Fung B M, Eyob E
Arch Biochem Biophys. 1983 Feb 1;220(2):370-8. doi: 10.1016/0003-9861(83)90426-5.
It was found that the rate of polymerization of G-actin increased with the decrease of ATP concentration. When excess ATP was replaced by chloride through anion-exchange treatment, the extent of actin polymerization did not change provided that the ionic strength was raised immediately after the treatment. In the meantime, the rate of actin polymerization was greatly enhanced after the removal of excess ATP. The rate enhancement was much less when both excess Ca2+ and excess ATP were removed. G-actin with excess ATP replaced by chloride had larger light scattering and showed a "catalytic" effect on the polymerization of normal G-actin. The inhibition of actin polymerization by cytochalasin B in 100 mM KCl was much more obvious for G-actin with excess ATP removed than for normal G-actin. It is suggested that the reduction of excess ATP concentration in a G-actin solution increases the binding of weak-affinity Ca2+ and promotes the formation of oligomeric actin (actin nuclei).
研究发现，G-肌动蛋白的聚合速率随ATP浓度的降低而增加。当通过阴离子交换处理用氯离子取代过量的ATP时，只要处理后立即提高离子强度，肌动蛋白的聚合程度就不会改变。同时，去除过量的ATP后，肌动蛋白的聚合速率大大提高。当同时去除过量的Ca2+和过量的ATP时，速率提高幅度要小得多。用氯离子取代过量ATP的G-肌动蛋白具有更大的光散射，并且对正常G-肌动蛋白的聚合表现出“催化”作用。在100 mM KCl中，细胞松弛素B对去除过量ATP的G-肌动蛋白的肌动蛋白聚合抑制作用比对正常G-肌动蛋白更为明显。这表明，G-肌动蛋白溶液中过量ATP浓度的降低会增加弱亲和力Ca2+的结合，并促进寡聚肌动蛋白（肌动蛋白核）的形成。
