Retrieval of cargo proteins from the endosome towards the trans-Golgi network (TGN) is a crucial intracellular process for cellular homeostasis. Its dysfunction is associated with pathogenesis of Alzheimer and Parkinson's diseases. Myosin family proteins are cellular motors walking along actin filaments by utilizing the chemical energy from ATP hydrolysis, known to involve in pleiotropic cellular trafficking pathways. However, the question of whether myosins play a role in the trafficking of Snc1 and Vps10 has not been addressed yet. The present study assesses the potential roles of all five yeast myosins in the recycling of two membrane cargo, Snc1 and Vps10. It appears that all myosins except Myo2 are not required for the Snc1 traffic, while it was found that Myo1 and 2 play important roles for Vps10 retrieval from the endosome and the vacuole. Multiple myo2 mutants harboring a point mutation in the actin binding or the cargo binding tail domain were characterized to demonstrate abnormal Vps10-GFP and GFP-Snc1 distribution phenotypes, suggesting a severe defect in their sorting and trafficking at the endosome. Furthermore, Vps10-GFP patches in all tested myo2 mutants were found to be near stationary with quantitative live cell imaging. Finally, we found that actin cables in the myo2 mutant cells were considerably disrupted, which may aggravate the trafficking of Vps10 from the endosome. Together, our results provide novel insights into the function of Myo-family proteins in the recycling traffic of Vps10 and Snc1 destined for the TGN.

从内体向反式转运蛋白回收货物蛋白高尔基网络 (TGN) 是细胞内稳态的关键细胞内过程。其功能障碍与阿尔茨海默病和帕金森病的发病机制有关。肌球蛋白家族蛋白是通过利用来自 ATP 水解的化学能沿着肌动蛋白丝行走的细胞马达，已知参与多效性细胞运输途径。然而，肌球蛋白是否在 Snc1 和 Vps10 的贩运中发挥作用的问题尚未得到解决。本研究评估了所有五种酵母肌球蛋白在回收两种膜货物 Snc1 和 Vps10 中的潜在作用。似乎除了 Myo2 之外的所有肌球蛋白都不是 Snc1 流量所必需的，而发现 Myo1 和 2 在从内体和液泡中提取 Vps10 中起着重要作用。多个myo2在肌动蛋白结合或货物结合尾部结构域中含有点突变的突变体被表征为显示异常的 Vps10-GFP 和 GFP-Snc1 分布表型，表明它们在内体的分类和运输存在严重缺陷。此外，通过定量活细胞成像，发现所有测试的myo2突变体中的Vps10-GFP 补丁都接近静止。最后，我们发现myo2突变细胞中的肌动蛋白电缆被严重破坏，这可能会加剧 Vps10 从内体的运输。总之，我们的结果提供了对 Myo 家族蛋白在 Vps10 和 Snc1 运往 TGN 的回收流量中的功能的新见解。