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首页> 美国卫生研究院文献>Biophysical Journal >Structural-Functional Relationships of the Dynein Spokes and Central-Pair Projections Predicted from an Analysis of the Forces Acting within a Flagellum
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Structural-Functional Relationships of the Dynein Spokes and Central-Pair Projections Predicted from an Analysis of the Forces Acting within a Flagellum

机译：Dynein辐条和中央对投影的结构-功能关系从鞭毛内作用力的分析预测。

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In the axoneme of eukaryotic flagella the dynein motor proteins form crossbridges between the outer doublet microtubules. These motor proteins generate force that accumulates as linear tension, or compression, on the doublets. When tension or compression is present on a curved microtubule, a force per unit length develops in the plane of bending and is transverse to the long axis of the microtubule. This transverse force (t-force) is evaluated here using available experimental evidence from sea urchin sperm and bull sperm. At or near the switch point for beat reversal, the t-force is in the range of 0.25–1.0 nN/μm, with 0.5 nN/μm the most likely value. This is the case in both beating and arrested bull sperm and in beating sea urchin sperm. The total force that can be generated (or resisted) by all the dyneins on one micron of outer doublet is also ∼0.5 nN. The equivalence of the maximum dynein force/μm and t-force/μm at the switch point may have important consequences. Firstly, the t-force acting on the doublets near the switch point of the flagellar beat is sufficiently strong that it could terminate the action of the dyneins directly by strongly favoring the detached state and precipitating a cascade of detachment from the adjacent doublet. Secondly, after dynein release occurs, the radial spokes and central-pair apparatus are the structures that must carry the t-force. The spokes attached to the central-pair projections will bear most of the load. The central-pair projections are well-positioned for this role, and they are suitably configured to regulate the amount of axoneme distortion that occurs during switching. However, to fulfill this role without preventing flagellar bend formation, moveable attachments that behave like processive motor proteins must mediate the attachment between the spoke heads and the central-pair structure.
机译：在真核鞭毛的轴突中，动力蛋白运动蛋白在外部双峰微管之间形成交叉桥。这些运动蛋白产生的力以线性张力或压缩形式累积在双峰上。当弯曲的微管上存在张力或压缩时，在弯曲的平面中会产生每单位长度的力，该力垂直于微管的长轴。此处使用来自海胆精子和公牛精子的可用实验证据评估该横向力（t力）。在节拍反转的切换点处或附近，t力在0.25–1.0 nN /μm的范围内，最可能的值为0.5 nN /μm。殴打和逮捕公牛精子以及殴打海胆精子都是这种情况。一英寸外双峰上的所有达因可以产生（或抵抗）的总力也约为0.5 nN。转换点处的最大达因力/μm和t-力/μm的等效值可能会产生重要影响。首先，作用在鞭毛节拍转换点附近的双联体上的t力足够强，以至于它可以通过强烈地促进脱离状态并促使相邻双联体脱离而直接终止达因的作用。其次，在释放达因后，辐条和中心对装置是必须承受t力的结构。连接到中央对凸出部分的辐条将承担大部分负载。中心对突出部在该角色上位置适当，并且已适当配置以调节在切换过程中发生的轴突失真量。但是，要在不防止鞭毛弯曲形成的情况下发挥这一作用，必须像辐照性运动蛋白一样移动可移动的附件，以介导辐条头和中央对结构之间的附件。

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