The Channel Capacity of Channelrhodopsin and Other Intensity-Driven Signal Transduction Receptors
The Channel Capacity of Channelrhodopsin and Other Intensity-Driven Signal Transduction Receptors
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DOI：
10.1109/tmbmc.2019.2895790
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发表时间：
2018-04
期刊：
影响因子：
--
通讯作者：
A. Eckford;P. Thomas
中科院分区：
文献类型：
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作者：
A. Eckford;P. Thomas
生物系统通过无数的途径从周围环境转换信号。在本文中，我们将信号转导描述为一个通信系统：信号转导受体充当该系统中的接收器，并且可以建模为有限状态马尔可夫链，其转换率由输入信号控制。使用这个通用模型，我们给出离散时间内独立同分布（IID）输入下的互信息，并获得连续时间限制内的互信息。我们证明互信息具有简洁的封闭式表达，具有明确的物理意义。我们还给出了通过 IID 输入实现香农容量的充分条件。我们用三个例子来说明我们的结果：1) 光门控视紫红质通道 2 (ChR2) 受体； 2) 配体门控烟碱乙酰胆碱受体； 3) 配体门控钙调蛋白受体。特别是，我们表明 ChR2 受体的 IID 容量等于其 Shannon 容量。最后，我们讨论如果只能观察到每个状态的某些属性（例如离子通道是打开还是关闭），结果会如何变化。
Biological systems transduce signals from their surroundings through a myriad of pathways. In this paper, we describe signal transduction as a communication system: the signal transduction receptor acts as the receiver in this system, and can be modeled as a finite-state Markov chain with transition rates governed by the input signal. Using this general model, we give the mutual information under independent, identically distributed (IID) inputs in discrete time, and obtain the mutual information in the continuous-time limit. We show that the mutual information has a concise closed-form expression with clear physical significance. We also give a sufficient condition under which the Shannon capacity is achieved with IID inputs. We illustrate our results with three examples: 1) the light-gated Channelrhodopsin-2 (ChR2) receptor; 2) the ligand-gated nicotinic acetylcholine receptor; and 3) the ligand-gated calmodulin receptor. In particular, we show that the IID capacity of the ChR2 receptor is equal to its Shannon capacity. We finally discuss how the results change if only certain properties of each state can be observed, such as whether an ion channel is open or closed.