An important function of microRNAs in gene regulation is to repress the protein synthesis in a multi-step process with implications in timing efficiency of the regulatory network. We propose a stochastic description of translation-initiation mechanism and solve for the steady state distribution of protein number in the linear regime. The time-dependent moments have been approximately calculated and the role of miRNAs in determining the First Passage Time (FPT) properties of protein dynamics has been established. We analytically show that the modulation of slow rates of the translation process will result in efficient and robust timing mechanism. For a general nonlinear model our numerical simulation results are in qualitative agreement with the linear model.

microRNA 在基因调控中的一个重要功能是抑制多步骤过程中的蛋白质合成，这对调控网络的计时效率有影响。我们提出了翻译启动机制的随机描述，并解决了线性区域中蛋白质数量的稳态分布。已经近似计算了时间依赖矩，并且已经确定了 miRNA 在确定蛋白质动力学的首次通过时间 (FPT) 特性中的作用。我们分析表明，对翻译过程的慢速进行调制将导致有效和稳健的计时机制。对于一般非线性模型，我们的数值模拟结果与线性模型定性一致。