Bressloff Paul C, Earnshaw Berton A
Department of Mathematics, University of Utah, Salt Lake City, Utah, USA.
Biophys J. 2009 Mar 4;96(5):1786-802. doi: 10.1016/j.bpj.2008.12.3889.
The postsynaptic density (PSD) is a cytoskeletal specialization within the postsynaptic membrane of a neuron that helps to concentrate and organize neurotransmitter receptors at a chemical synapse. The total number of receptors within the PSD, which is a major factor in determining the physiological strength or weight of a synapse, fluctuates due to the surface diffusion of receptors into and out of the PSD, and the interactions of receptors with scaffolding proteins and cytoskeletal elements within the PSD. In this article, we present a stochastic model of protein receptor trafficking at the PSD that takes into account these various processes. The PSD is treated as a stochastically gated corral, which contributes a source of extrinsic or environmental noise that supplements the intrinsic noise arising from small receptor numbers. Using a combination of stochastic analysis and Monte Carlo simulations, we determine the time-dependent variation in the mean and variance of synaptic receptor numbers for a variety of initial conditions that simulate fluorescence recovery after photobleaching experiments, and indicate how such data might be used to infer certain properties of the PSD.
突触后致密区（PSD）是神经元突触后膜内的一种细胞骨架特化结构，有助于在化学突触处聚集和组织神经递质受体。PSD内受体的总数是决定突触生理强度或权重的一个主要因素，由于受体进出PSD的表面扩散以及受体与PSD内支架蛋白和细胞骨架成分的相互作用，其数量会发生波动。在本文中，我们提出了一个PSD处蛋白质受体运输的随机模型，该模型考虑了这些不同的过程。PSD被视为一个随机门控的围栏，它提供了一种外在或环境噪声源，补充了因受体数量少而产生的内在噪声。通过结合随机分析和蒙特卡罗模拟，我们确定了在各种初始条件下突触受体数量均值和方差随时间的变化，这些初始条件模拟了光漂白实验后的荧光恢复，并指出了如何利用这些数据推断PSD的某些特性。
