Sheetz M P, Steuer E R, Schroer T A
Trends Neurosci. 1989 Nov;12(11):474-8. doi: 10.1016/0166-2236(89)90099-4.
Recent in vitro studies of microtubule-dependent organelle movement have provided a great deal of information on the molecular mechanism of fast axonal transport. Microtubule-dependent organelle movement occurs in most cells, but in neurons active transport is absolutely necessary for materials to travel from the cell body to the synapse. Since fast transport is crucial for neuronal survival, it is likely that specialized regulatory mechanisms have been developed. It is clear that the microtubule-based motors, kinesin and cytoplasmic dynein are the enzymes that power organelle motility; however, additional cytoplasmic components are required to create an 'organelle translocation complex' that is competent for transport. Organelle transport might be regulated at the level of any of these components, i.e. the motors, their accessory factors, or the organelle binding sites. The direction of organelle movement is probably governed by the membrane binding site. In this review we discuss these topics and consider the mechanism of transport of the retrograde motor, cytoplasmic dynein, to the nerve terminal, and possible ways that unidirectional transport could occur on the non-polarized array of microtubules found in some dendrites.
最近关于微管依赖性细胞器运动的体外研究为快速轴突运输的分子机制提供了大量信息。微管依赖性细胞器运动发生在大多数细胞中，但在神经元中，主动运输对于物质从细胞体运输到突触是绝对必要的。由于快速运输对神经元的存活至关重要，很可能已经形成了专门的调节机制。很明显，基于微管的马达蛋白、驱动蛋白和细胞质动力蛋白是驱动细胞器运动的酶；然而，还需要额外的细胞质成分来形成一个能够进行运输的“细胞器转运复合体”。细胞器运输可能在这些成分中的任何一个水平上受到调节，即马达蛋白、它们的辅助因子或细胞器结合位点。细胞器运动的方向可能由膜结合位点控制。在这篇综述中，我们讨论这些话题，并考虑逆行马达蛋白——细胞质动力蛋白向神经末梢运输的机制，以及在某些树突中发现的非极化微管阵列上可能发生单向运输的方式。
