THEORETICAL-MODEL FOR THE COOPERATIVE EQUILIBRIUM BINDING OF MYOSIN SUBFRAGMENT-1 TO THE ACTIN-TROPONIN-TROPOMYOSIN COMPLEX
THEORETICAL-MODEL FOR THE COOPERATIVE EQUILIBRIUM BINDING OF MYOSIN SUBFRAGMENT-1 TO THE ACTIN-TROPONIN-TROPOMYOSIN COMPLEX
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DOI：
10.1073/pnas.77.6.3186
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发表时间：
1980-01-01
期刊：
影响因子：
--
通讯作者：
GREENE, L
中科院分区：
文献类型：
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作者：
HILL, TL;EISENBERG, E;GREENE, L
用线性伊辛模型分析了肌球蛋白亚片段1(S-1)在钙离子存在和不存在的情况下与调节肌动蛋白细丝平衡结合的最新实验数据。在该模型中，原肌球蛋白-肌钙蛋白单位(包括肌动蛋白细丝上的7个位点)可以处于两种可能状态中的一种，这两种状态对S-1具有不同的固有自由能和不同的结合常数。结合的S-1分子之间不相互作用。在这些单元之间存在最近邻(对)相互作用，这取决于对中每个成员的状态和与对中1个成员结合的钙离子的数量。在这个系统中有两个正的协作性来源：作为一个单一单元的一部分，7个肌动蛋白位点一起改变状态的事实；以及单元之间存在有吸引力的最近邻相互作用。模型中的参数是通过对数据进行拟合来评估的，无论是在存在还是在没有钙离子的情况下。讨论了该模型的几个扩展。
Recent experimental data on the equilibrium binding of myosin subfragment 1 (S-1) to regulated actin filaments in the presence and in the absence of Ca2+ are analyzed by using a linear Ising model. In the model, each tropomyosin-troponin unit (including 7 sites on the actin filament) can be in 1 of 2 possible states, which have different intrinsic free energies and different binding constants for S-1. Bound S-1 molecules do not interact with each other. There are nearest-neighbor (pair) interactions between these units that depend on the state of each member of the pair and on the number of Ca2+ bound to 1 member of the pair. There are 2 sources of positive cooperativity in this system: the fact that 7 actin sites change state together as part of a single unit; and the existence of attractive nearest-neighbor interactions between units. Parameters in the model are evaluated by fitting the data, both in the presence and in the absence of Ca2+. Several extensions of this model are discussed.