异源三聚体G蛋白由Gα、Gβ和Gγ 3个亚基组成,是普遍存在于真核细胞中的跨膜信号转导因子。植物细胞通过定位于细胞质膜的G蛋白信号调节子RGS蛋白(regulator of G protein signaling),调控异源三聚体G蛋白的活性,进而参与生长发育、激...异源三聚体G蛋白由Gα、Gβ和Gγ 3个亚基组成,是普遍存在于真核细胞中的跨膜信号转导因子。植物细胞通过定位于细胞质膜的G蛋白信号调节子RGS蛋白(regulator of G protein signaling),调控异源三聚体G蛋白的活性,进而参与生长发育、激素和糖信号转导以及抗病反应等多个重要生物学过程。膜蛋白可通过胞吞循环调控其在细胞质膜上的数量,以响应外界环境因子和自身发育信号。近年来,研究表明多种外界信号诱导拟南芥AtRGS1蛋白的胞吞,进而促进其与Gα亚基的解离,游离的Gα-GTP、Gβγ亚基和定位于内含体的AtRGS1蛋白均可能调控下游信号转导,进而影响相应生物学过程。本文综述了AtRGS1通过胞吞作用调控G蛋白参与的生长发育和抗性反应的分子细胞学机制研究进展,以期为深入理解G蛋白信号调节子影响植物发育进程和抗性反应的作用机制提供理论参考,为植物膜蛋白胞吞调控信号转导提供新的视角。展开更多
The secretory pathway is responsible for the transport of newly synthesized transmembrane proteins from the endoplasmic reticulum to their destinations via the Golgi/trans-Golgi network （TGN）, Cargo proteins at each...The secretory pathway is responsible for the transport of newly synthesized transmembrane proteins from the endoplasmic reticulum to their destinations via the Golgi/trans-Golgi network （TGN）, Cargo proteins at each sta- tion are actively sorted by specific sorting signals on the cargo and the corresponding coat complexes. Here, we used the Arabidopsis regulator of G-protein signaling （AtRGS1）, which contains an N-terminal potentially sensing glucose seven-transmembrane domain and a C-terminal RGS domain, as a model to uncover sorting motifs required for its cell surface expression. Expression of wild-type and truncated or mutated AtRGS1 fluorescent fusion proteins identified two cysteine residues in the extracellular N-terminus that are essential for endoplasmic reticulum exit and/or correct folding of AtRGS1. The linker between the seven-transmembrane and RGS domains contains an endoplasmic reticulum export signal, whereas the C-terminus is dispensable for the plasma membrane expression of AtRGS1. Interestingly, deletion of the RGS domain results in Golgi/TGN localization of the truncated AtRGS1. Further analysis using site-directed mutagen- esis showed that a tyrosine-based motif embedded in the RGS domain is essential for Golgi/TGN export of AtRGS1. These results reveal a new role for the RGS domain in regulating AtRGS1 trafficking from the Golgi/TGN to the plasma membrane and explain the interaction between the seven-transmembrane and RGS domains.展开更多
文摘异源三聚体G蛋白由Gα、Gβ和Gγ 3个亚基组成,是普遍存在于真核细胞中的跨膜信号转导因子。植物细胞通过定位于细胞质膜的G蛋白信号调节子RGS蛋白(regulator of G protein signaling),调控异源三聚体G蛋白的活性,进而参与生长发育、激素和糖信号转导以及抗病反应等多个重要生物学过程。膜蛋白可通过胞吞循环调控其在细胞质膜上的数量,以响应外界环境因子和自身发育信号。近年来,研究表明多种外界信号诱导拟南芥AtRGS1蛋白的胞吞,进而促进其与Gα亚基的解离,游离的Gα-GTP、Gβγ亚基和定位于内含体的AtRGS1蛋白均可能调控下游信号转导,进而影响相应生物学过程。本文综述了AtRGS1通过胞吞作用调控G蛋白参与的生长发育和抗性反应的分子细胞学机制研究进展,以期为深入理解G蛋白信号调节子影响植物发育进程和抗性反应的作用机制提供理论参考,为植物膜蛋白胞吞调控信号转导提供新的视角。
文摘The secretory pathway is responsible for the transport of newly synthesized transmembrane proteins from the endoplasmic reticulum to their destinations via the Golgi/trans-Golgi network （TGN）, Cargo proteins at each sta- tion are actively sorted by specific sorting signals on the cargo and the corresponding coat complexes. Here, we used the Arabidopsis regulator of G-protein signaling （AtRGS1）, which contains an N-terminal potentially sensing glucose seven-transmembrane domain and a C-terminal RGS domain, as a model to uncover sorting motifs required for its cell surface expression. Expression of wild-type and truncated or mutated AtRGS1 fluorescent fusion proteins identified two cysteine residues in the extracellular N-terminus that are essential for endoplasmic reticulum exit and/or correct folding of AtRGS1. The linker between the seven-transmembrane and RGS domains contains an endoplasmic reticulum export signal, whereas the C-terminus is dispensable for the plasma membrane expression of AtRGS1. Interestingly, deletion of the RGS domain results in Golgi/TGN localization of the truncated AtRGS1. Further analysis using site-directed mutagen- esis showed that a tyrosine-based motif embedded in the RGS domain is essential for Golgi/TGN export of AtRGS1. These results reveal a new role for the RGS domain in regulating AtRGS1 trafficking from the Golgi/TGN to the plasma membrane and explain the interaction between the seven-transmembrane and RGS domains.
