Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois, USA
Biophys J. 2011 Oct 5;101(7):1597-603. doi: 10.1016/j.bpj.2011.08.033.
We develop a computational model to compare the relative importance of unbinding and unfolding of actin cross-linking proteins (ACPs) in the dynamic properties of the actin cytoskeleton. We show that in the strain-stiffening regime with typical physiological and experimental strain rates, unbinding events are predominant with negligible unfolding. ACPs unbound by greater forces experience larger displacements, with a tendency to rebind to different filaments. At constant strain, stress relaxes to physiological levels by unbinding only--not unfolding--of ACPs, which is consistent with experiments. Also, rebinding of ACPs dampens full relaxation of stress. When the network is allowed to return to a stress-free state after shear deformation, plastic deformation is observed only with unbinding. These results suggest that despite the possibility of unfolding, unbinding of ACPs is the major determinant for the rheology of the actin network.
我们开发了一个计算模型，以比较肌动蛋白交联蛋白（ACPs）的解联和展开在肌动球蛋白细胞骨架动力学性质中的相对重要性。我们表明，在具有典型生理和实验应变率的应变硬化区，解联事件占主导地位，展开可忽略不计。由更大力解联的 ACPs 经历更大的位移，并且倾向于重新结合到不同的细丝上。在恒定应变下，仅通过 ACPs 的解联而不是展开，应力松弛到生理水平，这与实验一致。此外，ACPs 的重新结合会抑制应力的完全松弛。当网络在剪切变形后被允许返回到无应力状态时，仅在解联时才观察到塑性变形。这些结果表明，尽管存在展开的可能性，但 ACPs 的解联是肌动球蛋白网络流变学的主要决定因素。
