REGULATION OF DICTYOSTELIUM MYOSIN BY PHOSPHORYLATION

分子马达肌球蛋白与肌动蛋白的相互作用驱动肌肉 收缩和细胞形状和运动的各种变化， 非肌肉真核细胞生物学的基础。必不可少的 肌球蛋白在非肌细胞中的功能是调节其组装 变成细丝和更高级的结构，如收缩环， 其组装在空间和时间上受到控制。之甚少 已知这种空间和时间控制的分子基础， 肌球蛋白分子的磷酸化似乎起关键作用。 光 链磷酸化可以调节肌球蛋白丝组装在一些 系统，但可能主要控制肌球蛋白的运动功能。 重 链磷酸化可能主要参与肌球蛋白的调节 灯丝组件 本提案的具体目的是研究 网骨藻是一种允许肌球蛋白磷酸化的生物体， 生物化学、分子遗传学和生理学的融合 接近。 因此，它提供了一个独特的机会，调查 细胞如何移动，分裂和改变形状的分子基础 与细胞和发育信号有关。 下一步的实验计划 五年期间可分为三个部分： 1.激酶的生化、结构和分子遗传学研究 和负责控制网囊藻的磷酸酶 肌球蛋白磷酸化 2.生物化学和结构研究的影响，这些 磷酸化对纯化肌球蛋白功能的影响。 3.表征磷酸化对在体细胞内的细胞因子的影响。 肌球蛋白的行为和功能。 后者是最近应用先进的 分子遗传技术， 网骨藻

Interaction of the molecular motor myosin with actin drives muscle contraction and various changes in cell shape and movements that are fundamental to the biology of nonmuscle eukaryotic cells. Essential to the function of myosin in nonmuscle cells is the regulation of its assembly into filaments and higher order structures such as the contractile ring, the assembly of which is spatially and temporally controlled. Little is known about the molecular basis of such spatial and temporal control but phosphorylation of the myosin molecule appears to play a key role. Light chain phosphorylation may regulate myosin filament assembly in some systems, but may primarily control the motor function of myosin. Heavy chain phosphorylation may be primarily involved in regulation of myosin filament assembly. The specific aim of this proposal is to study the roles of myosin phosphorylation in Dictyostelium, an organism that allows the convergence of biochemical, molecular genetic, and physiological approaches. It therefore offers a unique opportunity to investigate the molecular basis of how a cell moves, divides, and changes shape in response to cellular and developmental signals. The experimental plan for the next five year period can be divided into three parts: 1. Biochemical, structural, and molecular genetic studies on the kinases and phosphatases that are responsible for the control of Dictyostelium myosin phosphorylations. 2. Biochemical and structural studies on the effects of these phosphorylations on the functions of purified myosin. 3. Characterization of the effects of phosphorylation on the in vivo behavior and function of the myosin. The latter is made possible by recent applications of sophisticated molecular genetic techniques to Dictyostelium.