Constrained diffusion or immobile fraction on cell surfaces: A new interpretation
Constrained diffusion or immobile fraction on cell surfaces: A new interpretation
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DOI：
10.1016/s0006-3495(96)79846-6
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发表时间：
1996-06-01
影响因子：
3.4
通讯作者：
Webb, WW
中科院分区：
文献类型：
--
作者：
Feder, TJ;BrustMascher, I;Webb, WW
蛋白质在细胞膜中的横向迁移率通常使用荧光光漂白恢复（FPR）来测量。由于这种技术的发展，数据已被解释为假设自由布朗扩散的细胞表面受体在两个维度上，一个解释，需要一个子集的扩散物种保持不动。这种所谓的不动部分的起源仍然是一个谜。在FPR中，数千个粒子的运动本质上是平均的，不可避免地掩盖了单个运动的细节。最近，对单个细胞表面受体的跟踪已经确定了几种不同类型的运动（Gross和Webb，1988; Ghosh和Webb，1988，1990，1994; Kusumi等人，1993; Qian等人，1991; Slattery，1995），从而质疑FPR数据作为有限移动的分数的自由布朗运动的经典解释，我们已经测量了运动的荧光标记的免疫球蛋白E复合高亲和力受体（Fc（γ）RI）对大鼠嗜碱性白血病细胞使用单粒子跟踪和FPR。在以前的研究中，我们的跟踪结果表明，个别受体可以自由扩散，或可能表现出限制，时间依赖性（异常）扩散。因此，我们已经分析了FPR数据的一个新的模型，以考虑到这种变化的运动，我们表明，不动的部分可能是由于粒子移动与异常subdiffusion与限制横向流动性，异常subdiffusion表示随机分子运动中的均方位移增长作为一个幂律的时间与分数的正指数小于1。这些发现需要一种新的细胞膜结构模型。
Protein lateral mobility in cell membranes is generally measured using fluorescence photobleaching recovery (FPR). Since the development of this technique, the data have been interpreted by assuming free Brownian diffusion of cell surface receptors in two dimensions, an interpretation that requires that a subset of the diffusing species remains immobile. The origin of this so-called immobile fraction remains a mystery. In FPR, the motions of thousands of particles are inherently averaged, inevitably masking the details of individual motions. Recently, tracking of individual cell surface receptors has identified several distinct types of motion (Gross and Webb, 1988; Ghosh and Webb, 1988, 1990, 1994; Kusumi et al. 1993; Qian et al. 1991; Slattery, 1995), thereby calling into question the classical interpretation of FPR data as free Brownian motion of a limited mobile fraction, We have measured the motion of fluorescently labeled immunoglobulin E complexed to high affinity receptors (Fc(epsilon)RI) on rat basophilic leukemia cells using both single particle tracking and FPR. As in previous studies, our tracking results show that individual receptors may diffuse freely, or may exhibit restricted, time-dependent (anomalous) diffusion. Accordingly, we have analyzed FPR data by a new model to take this varied motion into account, and we show that the immobile fraction may be due to particles moving with the anomalous subdiffusion associated with restricted lateral mobility, Anomalous subdiffusion denotes random molecular motion in which the mean square displacements grow as a power law in time with a fractional positive exponent less than one. These findings call for a new model of cell membrane structure.