We analyze the structure of the cytoplasm by performing single-molecule displacement mapping on a diverse set of native cytoplasmic proteins in exponentially growing Escherichia coli . We evaluate the method for application in small compartments and find that confining effects of the cell membrane affect the diffusion maps. Our analysis reveals that protein diffusion at the poles is consistently slower than in the center of the cell, i.e., to an extent greater than the confining effect of the cell membrane. We also show that the diffusion coefficient scales with the mass of the used probes, taking into account the oligomeric state of the proteins, while parameters such as native protein abundance or the number of protein-protein interactions do not correlate with the mobility of the proteins. We argue that our data paint the prokaryotic cytoplasm as a compartment with subdomains in which the diffusion of macromolecules changes with the perceived viscosity.

中文翻译：

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大肠杆菌细胞质中的蛋白质扩散与复合物的质量成比例并且依赖于位置

我们通过对呈指数增长的多种天然细胞质蛋白进行单分子位移映射来分析细胞质的结构大肠杆菌. 我们评估了在小隔间中应用的方法，发现细胞膜的限制效应会影响扩散图。我们的分析表明，两极的蛋白质扩散始终比细胞中心的扩散慢，即扩散程度大于细胞膜的限制效应。我们还表明，考虑到蛋白质的寡聚状态，扩散系数与所用探针的质量成比例，而天然蛋白质丰度或蛋白质-蛋白质相互作用的数量等参数与蛋白质的流动性无关. 我们认为我们的数据将原核细胞质描绘成一个带有子域的隔间，其中大分子的扩散随着感知粘度的变化而变化。