Myosin subfragment 1 binding to relaxed actin filaments and steric model of relaxation.
Myosin subfragment 1 binding to relaxed actin filaments and steric model of relaxation.
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肌球蛋白亚片段 1 与松弛的肌动蛋白丝和松弛的空间模型结合。
DOI：
10.1021/bi00506a030
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发表时间：
1981
期刊：
影响因子：
2.9
通讯作者：
Knox,MK
中科院分区：
文献类型：
--
作者：
Murray,JM;Weber,A;Knox,MK
John M. Murray，Annemarie Weber，* and玛丽K. Knox摘要：人们普遍认为，脊椎动物骨骼肌的松弛是肌钙蛋白-原肌球蛋白空间阻滞肌球蛋白附着的结果。因此，我们确定了在何种程度上肌动蛋白结合的核苷酸游离肌球蛋白亚片段1和肌动蛋白结合的亚片段1含有腺苷三磷酸（ATP）类似物β，-亚氨基-ATP（AMPPNP）被抑制时，肌钙蛋白-原肌球蛋白-肌动蛋白丝处于松弛状态。维持松弛状态除了需要去除钙离子外，还需要很低的亚片段1与肌动蛋白的比例，因为肌球蛋白对肌动蛋白丝的饱和会逆转缺乏钙离子时的松弛。我们观察到，当肌动蛋白丝松弛时，两个亚片段物种的肌动蛋白结合受到不同程度的抑制。这些数据进行了分析，在两个不同的assumptions，模型1和模型2的松弛的立体模型。根据模型1，这代表了竞争性抑制的经典情况，肌动蛋白上的S1结合位点被肌钙蛋白-原肌球蛋白或S1占据，但从来没有同时被两者占据。S1-actin结合常数不受钙离子迁移的影响。根据模型1，两种S1物质中的每一种的结合位点必须是不同的且不重叠的，使得在松弛状态下肌钙蛋白-原肌球蛋白阻断无核苷酸位点的比例大于含有S1的AMPPNP。根据模型2，肌钙蛋白-原肌球蛋白在没有钙的情况下总是与所有的S1结合位点结合，但它仅部分地占据它们。因此，每个结合位点可以同时含有原肌球蛋白和S1。由于在松弛过程中只有部分结合位点可用于Sl，Sl-肌动蛋白结合常数降低，而可接近位点的数量与松弛过程中相同。
John M. Murray, Annemarie Weber,* and Mary K. Knox abstract: It is widely assumed that relaxation of vertebrate skeletal muscle is the result of steric blockage of myosin at-tachment by troponin-tropomyosin. Therefore, we determined to what extent actin binding of nucleotide-free myosin sub-fragment 1 and actinbinding of subfragment 1 containing the adenosine triphosphate (ATP) analogue ß,-imido-ATP (AMPPNP) was inhibited when troponin-tropomyosin-actin filaments were in the relaxed state. Maintaining the relaxed state requires, in addition to calcium removal, a very low ratio of subfragment 1 to actin because saturation of the actin filament with myosin reverses relaxation in theabsence of calcium. We observed that actin binding of the two sub-fragment species was inhibited to a different extentwhen the actin filaments were relaxed. These data are analyzed in terms of the steric model of relaxationunder two different as-sumptions, model 1 and model 2. According to model 1, which represents the classical case of competitive inhibition, the Sl binding site on actin is occupied either by troponin-tropo-myosin or by Sl, but never by both simultaneously. TheSl-actin binding constants are not altered by calcium re-moval. In terms of model 1 the binding sites for each of the two Sl species must be different and nonoverlapping so that in the relaxed state troponin-tropomyosin blocks a larger fraction of the sites for nucleotide-free than for AMPPNP containing Sl. According to model 2, troponin-tropomyosin in the absence of calcium is bound to all Sl binding sites at all times, but it occupies them only partially. Each binding site, therefore, can contain both tropomyosin and Sl at the same time. With only part of the binding site available to Sl during relaxation, the Sl-actin binding constants are lowered while the number of accessible sites is the same as in the
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影响因子：
2.9
作者：
Estes,PA;Suba,EJ;Lawler-Heavner,J;Elashry-Stowers,D;Wei,LL;Toft,DO;Sullivan,WP;Horwitz,KB;Edwards,DP
通讯作者：
Edwards,DP
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影响因子：
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作者：
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影响因子：
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作者：
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通讯作者：
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影响因子：
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作者：
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DOI：
10.1073/pnas.80.10.2854
发表时间：
1983
影响因子：
11.1
作者：
C. Radanyi;I. Joab;J. Renoir;H. Richard;E. Baulieu
通讯作者：
E. Baulieu