EFFECT OF FRAGMIN ON ACTIN POLYMERIZATION - EVIDENCE FOR ENHANCEMENT OF NUCLEATION AND CAPPING OF THE BARBED END
EFFECT OF FRAGMIN ON ACTIN POLYMERIZATION - EVIDENCE FOR ENHANCEMENT OF NUCLEATION AND CAPPING OF THE BARBED END
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DOI：
10.1002/cm.970020505
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发表时间：
1982-01-01
影响因子：
--
通讯作者：
HATANO, S
中科院分区：
文献类型：
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作者：
SUGINO, H;HATANO, S
分离自绒泡菌（Physarum plasmodia）的Fragmin在Ca ~（2+）存在下限制肌动蛋白聚合产生短的F-肌动蛋白丝。当肌动蛋白在低浓度的盐中聚合时，fragmin增加了肌动蛋白聚合的临界浓度。这种影响的fragmin的临界浓度是独立的fragmin肌动蛋白的摩尔比。肌动蛋白单体添加到重的裂肌球蛋白修饰的F-肌动蛋白片段与fragmin处理单向发生在每个片段的尖端。法安明显然结合到F-肌动蛋白丝的倒刺末端，并抑制肌动蛋白单体在此末端的结合和解离。Fragmin加速肌动蛋白聚合的初始阶段。当在存在少量fragmin的情况下使恒定量的G-肌动蛋白聚合时，半聚合时间的倒数与所添加的fragmin的量的平方根成比例地增加。这意味着，片段蛋白作为一个有效的促进剂的成核步骤中肌动蛋白聚合。这两个功能的fragmin，促进成核和封盖在倒刺的F-肌动蛋白的结束，需要微摩尔浓度的Ca 2+。
Fragmin isolated from Physarum plasmodia restricts the polymerization of actin to produce short F-actin filaments in the presence of Ca2+. When actin is polymerized at low concentrations of salts, fragmin increases the critical concentration of actin for polymerization. This effect of fragmin on the critical concentration is independent of the molar ratio of fragmin to actin. The addition of actin monomers onto heavy meromyosin-decorated F-actin fragments treated with fragmin occurs unidirectionally at the pointed end of each fragment. Fragmin apparently binds to the barbed ends of F-actin filaments, and inhibits association and dissociation of actin monomers at this end. Fragmin accelerates the initial stage of polymerization of actin. When a constant amount of G-actin is polymerized in the presence of small amounts of fragmin, the inverse of the half-polymerization time increases in proportion to the square root of the amount of fragmin added. This means that fragmin acts as a potent promoter of the nucleation step in actin polymerization. Both functions of fragmin, promotion of nucleation and capping at the barbed end of F-actin, require micromolar concentrations of Ca2+.