Tropomyosin-containing actin cables direct the Myo2p-dependent polarized delivery of secretory vesicles in budding yeast
Tropomyosin-containing actin cables direct the Myo2p-dependent polarized delivery of secretory vesicles in budding yeast
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DOI：
10.1083/jcb.143.7.1931
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发表时间：
1998-12-28
影响因子：
7.8
通讯作者：
Bretscher, A
中科院分区：
文献类型：
--
作者：
Pruyne, DW;Schott, DH;Bretscher, A
出芽酵母的肌动蛋白细胞骨架由皮质斑块和索组成，两者都向细胞生长区域极化。原肌球蛋白特异定位于肌动蛋白索而非皮质斑块。当将原肌凝蛋白条件缺陷的细胞转移到限制温度时，肌动蛋白电缆在1分钟内消失，非常规的V类肌凝蛋白Myo2p和分泌囊泡相关的Rab GTPase Sec4p都迅速去极化。芽停止生长，母细胞向各向同性生长。当返回到允许温度时，含有原肌球蛋白的电缆在极化阵列中在1分钟内重新形成。电缆重组允许新生电缆焦点处Myo2p的快速富集，以及Myo2p依赖的Sec4p和囊外蛋白Sec8p的募集，以及芽萌发的开始。随着肌动蛋白电缆的丢失，皮质斑块在细胞内缓慢呈现各向同性分布，只有在电缆恢复后才会重极化。因此，肌动蛋白电缆对极性信号的响应独立于皮质斑块的总体分布，并且能够直接靶向myo2p依赖性分泌囊泡的递送和生长的极化。
The actin cytoskeleton in budding yeast consists of cortical patches and cables, both of which polarize toward regions of cell growth. Tropomyosin localizes specifically to actin cables and not cortical patches. Upon shifting cells with conditionally defective tropomyosin to restrictive temperatures, actin cables disappear within 1 min and both the unconventional class V myosin Myo2p and the secretory vesicle-associated Rab GTPase Sec4p depolarize rapidly. Bud growth ceases and the mother cell grows isotropically. When returned to permissive temperatures, tropomyosin-containing cables reform within 1 min in polarized arrays. Cable reassembly permits rapid enrichment of Myo2p at the focus of nascent cables as well as the Myo2p-dependent recruitment of Sec4p and the exocyst protein Sec8p, and the initiation of bud emergence. With the loss of actin cables, cortical patches slowly assume an isotropic distribution within the cell and will repolarize only after restoration of cables. Therefore, actin cables respond to polarity cues independently of the overall distribution of cortical patches and are able to directly target the Myo2p-dependent delivery of secretory vesicles and polarization of growth.