Diffusion of protein receptors on a cylindrical dendritic membrane with partially absorbing traps
Diffusion of protein receptors on a cylindrical dendritic membrane with partially absorbing traps
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DOI：
10.1137/070698373
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发表时间：
2008-01-01
影响因子：
1.9
通讯作者：
Ward, Michael J.
中科院分区：
文献类型：
--
作者：
Bressloff, Paul C.;Earnshaw, Berton A.;Ward, Michael J.
我们提出了一个蛋白质受体在圆柱形树突膜内运输的模型，该树突包含称为棘突的小突起。脊椎是中枢神经系统中大多数兴奋性突触的位置，是树突膜内扩散的受体的局部陷阱。我们将棘突和树突的横向交叉点视为空间扩展的部分吸收边界，并使用奇异微扰理论来分析受体的稳态分布。我们将奇异摄动解与完整模型的数值解和一维简化模型的解进行了比较，发现它们之间有很好的一致性。我们还从我们的模型中导出了Fokker-Planck方程组，并用它精确地求解了单个受体沿树枝沿固定的轴向距离行进的平均首次通过时间(MFPT)问题。然后，这被用来计算当刺沿电缆长度均匀分布时受体的有效扩散系数，并显示刺的不均匀分布如何引起异常的次扩散。
We present a model of protein receptor trafficking within the membrane of a cylindrical dendrite containing small protrusions called spines. Spines are the locus of most excitatory synapses in the central nervous system and act as localized traps for receptors diffusing within the dendritic membrane. We treat the transverse intersection of a spine and dendrite as a spatially extended, partially absorbing boundary and use singular perturbation theory to analyze the steady-state distribution of receptors. We compare the singular perturbation solutions with numerical solutions of the full model and with solutions of a reduced one-dimensional model and find good agreement between them all. We also derive a system of Fokker-Planck equations from our model and use it to exactly solve a mean first passage time (MFPT) problem for a single receptor traveling a fixed axial distance along the dendrite. This is then used to calculate an effective diffusion coefficient for receptors when spines are uniformly distributed along the length of the cable and to show how a nonuniform distribution of spines gives rise to anomalous subdiffusion.