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首页> 外文期刊>Journal of Molecular Biology >Specialized conservation of surface loops of myosin: evidence that loops are involved in determining functional characteristics.
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Specialized conservation of surface loops of myosin: evidence that loops are involved in determining functional characteristics.

机译：肌球蛋白表面环的专门保护：环参与确定功能特征的证据。

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摘要

The molecular motor myosin has been the focus of considerable structure-function analysis. Of key interest are the portions of the protein that control the rate of ATP hydrolysis, the affinity for actin, and the velocity at which myosin moves actin. Two regions that have been implicated in determining these parameters are the "loop" regions at the junctions of the 25 kDa and 50 kDa domains and the 50 kDa and 20 kDa domains of the protein. However, the sequences of these regions are poorly conserved between different myosin families, suggesting that they are not constrained evolutionarily, and thus are relatively unimportant for myosin function. In order to address this apparent incongruity, we have performed an analysis of relative rates of observed evolutionary change. We found that the sequences of these loop regions appear to be actually more constrained than the sequences of the rest of the myosin molecule, when myosins are compared that are known to be kinetically or developmentally similar. This suggests that these loop regions could play an important role in myosin function and supports the idea that they are involved in modulating the specific kinetic characteristics that functionally differentiate one myosin isoform from another. Apparently "unconserved" loops may generally play a role in determining kinetic properties of enzymes, and similar analyses of relative rates of evolution may prove useful for the study of structure-function relationships in other protein families. Copyright 1999 Academic Press.
机译：分子运动肌球蛋白一直是大量结构功能分析的重点。关键感兴趣的是控制ATP水解速率，对肌动蛋白的亲和力和肌球蛋白移动肌动蛋白的速度的蛋白质部分。确定这些参数涉及的两个区域是蛋白质的25 kDa和50 kDa结构域以及50 kDa和20 kDa结构域交界处的“环”区域。然而，这些区域的序列在不同的肌球蛋白家族之间保守性很差，表明它们在进化上不受限制，因此对于肌球蛋白的功能而言相对不重要。为了解决这种明显的不一致，我们对观察到的进化变化的相对速率进行了分析。我们发现，当比较已知在动力学或发育上相似的肌球蛋白时，这些环区的序列似乎比其余的肌球蛋白分子的序列实际上更受约束。这表明这些环区可能在肌球蛋白功能中起重要作用，并支持它们参与调节功能上将一种肌球蛋白同工型与另一种肌球蛋白同工型区分开的特定动力学特征的想法。显然，“非保守”环通常可以在确定酶的动力学性质中起作用，并且类似的相对进化速率分析可能证明对研究其他蛋白质家族的结构-功能关系有用。版权所有1999，学术出版社。

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