Mechanisms regulating variability of the single photon responses of mammalian rod photoreceptors
Mechanisms regulating variability of the single photon responses of mammalian rod photoreceptors
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DOI：
10.1016/s0896-6273(02)00822-x
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发表时间：
2002-08-15
期刊：
影响因子：
16.2
通讯作者：
Rieke, F
中科院分区：
文献类型：
--
作者：
Field, GD;Rieke, F
杆状光感受器单光子响应的可变性限制了编码光子吸收的数量和时间的准确性。我们研究了哺乳动物视杆的单光子反应波动的程度以及控制这些波动的机制。哺乳动物的杆状体，比如蟾蜍的杆状体，对单个光子产生的反应，其波动幅度比单分子产生的其他常见信号小3-4倍。我们使用测量波动的性质来约束单光子响应如何被调节的模型。无论是视紫红质活性的反馈控制还是转导级联内的饱和，都与实验结果不一致。然而，测量到的反应可以用视紫红质的多步关闭或多步关闭和饱和的结合来解释。
Variability in the single photon responses of rod photoreceptors limits the accuracy with which the number and timing of photon absorptions are encoded. We investigated how much single photon responses of mammalian rods fluctuate and what mechanisms control these fluctuations. Mammalian rods, like those of toads, generated responses to single photons with trial-to-trial fluctuations 3-4 times smaller than other familiar signals produced by single molecules. We used the properties of the measured fluctuations to constrain models for how the single photon responses are regulated. Neither feedback control of rhodopsin's activity nor saturation within the transduction cascade were consistent with experiment. The measured responses, however, could be explained by multistep shutoff of rhodopsin or a combination of multistep shutoff and saturation.