Guardians of the actin monomer.
Guardians of the actin monomer.
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DOI：
10.1016/j.ejcb.2013.10.012
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发表时间：
2013-10
影响因子：
6.6
通讯作者：
B. Xue;R. Robinson
中科院分区：
文献类型：
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作者：
B. Xue;R. Robinson
肌动蛋白是真核细胞中普遍的力提供者。生物过程利用肌动蛋白聚合产生的压力，通过规定的时间，地点和方向的细丝生长。因此，聚合反应是由严格控制的长丝成核和伸长机械引发和进行的。生物系统通过招募和激活这些机制将力量整合到它们的活动中。为了使肌动蛋白作为一个共同的力量产生聚合马达的功能，细胞必须保持一个积极的，聚合准备单体肌动蛋白池，并尽量减少临时聚合。活性单体肌动蛋白池的维持需要肌动蛋白丝的再循环，通过解聚、核苷酸交换和聚合机制的重新加载，同时单体的水平被不断地监测和补充，当需要时，通过单体储备池的活力获得和通过基因表达。在其单体的生命，肌动蛋白需要保护免受无端成核事件。在这里，我们审查的蛋白质，作为保管人的单体肌动蛋白。我们估计它们的水平在组织规模上，并计算每个肌动蛋白复合物的隐含浓度的基础上报告的结合亲和力。这些估计预测，单体肌动蛋白很少，如果有的话，单独的。因此，守护者控制着肌动蛋白的挥发性，使其爆炸力只在成核和聚合机制的受控环境中释放。
Actin is a universal force provider in eukaryotic cells. Biological processes harness the pressure generated from actin polymerization through dictating the time, place and direction of filament growth. As such, polymerization is initiated and maintainedviatightly controlled filament nucleation and elongation machineries. Biological systems integrate force into their activities through recruiting and activating these machineries. In order that actin function as a common force generating polymerization motor, cells must maintain a pool of active, polymerization-ready monomeric actin, and minimize extemporaneous polymerization. Maintenance of the active monomeric actin pool requires the recycling of actin filaments, through depolymerization, nucleotide exchange and reloading of the polymerization machineries, while the levels of monomers are constantly monitored and supplemented, when needed,viathe access of a reserve pool of monomers and through gene expression. Throughout its monomeric life, actin needs to be protected against gratuitous nucleation events. Here, we review the proteins that act as custodians of monomeric actin. We estimate their levels on a tissue scale, and calculate the implied concentrations of each actin complex based on reported binding affinities. These estimations predict that monomeric actin is rarely, if ever, alone. Thus, the guardians keep the volatility of actin in check, so that its explosive power is only released in the controlled environments of the nucleation and polymerization machineries.