SINGLE MOLECULAR MECHANICS OF MYOSIN V

基于肌动蛋白和肌球蛋白的运动系统参与广泛的细胞运动功能，包括细胞器运输、变形运动和细胞分裂。已经发现了许多类型的肌球蛋白，它们都具有共同的酶促马达结构域，具有肌动蛋白结合和ATP水解活性。然而，颈部区域在长度和它们结合轻链的能力上不同。这一提议与最近发现的肌球蛋白，肌球蛋白V（M5）有关。M5具有伸长的颈部区域，具有结合六条轻链的潜力。有人提出，颈部充当刚性水平臂，其通过放大运动域中的小运动来产生运动和力。在本提案中，将通过测试具有不同颈长的突变M5分子来测试水平臂假设。在小鼠和人类中，已经确定了几种影响神经功能和色素沉积的突变。这些突变表明M5在细胞器运输中的作用。细胞器马达通常是进行性的。在这个建议中，它将确定如果一个单一的M5分子是进行性的，通过研究它的能力，采取多个步骤的肌动蛋白轨道每个扩散遇到。

Actin and myosin based motile systems are involved in a wide range of cellular motile functions including organelle transport, ameboid motion and cell division. Many types of myosin have been discovered all of which share a common enzymatic motor domain with actin binding and ATP hydrolytic activity. However, the neck regions differ in length and their ability to bind light chains. This proposal is concerned with a recently discovered myosin, Myosin V (M5). M5 has an elongated neck region with the potential to bind six light chains. It has been proposed that the neck acts as a rigid level arm that produces movement and force that produces movement and force by amplifying small movements in the motor domain. In this proposal the level arm hypothesis will be tested by testing mutant M5 molecules with varying neck lengths. In mice and humans, several mutations that affect neural function and pigment deposition have been identified. These mutations suggest a role for M5 in organelle transport. Organelle motors are typically processive. In this proposal it will be determined if a single M5 molecule is processive by studying its ability to take multiple steps on an actin track per diffusional encounter.