Abe Mitsuhiro, Qadota Hiroshi, Hirata Aiko, Ohya Yoshikazu
Dept. of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, FSB-101, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan.
J Cell Biol. 2003 Jul 7;162(1):85-97. doi: 10.1083/jcb.200301022.
Rho1p, an essential Rho-type GTPase in Saccharomyces cerevisiae, activates its effectors in the GTP-bound form. Here, we show that Rho1p in secretory vesicles cannot activate 1,3-beta-glucan synthase, a cell wall synthesizing enzyme, during vesicular transport to the plasma membrane. Analyses with an antibody preferentially reacting with the GTP-bound form of Rho1p revealed that Rho1p remains in the inactive form in secretory vesicles. Rom2p, the GDP/GTP exchange factor of Rho1p, is preferentially localized on the plasma membrane even when vesicular transport is blocked. Overexpression of Rom2p results in delocalization of Rom2p and accumulation of 1,3-beta-glucan in secretory vesicles. Based on these results, we propose that Rho1p is kept inactive in intracellular secretory organelles, resulting in repression of the activity of the cell wall-synthesizing enzyme within cells.
Rho1p是酿酒酵母中一种必需的Rho型GTP酶，它以GTP结合形式激活其效应器。在此，我们表明，分泌囊泡中的Rho1p在向质膜的囊泡运输过程中无法激活细胞壁合成酶1,3-β-葡聚糖合酶。用优先与Rho1p的GTP结合形式反应的抗体进行分析表明，Rho1p在分泌囊泡中保持无活性形式。Rho1p的GDP / GTP交换因子Rom2p即使在囊泡运输受阻时也优先定位于质膜上。Rom2p的过表达导致Rom2p的定位异常以及分泌囊泡中1,3-β-葡聚糖的积累。基于这些结果，我们提出Rho1p在细胞内分泌细胞器中保持无活性，从而导致细胞内细胞壁合成酶的活性受到抑制。
Zotero 插件
