Regulation Of Smooth and Nonmuscle Myosin

非肌肉肌球蛋白II分子在细胞内具有广泛的功能。有三个非肌肉肌球蛋白II基因。我们用溶液动力学方法研究了非肌肉肌球蛋白IIA和IIB中ADP释放机制的应变依赖性。结果表明，阳性菌株促进ADP的释放，而阴性菌株则显著降低ADP的释放速率。这些结果表明，这些肌球蛋白，特别是非肌肉肌球蛋白IIB，非常适合作为细胞中的张力承担者。我们现在正在使用光学捕获纳米计量学来扩展对非肌肉肌球蛋白IIA和IIB的研究。此外，我们还与另一个研究小组合作，研究了非肌肉肌球蛋白IIA和IIB的杠杆臂位置依赖于ADP的变化。 我们已经表达了带有GFP标记的调节轻链(RLC)的非肌肉肌球蛋白IIA，特别感兴趣的是当这个轻链没有被磷酸化时，肌球蛋白是否仍然处于关闭状态。数据显示，GFP标签不干扰肌球蛋白的调节。

Nonmuscle myosin II molecules carry out a wide variety of functions within cells. There are three nonmuscle myosin II genes. We have studied the strain dependence of the ADP release mechanism in nonmuscle myosin IIA and IIB using a solution kinetic approach. The results show that positive strains accelerate the rate of ADP release whereas negative strain markedly lowers the rate. These results suggest that these myosins, and particularly nonmuscle myosin IIB, are ideally suited to act as tension bearers in cells. We are now using optical trapping nanometry to extend these studies on both nonmuscle myosin IIA and IIB. In addition we have collaborated with another group to examine the ADP-dependent change in lever arm position of nonmuscle myosins IIA and IIB. We have expressed nonmuscle myosin IIA with a GFP-tagged regulatory light chain (RLC) with particular interest in whether the myosin would still adopt the off state when this light chain is not phosphorylated. The data show that the GFP tag does not interfere with regulation of the myosin.