FRAGMIN - A CALCIUM-ION SENSITIVE REGULATORY FACTOR ON THE FORMATION OF ACTIN-FILAMENTS
FRAGMIN - A CALCIUM-ION SENSITIVE REGULATORY FACTOR ON THE FORMATION OF ACTIN-FILAMENTS
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DOI：
10.1021/bi00553a021
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发表时间：
1980-01-01
期刊：
影响因子：
2.9
通讯作者：
HATANO, S
中科院分区：
文献类型：
--
作者：
HASEGAWA, T;TAKAHASHI, S;HATANO, S
多头绒泡菌肌动蛋白先前分离出肌动蛋白和片段蛋白1:1的复合物，片段蛋白是肌动蛋白细丝形成的调节因子。由于fragmin不含半胱氨酸残基，所以用2-硝基-5-硫氰苯甲酸选择性裂解肌动蛋白，然后用柱层析法纯化。Fragmin与actin的分子量几乎相同，但氨基酸组成却大不相同。聚合前将fragmin加入到g -肌动蛋白中，可加速盐诱导的肌动蛋白溶液初始粘度的增加，但使最终粘度远低于正常的f -肌动蛋白。当聚合后加入到f -肌动蛋白中时，fragmin显著降低了肌动蛋白溶液的粘度。在这两种情况下，片段蛋白与肌动蛋白反应的最终产物都是短的f -肌动蛋白丝。随着片段蛋白与肌动蛋白摩尔比的增大，丝的平均长度逐渐减小，且呈指数型分布。当游离Ca2+浓度低于10-7 M时，Fragmin不影响肌动蛋白聚合，也不影响f -肌动蛋白。Ca2+的调控是可逆的。
Physarum polycephalum actinin previously isolated a 1:1 complex of actin and fragmin which is a regulatory factor in the formation of actin filaments. Since fragmin did not contain a cysteine residue, it was purified from the complex by the selective cleavage of actin with 2-nitro-5-thiocyanobenzoic acid, followed by column chromatography. Fragmin had nearly the same MW as actin, but had a quite different amino acid composition. When added to G-actin before polymerization, fragmin accelerated the initial viscosity increase of actin solutions induced by salts, but kept the final viscosity much lower than normal F-actin. When added to F-actin after polymerization, fragmin drastically reduced the viscosity of actin solutions. In both cases, the final products of reaction of fragmin with actin were short F-actin filaments. The number average length of the filaments decreased with the increasing molar ratio of fragmin to actin, and the length distribution was always exponential. Fragmin required for its activity a concentration of free Ca2+ higher than 10-6 M. When the concentration of free Ca2+ was lower than 10-7 M, fragmin affected neither actin polymerization nor F-actin. The regulation by Ca2+ was reversible.