Arai Seisuke, Noda Yoichi, Kainuma Satoko, Wada Ikuo, Yoda Koji
Department of Biotechnology, University of Tokyo, Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
Curr Biol. 2008 Jul 8;18(13):987-91. doi: 10.1016/j.cub.2008.06.028.
A yeast class V myosin Myo2 transports the Golgi into the bud during its inheritance. However, the mechanism that links the Golgi to Myo2 is unknown. Here, we report that Ypt11, a Rab GTPase that reportedly interacts with Myo2, binds to Ret2, a subunit of the coatomer complex. When Ypt11 is overproduced, Ret2 and the Golgi markers, Och1 and Sft2, are accumulated in the growing bud and are lost in the mother cell. In a ret2 mutant that produces the Ret2 protein with reduced affinity to Ypt11, no such accumulation is observed upon overproduction of Ypt11. At a certain stage of budding, it is known that the late Golgi cisternae labeled with Sec7-GFP show polarized distribution in the bud. We find that this polarization of late Golgi cisternae is not observed in the ypt11Delta mutant. Indeed, analyses of Sec7-GFP dynamics with spatio-temporal image correlation spectroscopy (STICS) and fluorescence loss in photobleaching (FLIP) reveals that Ypt11 is required for the vectorial actin-dependent movement of the late Golgi from the mother cell toward the emerging bud. These results indicate that the Ypt11 and Ret2 are components of a Myo2 receptor complex that functions during the Golgi inheritance into the growing bud.
酵母V类肌球蛋白Myo2在高尔基体遗传过程中将其转运至芽体中。然而，将高尔基体与Myo2连接起来的机制尚不清楚。在此，我们报道Ypt11，一种据报道与Myo2相互作用的Rab GTP酶，与外被体复合物的一个亚基Ret2结合。当Ypt11过量产生时，Ret2以及高尔基体标记物Och1和Sft2在生长中的芽体中积累，并在母细胞中消失。在一个产生与Ypt11亲和力降低的Ret2蛋白的ret2突变体中，过量产生Ypt11时未观察到这种积累。在出芽的某个阶段，已知用Sec7-GFP标记的晚期高尔基体潴泡在芽体中呈极化分布。我们发现，在ypt11Δ突变体中未观察到晚期高尔基体潴泡的这种极化现象。事实上，利用时空图像相关光谱法（STICS）和光漂白荧光损失法（FLIP）对Sec7-GFP动力学进行分析表明，Ypt11是晚期高尔基体从母细胞向新出现的芽体进行矢量肌动蛋白依赖性运动所必需的。这些结果表明，Ypt11和Ret2是在高尔基体遗传至生长中的芽体过程中发挥作用的Myo2受体复合物的组成部分。
