Dunn Alexander R, Spudich James A
Stanford University School of Medicine, Beckman Center, 279 Campus Drive, Stanford, California 94305-5307, USA.
Nat Struct Mol Biol. 2007 Mar;14(3):246-8. doi: 10.1038/nsmb1206. Epub 2007 Feb 11.
Myosin V moves cargoes along actin filaments by walking hand over hand. Although numerous studies support the basic hand-over-hand model, little is known about the fleeting intermediate that occurs when the rear head detaches from the filament. Here we use submillisecond dark-field imaging of gold nanoparticle-labeled myosin V to directly observe the free head as it releases from the actin filament, diffuses forward and rebinds. We find that the unbound head rotates freely about the lever-arm junction, a trait that likely facilitates travel through crowded actin meshworks.
肌球蛋白V通过交替移动的方式沿着肌动蛋白丝运输货物。尽管大量研究支持基本的交替移动模型，但对于后一个头部从肌动蛋白丝上脱离时出现的短暂中间体却知之甚少。在这里，我们使用金纳米颗粒标记的肌球蛋白V的亚毫秒暗场成像技术，直接观察游离头部从肌动蛋白丝上释放、向前扩散并重新结合的过程。我们发现，未结合的头部围绕杠杆臂连接处自由旋转，这一特性可能有助于其在拥挤的肌动蛋白网络中移动。
