Regulation Of Smooth and Nonmuscle Myosin

非肌肉肌球蛋白II分子在细胞内执行各种各样的功能。有三个非肌肉肌球蛋白II基因。我们采用溶液动力学方法研究了非肌球蛋白IIA和IIB中ADP释放机制的应变依赖性。结果表明，阳性菌株能加快ADP的释放速度，而阴性菌株能显著降低ADP的释放速度。这些结果表明，这些肌球蛋白，特别是非肌球蛋白IIB，非常适合在细胞中充当张力承载体。我们现在使用光学捕获纳米测量法将这些研究扩展到非肌肉肌球蛋白IIA和IIB。此外，我们还与另一组合作研究了非肌肉肌球蛋白IIA和IIB杠杆臂位置的adp依赖性变化。

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.