Maruyama K, Hartwig J H, Stossel T P
Biochim Biophys Acta. 1980 Dec 16;626(2):494-500.
Cytochalasin B decreased the flow birefringence and s20,w and increased the extinction angle of actin filaments in salt solutions favoring polymerization of the protein. These changes occurred without a detectable increase in the equilibrium actin monomer concentration determined by a radioassay. These results complement earlier observations indicating that cytochalasin B shortens actin filaments without net depolymerization. Analyzed in terms of Flory's classical network theory, this shortening accounts for the marked effect of cytochalasin B in dissolving the gel structure of F-actin crosslinked by actin-binding protein concentrations near the critical concentration for incipient gelation. Cytochalasin B decreased the annealing rate of low concentrations of actin filament fragments prepared by sonic disruption. The result is consistent with the idea that cytochalasin B binds to the ends of actin filaments, and may explain how cytochalasin B causes filament shortening.
细胞松弛素B降低了流动双折射和沉降系数s20,w，并增大了肌动蛋白丝在有利于蛋白质聚合的盐溶液中的消光角。这些变化发生时，通过放射性测定法测定的平衡肌动蛋白单体浓度并未出现可检测到的增加。这些结果补充了早期的观察结果，表明细胞松弛素B缩短了肌动蛋白丝而没有净解聚。根据弗洛里经典网络理论分析，这种缩短解释了细胞松弛素B在溶解由接近初始凝胶化临界浓度的肌动蛋白结合蛋白浓度交联的F-肌动蛋白凝胶结构方面的显著作用。细胞松弛素B降低了通过超声破碎制备的低浓度肌动蛋白丝片段的退火速率。该结果与细胞松弛素B结合到肌动蛋白丝末端的观点一致，并且可以解释细胞松弛素B如何导致丝缩短。
