Department of Applied Mathematics, University of Washington, Seattle, WA 98195, USA.
IEEE Trans Nanobioscience. 2012 Sep;11(3):289-95. doi: 10.1109/TNB.2011.2182658. Epub 2012 Feb 10.
Signal transduction, the information processing mechanism in biological cells, is carried out by a network of biochemical reactions. The dynamics of driven biochemical reactions can be studied in terms of nonequilibrium statistical physics. Such systems may also be studied in terms of Shannon's information theory. We combine these two perspectives in this study of the basic units (modules) of cellular signaling: the phosphorylation dephosphorylation cycle (PdPC) and the guanosine triphosphatase (GTPase). We show that the channel capacity is zero if and only if the free energy expenditure of biochemical system is zero. In fact, a positive correlation between the channel capacity and free energy expenditure is observed. In terms of the information theory, a linear signaling cascade consisting of multiple steps of PdPC can function as a distributed "multistage code." With increasing number of steps in the cascade, the system trades channel capacity with the code complexity. Our analysis shows that while a static code can be molecular structure based, a biochemical communication channel has to have energy expenditure.
信号转导是生物细胞中的信息处理机制，它是通过一系列生化反应网络来实现的。受驱动力作用的生化反应的动力学可以用非平衡统计物理来研究。这样的系统也可以用香农信息论来研究。在这项对细胞信号的基本单元（模块）的研究中，我们结合了这两种观点：磷酸化去磷酸化循环（PdPC）和鸟苷三磷酸酶（GTPase）。我们表明，如果生化系统的自由能消耗为零，则信道容量为零。事实上，我们观察到信道容量与自由能消耗之间存在正相关关系。从信息论的角度来看，由多个 PdPC 步骤组成的线性信号级联可以作为分布式“多级码”发挥作用。随着级联中步骤的增加，系统会在信道容量和代码复杂性之间进行权衡。我们的分析表明，虽然静态代码可以基于分子结构，但生化通信信道必须有能量消耗。
