Actin Sliding Velocities are Influenced by the Driving Forces of Actin-Myosin Binding.
Actin Sliding Velocities are Influenced by the Driving Forces of Actin-Myosin Binding.
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肌动蛋白滑动速度受肌动蛋白-肌球蛋白结合驱动力的影响。
DOI：
10.1007/s12195-013-0274-y
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发表时间：
2013
影响因子：
2.8
通讯作者：
Baker,JoshE
中科院分区：
文献类型：
--
作者：
Stewart,TravisJ;JacksonJr,DelRay;Smith,RyanD;Shannon,StevenF;Cremo,ChristineR;Baker,JoshE
肌肉的无负荷缩短速度V被认为受肌动蛋白结合的肌凝蛋白头的限制，orV=a·d·τon - 1，其中τon - 1是肌凝蛋白与肌动蛋白分离的速率，并决定肌凝蛋白的步长。该术语描述了肌凝蛋白头部之间的力传递效率，并且在运动试验中已显示在低肌凝蛋白密度下变为小于1。无机磷酸盐（Pi）和blebbistatin等分子抑制vv和肌动蛋白-肌球蛋白的强结合动力学，表明vv和附着动力学之间存在联系。为了确定这些小分子是通过增加对肌动蛋白滑动的阻力还是通过降低力传递的效率来减缓，我们确定了在体外滑动试验中，vby和blebbistatin的抑制作用如何改变施加在肌动蛋白丝上的力，通过测量肌动蛋白丝断裂的速率τbreak - 1来测量。在低（30μ m） [ATP]中加入30 mMPito后，τbreak - 1从1.8 μm s−1下降到1.3μm s−1，τbreak - 1从0.029 s−1下降到0.018 s−1。在低[ATP]运动缓冲液中加入50μM blebbistatin后，τbreak - 1从1.0 μm s−1下降到0.7μm s−1，τbreak - 1从0.059下降到0.022 s−1。这些结果表明，blebbistatin和pislowv通过减少力传递，而不是通过增加阻力，这意味着肌动蛋白-肌球蛋白附着动力学影响v。
Unloaded shortening speeds,V, of muscle are thought to be limited by actin-bound myosin heads that resist shortening, orV=a·d·τon−1whereτon−1is the rate at which myosin detaches from actin anddis myosin’s step size. Thea-term describes the efficiency of force transmission between myosin heads, and has been shown to become less than one at low myosin densities in a motility assay. Molecules such as inorganic phosphate (Pi), and blebbistatin inhibit bothVand actin-myosin strong binding kinetics suggesting a link betweenVand attachment kinetics. To determine whether these small molecules slowVby increasing resistance to actin sliding or by decreasing the efficiency of force transmission,a, we determine how inhibition ofVbyPiand blebbistatin changes the force exerted on actin filaments during anin vitrosliding assay, measured from changes in the rate,τbreak−1, at which actin filaments break. Upon addition of 30 mMPito a low (30μM) [ATP] motility bufferVdecreased from 1.8 to 1.3μm s−1andτbreak−1from 0.029 to 0.018 s−1. Upon addition of 50μM blebbistatin to a low [ATP] motility buffer,Vdecreased from 1.0 to 0.7μm s−1andτbreak−1from 0.059 to 0.022 s−1. These results imply that blebbistatin andPislowVby decreasing force transmission,a, not by increasing resistive forces, implying that actin-myosin attachment kinetics influenceV.