Observing cycling of a few cross-bridges during isometric contraction of skeletal muscle.
Observing cycling of a few cross-bridges during isometric contraction of skeletal muscle.
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DOI：
10.1002/cm.20453
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发表时间：
2010-06
期刊：
影响因子：
2.9
通讯作者：
Borejdo, J.
中科院分区：
文献类型：
--
作者：
Mettikolla, P.;Calander, N.;Luchowski, P.;Gryczynski, I.;Gryczynski, Z.;Borejdo, J.
在肌肉收缩过程中，肌球蛋白跨桥将周期性的力脉冲传递给肌动蛋白。我们可以通过观察几个肌动蛋白或肌球蛋白分子来观察这些冲动。我们通过测量肌动蛋白荧光的平行偏振强度，跟踪了几种肌动蛋白分子在等长收缩过程中取向变化的时间过程。肌动蛋白的取向反映了细丝的局部弯曲，当横桥与F-肌动蛋白结合或分离时，肌动蛋白的取向不同。取向的变化的特点是活动期间，肌球蛋白跨桥相互作用正常与肌动蛋白，穿插与期间的不活动，肌动蛋白和肌球蛋白不能相互作用。活动周期平均持续1.2 ± 0.4 s，平均间隔2.3 ± 1.0 s。在激活期，肌动蛋白取向在两个极值之间振荡，其ON和OFF时间分别为0.4±0.2和0.7± 0.4s。当低浓度ATP引起收缩时，活动时间和非活动时间均较长且近似相等。这些结果表明，交叉桥与肌动蛋白的相互作用是爆发式的，并表明在活跃期，平均36%的交叉桥参与了力的产生。
During muscle contraction a myosin cross-bridge imparts periodic force impulses to actin. It is possible to visualize those impulses by observing a few molecules of actin or myosin. We have followed the time course of orientation change of a few actin molecules during isometric contraction by measuring parallel polarized intensity of its fluorescence. The orientation of actin reflects local bending of a thin filament and is different when a cross-bridge binds to, or is detached from, F-actin. The changes in orientation were characterized by periods of activity during which myosin cross-bridges interacted normally with actin, interspersed with periods of inactivity during which actin and myosin were unable to interact. The periods of activity lasted on average 1.2 ± 0.4 s and were separated on average by 2.3 ± 1.0 s. During active period, actin orientation oscillated between the two extreme values with the ON and OFF times of 0.4±0.2 and 0.7±0.4 s, respectively. When the contraction was induced by a low concentration of ATP both active and inactive times were longer and approximately equal. These results imply that cross-bridges interact with actin in bursts and suggest that during active period, on average 36% of cross-bridges are involved in force generation.
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影响因子：
3.4
作者：
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通讯作者：
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影响因子：
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