Self diffusion of interacting membrane proteins.
Self diffusion of interacting membrane proteins.
复制标题
相互作用的膜蛋白的自扩散。
DOI：
10.1016/s0006-3495(89)82882-6
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发表时间：
1989
影响因子：
3.4
通讯作者：
Owicki,JC
中科院分区：
文献类型：
--
作者：
Abney,JR;Scalettar,BA;Owicki,JC
用二维广义Smoluchowski方程分析了浓缩膜系统中相互作用的膜蛋白随时间(或距离)的自扩散。这个方程为描述通过直接作用力和流体动力相互作用的粒子的扩散提供了一个很好的起点；在这项初步工作中，只明确考虑了直接相互作用的影响。给出了描述存在硬核排斥、软排斥和弱吸引的软排斥时的扩散的数据。还计算了相互作用对来自小鼠肝脏缝隙连接的真实蛋白质分子的自扩散系数的影响。结果表明，自扩散总是受到直接相互作用的抑制；这一观察结果被解释为在有限的蛋白质浓度下将存在的笼子。还需要注意的是，在很小的距离尺度上，扩散系数完全由非常强的布朗力决定；因此，作为位移的函数，自扩散系数从无限稀释时的值迅速衰减到其稳态相互作用平均值。稳态自扩散系数描述了从大约10纳米到细胞尺寸的距离尺度上的运动，是在光漂白实验后的荧光恢复中测量到的量。扩散系数的短程行为在粒子间距离尺度上很重要，因此可能会影响最近邻碰撞过程发生的速率。本文给出的硬盘理论结果与其他工作人员得到的格子蒙特卡罗结果符合得很好。实验测得的抗体-半抗原复合体结合到膜表面的扩散系数的浓度依赖关系与理论预测的一致。整体膜蛋白的实验扩散系数的变化比理论预测的要大，也可能反映了蛋白质对膜粘度的扰动。
A two-dimensional version of the generalized Smoluchowski equation is used to analyze the time (or distance) dependent self diffusion of interacting membrane proteins in concentrated membrane systems. This equation provides a well established starting point for descriptions of the diffusion of particles that interact through both direct and hydrodynamic forces; in this initial work only the effects of direct interactions are explicitly considered. Data describing diffusion in the presence of hard-core repulsions, soft repulsions, and soft repulsions with weak attractions are presented. The effect that interactions have on the self-diffusion coefficient of a real protein molecule from mouse liver gap junctions is also calculated. The results indicate that self diffusion is always inhibited by direct interactions; this observation is interpreted in terms of the caging that will exist at finite protein concentration. It is also noted that, over small distance scales, the diffusion coefficient is determined entirely by the very strong Brownian forces; therefore, as a function of displacement the self-diffusion coefficient decays (rapidly) from its value at infinite dilution to its steady-state interaction-averaged value. The steady-state self-diffusion coefficient describes motion over distance scales that range from approximately 10 nm to cellular dimensions and is the quantity measured in fluorescence recovery after photobleaching experiments. The short-ranged behavior of the diffusion coefficient is important on the interparticle-distance scale and may therefore influence the rate at which nearest-neighbor collisional processes take place. The hard-disk theoretical results presented here are in excellent agreement with lattice Monte-Carlo results obtained by other workers. The concentration dependence of experimentally measured diffusion coefficients of antibody-hapten complexes bound to the membrane surface is consistent with that predicted by the theory. The variation in experimental diffusion coefficients of integral membrane proteins is greater than that predicted by the theory, and may also reflect protein-induced perturbations in membrane viscosity.