Organelle transport along microtubules in Xenopus melanophores:: Evidence for cooperation between multiple motors
Organelle transport along microtubules in Xenopus melanophores:: Evidence for cooperation between multiple motors
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DOI：
10.1529/biophysj.105.067843
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发表时间：
2006-01-01
影响因子：
3.4
通讯作者：
Gelfand, V
中科院分区：
文献类型：
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作者：
Levi, V;Serpinskaya, AS;Gelfand, V
非洲爪蟾的黑色素细胞器或黑素体，响应激素，分散在细胞质或聚集在核周区域。黑素体运输的微管马达，驱动蛋白-2和细胞质动力蛋白，和肌动蛋白马达，肌球蛋白-V。我们探讨了黑素体运输的调节沿着微管在体内使用一个新的快速跟踪程序，确定黑素体的位置，每10毫秒2纳米的精度。细胞质动力蛋白和驱动蛋白2在聚集和分散条件下的黑素体转运速度分布呈现多个峰值，不能用单一的高斯函数拟合。我们假设黑素小体的速度线性依赖于活跃马达的数量。根据这个模型，1到3个动力蛋白分子在负端方向上运输每个黑素小体。在正端方向上的运输主要由驱动蛋白-2的一到两个拷贝驱动。在聚集过程中，运输黑素体的动力蛋白的数量增加，而活性驱动蛋白-2的数量在聚集和分散过程中保持不变。因此，活性动力蛋白分子的数量调节黑素体运输的净方向。该模型还表明，相同极性的多个电机在黑素体运输过程中合作，而相反极性的电机不竞争。
Xenopus melanophores have pigment organelles or melanosomes which, in response to hormones, disperse in the cytoplasm or aggregate in the perinuclear region. Melanosomes are transported by microtubule motors, kinesin-2 and cytoplasmic dynein, and an actin motor, myosin-V. We explored the regulation of melanosome transport along microtubules in vivo by using a new fast-tracking routine, which determines the melanosome position every 10 ms with 2-nm precision. The velocity distribution of melanosomes transported by cytoplasmic dynein or kinesin-2 under conditions of aggregation and dispersion presented several peaks and could not befit with a single Gaussian function. We postulated that the melanosome velocity depends linearly on the number of active motors. According to this model, one to three dynein molecules transport each melanosome in the minus-end direction. The transport in the plus-end direction is mainly driven by one to two copies of kinesin-2. The number of dyneins transporting a melanosome increases during aggregation, whereas the number of active kinesin-2 stays the same during aggregation and dispersion. Thus, the number of active dynein molecules regulates the net direction of melanosome transport. The model also shows that multiple motors of the same polarity cooperate during the melanosome transport, whereas motors of opposite polarity do not compete.