[Objective]Regulation mechanism of GS3 protein in rice was investigated, in order to lay foundation for analyzing structure of plant G protein and perfecting regulation network of G protein. [Method]N-terminal domain of GS3 protein OSR and C-terminal domain of GS3 protein were expressed by inducing expression vectors pGEX-6p-1 and pET-28b-sumo, respectively. Then the gel filtration columns superdex 200/75 10/300 and ion exchange column Mono Q 5/50 were used to purify protein. The structures of GS3 and co-expression complex of GS3 and Gβ were studied by optimizing crystal and X-ray diffraction. [Result]The constructed recombinant proteins OSR-pGEX-6p-1 and GβN-pET-28b-sumo were co-expressed in Escherichia coli BL21(DE3). Then two bands were obtained by GST beads affinity chromatog-raphy, which were OSR-GST(31 kD) and GβN-sumo(26 kD), respectively. After Ni2+ beads affinity chromatography, two bands were still found. However, SDS-PAGE results showed that, four bands were found, including GST(26 kD), Sumo (17 kD), GβN(9 kD) and OSR(5 kD). The complex of GβN(9 kD) and OSR(5 kD) were obtained by separation and purification with ion exchange column Mono Q 5/50. The purified complex was concentrated to 12 mg/mL for crystal screening, but no crystal was obtained. [Conclusion]G protein in rice is consistent with the classical heterotrimeric G pro-tein model due to interaction of GS3 and Gβ that GS3 N-terminal domain OSR was integrated with Gβ N-terminal.%【目的】阐明GS3蛋白在水稻中的调控机制，为解析植物G蛋白的结构及完善G蛋白的调控网络打下基础。【方法】分别采用表达载体pGEX-6p-1和pET-28b-sumo诱导表达GS3蛋白N端结构域OSR和GS3蛋白C端结构域，再使用凝胶过滤柱Superdex 200/7510/300和阴例子交换层析柱Mono Q 5/50纯化表达蛋白，通过筛选优化晶体和X射线衍射的方法对GS3及GS3与Gβ共表达复合物的结构进行研究。【结果】将构建的重组蛋白OSR-pGEX-6p-1与GβN- pET-28b-sumo转入大肠杆菌BL21（DE3）中共表达，经GST beads亲和层析可获得2条条带，分别为OSR-GST（31 kD）和GβN-sumo（26 kD），再过Ni2+ beads亲和层析同样有2条条带，而SDS-PAGE凝胶电泳结果显示有4条条带，分别为GST（26 kD）、sumo（17 kD）、GβN（9 kD）和OSR（5 kD）。经阴例子交换层析柱Mono Q 5/50分离纯化可获得GβN（9 kD）和OSR（5 kD）二者的复合物。将纯化后的复合物浓缩至12 mg/mL进行晶体初筛，但未获得结晶。【结论】GS3和Gβ互作是通过GS3蛋白N端结构域OSR与Gβ N端结构域的结合而实现，其结果符合经典的G蛋白异源三聚体模型。
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