cytoplasmic calcium concentration of a photoreceptor decreases, which in turn strongly activates photoreceptor guanylate cyclase. This calcium-dependent effect is mediated by a novel calcium-binding protein (recoverin) and leads to the restoration of the depleted cGMP pool after illumination.
Koch
K W
KW
Institut für Biologische Informationsverarbeitung, Forschungszentrum Jülich, Germany.
D000221:Adaptation, Ocular / Q000502:physiology*; D000818:Animals; D000951:Antigens, Neoplasm / Q000502:physiology; D002118:Calcium / Q000502:physiology; D002135:Calcium-Binding Proteins / Q000502:physiology; D005136:Eye Proteins; D006162:Guanylate Cyclase / Q000502:physiology; D051597:Hippocalcin; D006801:Humans; D008027:Light; D008074:Lipoproteins; D009419:Nerve Tissue Proteins; D010786:Photoreceptor Cells / Q000502:physiology*; D051603:Recoverin; D015398:Signal Transduction / Q000502:physiology
D000951:Antigens, Neoplasm; D002135:Calcium-Binding Proteins; D005136:Eye Proteins; D008074:Lipoproteins; D009419:Nerve Tissue Proteins; C496731:RCVRN protein, human; D051603:Recoverin; D051597:Hippocalcin; D006162:Guanylate Cyclase; D002118:Calcium