Keratin intermediate filaments form dynamic intracellular networks, which span the entire cytoplasm and provide mechanical strength to the cell. The mechanical resilience of the keratin intermediate filament network itself is determined by filament bundling. The bundling process can be reproduced in artificial conditions in the absence of any specific cross-linking proteins, which suggests that it is driven by generic physical forces acting between filaments. Here, we suggest a detailed model for bundling of keratin intermediate filaments based on interfilament electrostatic and hydrophobic interactions. It predicts that the process is limited by an optimal bundle thickness, which is determined by the electric charge of the filaments, the number of hydrophobic residues in the constituent keratin polypeptides, and the extent to which the electrolyte ions are excluded from the bundle interior. We evaluate the kinetics of the bundling process by considering the energy barrier a filament has to overcome for joining a bundle.

中文翻译：

---

角蛋白中间丝的捆绑模型

角蛋白中间丝形成动态的细胞内网络，跨越整个细胞质并为细胞提供机械强度。角蛋白中间丝网络本身的机械弹性由丝束决定。在没有任何特定交联蛋白的情况下，可以在人工条件下复制捆绑过程，这表明它是由作用于细丝之间的一般物理力驱动的。在这里，我们提出了一个基于丝间静电和疏水相互作用的角蛋白中间丝捆绑的详细模型。它预测该过程受到最佳束厚度的限制，该厚度由细丝的电荷、组成角蛋白多肽中疏水残基的数量决定，以及电解质离子从束内部排除的程度。我们通过考虑长丝必须克服的能量障碍来评估捆绑过程的动力学。