Kawamura S
Department of Physiology, School of Medicine, Keio University, Tokyo, Japan.
Keio J Med. 1994 Sep;43(3):149-54. doi: 10.2302/kjm.43.149.
Vertebrate retinal photoreceptors respond to light by membrane hyperpolarization. The generation mechanism of the photoresponse, namely the phototransduction mechanism is now well characterized. Photoreceptors not only detected light, but also actively adapt to environmental light. Recent biochemical and electrophysiological studies uncovered the mechanism of light-adaptation. In this mechanism, light-induced decrease in the cytoplasmic [Ca2+] plays a major role: The [Ca2+] decrease induces the desensitization of the cell and the acceleration of the time course of the photoresponse. These effects are mediated by Ca(2+)-binding proteins named S-modulin and GCAP.
脊椎动物视网膜光感受器通过膜超极化对光作出反应。光反应的产生机制，即光转导机制，现已得到充分表征。光感受器不仅能检测光，还能积极适应环境光。最近的生化和电生理研究揭示了光适应机制。在这一机制中，光诱导的细胞质[Ca2+]降低起主要作用：[Ca2+]降低诱导细胞脱敏并加速光反应的时间进程。这些效应由名为S-调钙蛋白和鸟苷酸环化酶激活蛋白（GCAP）的钙结合蛋白介导。
