Receptor internalization in yeast requires the Tor2-Rho1 signaling pathway
Receptor internalization in yeast requires the Tor2-Rho1 signaling pathway
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DOI：
10.1091/mbc.e03-05-0323
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发表时间：
2003-11-01
影响因子：
3.3
通讯作者：
Hicke, L
中科院分区：
文献类型：
--
作者：
deHart, AKA;Schnell, JD;Hicke, L
来自细胞表面的蛋白质的有效内化对于调节细胞生长和分化是必不可少的。在筛选α因子受体的配体刺激内化缺陷的酵母突变体时，我们鉴定了TOR 2的突变等位基因tor 2（G2128 R）。已知Tor蛋白在翻译起始和营养感测中起作用，并且是细胞周期通过G1所需的。酵母Tor 2通过激活Rho 1鸟嘌呤核苷酸交换因子Rom 2在调节细胞壁完整性方面具有额外的作用。Tor 2（G2128 R）细胞中的内吞缺陷是由于这种Tor 2独特功能的破坏。对细胞完整性重要的其他蛋白质，Rom 2和细胞完整性传感器Wsc 1，也是有效内吞作用所必需的。在葡聚糖合酶Fks 1/2的激活中特异性缺陷的rho 1突变体不能有效地内化α-因子，并且fks 1Delta细胞表现出类似的表型。去除细胞壁不抑制内化，这表明Rho 1和Fks 1在胞吞作用中的功能不是通过细胞壁合成或结构完整性。这些发现揭示了一种新的功能Tor 2-Rho 1途径在控制酵母细胞内吞作用，这是一种功能，部分介导的质膜蛋白FKS 1。
Efficient internalization of proteins from the cell surface is essential for regulating cell growth and differentiation. In a screen for yeast mutants defective in ligand-stimulated internalization of the alpha-factor receptor, we identified a mutant allele of TOR2, tor2(G2128R). Tor proteins are known to function in translation initiation and nutrient sensing and are required for cell cycle progression through G1. Yeast Tor2 has an additional role in regulating the integrity of the cell wall by activating the Rho1 guanine nucleotide exchange factor Rom2. The endocytic defect in tor2(G2128R) cells is due to disruption of this Tor2 unique function. Other proteins important for cell integrity, Rom2 and the cell integrity sensor Wsc1, are also required for efficient endocytosis. A rho1 mutant specifically defective in activation of the glucan synthase Fks1/2 does not internalize alpha-factor efficiently, and fks1Delta cells exhibit a similar phenotype. Removal of the cell wall does not inhibit internalization, suggesting that the function of Rho1 and Fks1 in endocytosis is not through cell wall synthesis or structural integrity. These findings reveal a novel function for the Tor2-Rho1 pathway in controlling endocytosis in yeast, a function that is mediated in part through the plasma membrane protein Fks1.