Cantiello H F, Patenaude C, Zaner K
Renal Unit, Massachusetts General Hospital, Boston.
Biophys J. 1991 Jun;59(6):1284-9. doi: 10.1016/S0006-3495(91)82343-8.
Actin filaments, F-actin, a major component of the cortical cytoskeleton, play an important role in a variety of cell functions. In this report we have assessed the role of osmotic stress on the electrochemical properties of F-actin. The spontaneous Donnan potential of a polymerized actin solution (5 mg/ml) was -3.93 +/- 1.84 mV, which was linearly reduced by osmotic stress on the order of 1-20 mOsm (0.28 +/- 0.06 mV/mM). Calculated surface charge density was reduced and eventually reversed by increasing the osmotic stress as expected for a phase transition behavior. The electro-osmotic behavior of F-actin disappeared at pH 5.5 and was dependent on its filamentous nature. Furthermore, osmotically stressed F-actin displayed a nonlinear electric response upon application of electric fields on the order of 500-2,000 V/cm. These data indicate that F-actin in solution may display nonideal electro-osmotic properties consistent with ionic "cable" behavior which may be of biological significance in the processing and conduction of electrical signals within the cellular compartment.
肌动蛋白丝，即F-肌动蛋白，是皮质细胞骨架的主要成分，在多种细胞功能中发挥重要作用。在本报告中，我们评估了渗透应激对F-肌动蛋白电化学性质的作用。聚合肌动蛋白溶液（5毫克/毫升）的自发唐南电位为-3.93±1.84毫伏，在1-20毫渗透摩尔（0.28±0.06毫伏/毫摩尔）量级的渗透应激作用下呈线性降低。正如相变行为所预期的那样，随着渗透应激的增加，计算得到的表面电荷密度降低，最终发生反转。F-肌动蛋白的电渗行为在pH 5.5时消失，且取决于其丝状性质。此外，在施加500-2000伏/厘米量级的电场时，受渗透应激的F-肌动蛋白表现出非线性电响应。这些数据表明，溶液中的F-肌动蛋白可能表现出与离子“电缆”行为一致的非理想电渗性质，这在细胞内电信号的处理和传导中可能具有生物学意义。
