The first step in the polymerisation of actin.
The first step in the polymerisation of actin.
复制标题
肌动蛋白聚合的第一步。
DOI：
10.1111/j.1432-1033.1981.tb05302.x
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发表时间：
1981
期刊：
影响因子：
--
通讯作者：
F. Travers
中科院分区：
文献类型：
--
作者：
J. Rouayrenc;F. Travers
在某些阳离子（如K+或Mg 2+）的存在下，肌动蛋白聚合。在一定浓度（临界浓度）以下，单体G-肌动蛋白不受K+或Mg ~（2+）的影响。然而，Rich和Estes的蛋白水解实验[J. Mol. Biol. Biol.104，777- 792（1976）]强烈地表明阳离子诱导G-肌动蛋白构象的变化，导致肌动蛋白的新形式，G*-肌动蛋白。这种构象变化可能是肌动蛋白聚合的第一步。本文用差示光谱法研究了K ~+诱导的G ~*-肌动蛋白。我们表明，G*-肌动蛋白是一个单体，我们确认，结合ATP不裂解。我们还研究了G-肌动蛋白在平衡与G*-肌动蛋白平衡在4 ℃作为K+或Mg 2+浓度的函数。对于KCl，转化可以解释为筛选效应。Mg 2+的作用更具特异性，G-肌动蛋白的构象变化可能是由两个或三个Mg 2+离子/分子的结合引起的。我们认为，G-肌动蛋白与G*-肌动蛋白转化平衡的结果从肌动蛋白表面上的聚阴离子区域的中和，这个区域可能是高度带负电荷的N端。
In the presence of certain cations (e.g. K+ or Mg2+) actin polymerizes. Below a certain concentration (the critical concentration) the monomer G-actin does not polymerize on the addition of K+ or Mg2+. However, the proteolysis experiments of Rich and Estes [J. Mol. Biol. 104, 777--792 (1976)] strongly suggest that cations induce a change in conformation of G-actin leading to a novel form of actin, G*-actin. This conformational change may be the first step in the polymerization of actin. We have studied G*-actin induced by K+, by difference spectroscopy. We show that G*-actin is a monomer and we confirm that the bound ATP is not cleaved. We also studied the G-actin in equilibrium with G*-actin equilibrium at 4 degrees C as a function of K+ or Mg2+ concentration. With KCl, the transformation can be accounted for as a screening effect. The effect of Mg2+ is more specific and the change in conformation of the G-actin could result from the binding of two or three Mg2+ ions/molecule. We suggest that the G-actin in equilibrium with G*-actin transformation results from the neutralization of a polyanionic region on the actin surface and that this region could be the highly negatively charged N terminus.