Shiroguchi Katsuyuki, Kinosita Kazuhiko
Department of Physics, Faculty of Science and Engineering, Waseda University, Okubo 3-4-1, Shinjuku-ku, Tokyo 169-8555, Japan.
Science. 2007 May 25;316(5828):1208-12. doi: 10.1126/science.1140468.
Myosin V is a molecular motor that moves cargo along actin filaments. Its two heads, each attached to a long and relatively stiff neck, move alternately forward in a "hand-over-hand" fashion. To observe under a microscope how the necks move, we attached a micrometer-sized rod to one of the necks. The leading neck swings unidirectionally forward, whereas the trailing neck, once lifted, undergoes extensive Brownian rotation in all directions before landing on a site ahead of the leading head. The neck-neck joint is essentially free, and the neck motion supports a mechanism where the active swing of the leading neck biases the random motion of the lifted head to let it eventually land on a forward site.
肌球蛋白V是一种分子马达，可沿着肌动蛋白丝移动货物。它的两个头部，每个都连接到一个长且相对较硬的颈部，以“手拉手”的方式交替向前移动。为了在显微镜下观察颈部如何移动，我们将一根微米大小的杆连接到其中一个颈部。领先的颈部单向向前摆动，而落后的颈部一旦抬起，在落到领先头部前方的位置之前，会在各个方向上经历广泛的布朗旋转。颈部与颈部的关节基本上是自由的，颈部的运动支持一种机制，即领先颈部的主动摆动使抬起的头部的随机运动产生偏差，使其最终落在前方的位置。
