DePina A S, Langford G M
Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire 03755-3576, USA.
Microsc Res Tech. 1999 Oct 15;47(2):93-106. doi: 10.1002/(SICI)1097-0029(19991015)47:2<93::AID-JEMT2>3.0.CO;2-P.
The transport of vesicles and the retention of organelles at specific locations are fundamental processes in cells. Actin filaments and myosin motors have been shown to be required for both of these tasks. Most of the organelles in cells associate with actin filaments and some of the myosin motors required for movement on actin filaments have been identified. Myosin V has been shown to transport endoplasmic reticulum (ER) vesicles in neurons, pigment granules in melanocytes, and the vacuole in yeast. Myosin I has been shown to be involved in the transport of Golgi-derived vesicles in epithelial cells. Myosin VI has been shown to be associated with Golgi-derived vesicles, and cytoplasmic vesicles in living Drosophila embryos. Myosin II may be a vesicle motor but its role in vesicle transport has not been resolved. Secretory vesicles, endosomes and mitochondria appear to be transported on actin filaments but the myosin motors on these organelles have not been identified. Mitochondria in yeast may be transported by the dynamic assembly of an actin "tail." The model that has unified all of these findings is the concept that long-range movement of vesicles occurs on microtubules and short-range movement on actin filaments. The details of how the microtubule-dependent and the actin-dependent motors are coordinated are important questions in the field. There is now strong evidence that two molecular motors, kinesin and myosin V, interact with each other and perhaps function as a complex on vesicles. An understanding of the interrelationship of microtubules and actin filaments and the motors that move cargo on them will ultimately establish how vesicles and organelles are transported to their specific locations in cells.
囊泡运输以及细胞器在特定位置的滞留是细胞中的基本过程。肌动蛋白丝和肌球蛋白马达已被证明是完成这两项任务所必需的。细胞中的大多数细胞器都与肌动蛋白丝相关联，并且已经鉴定出一些在肌动蛋白丝上运动所需的肌球蛋白马达。肌球蛋白V已被证明可在神经元中运输内质网（ER）囊泡、在黑素细胞中运输色素颗粒以及在酵母中运输液泡。肌球蛋白I已被证明参与上皮细胞中高尔基体衍生囊泡的运输。肌球蛋白VI已被证明与高尔基体衍生囊泡以及活果蝇胚胎中的细胞质囊泡相关联。肌球蛋白II可能是一种囊泡马达，但其在囊泡运输中的作用尚未明确。分泌囊泡、内体和线粒体似乎在肌动蛋白丝上运输，但这些细胞器上的肌球蛋白马达尚未被鉴定出来。酵母中的线粒体可能通过肌动蛋白“尾巴”的动态组装来运输。统一所有这些发现的模型是这样一个概念，即囊泡的长距离运动发生在微管上，而短距离运动发生在肌动蛋白丝上。微管依赖性和肌动蛋白依赖性马达如何协调的细节是该领域的重要问题。现在有强有力的证据表明，两种分子马达，驱动蛋白和肌球蛋白V，相互作用，并且可能在囊泡上作为一个复合体发挥作用。对微管和肌动蛋白丝以及在它们上面移动货物的马达之间相互关系的理解最终将确定囊泡和细胞器如何被运输到细胞中的特定位置。
