Department of Bioscience and Biotechnology, Fukui Prefectural University, 4-1-1 Kenjojima, Matsuoka, Eiheiji-Town, Fukui 910-1195, Japan.
Int J Mol Sci. 2018 Nov 14;19(11):3596. doi: 10.3390/ijms19113596.
Heterotrimeric G proteins are the molecule switch that transmits information from external signals to intracellular target proteins in mammals and yeast cells. In higher plants, heterotrimeric G proteins regulate plant architecture. Rice harbors one canonical α subunit gene (), four extra-large GTP-binding protein genes (XLGs), one canonical β-subunit gene (), and five γ-subunit genes (tentatively designated , , ///, ////, and /) as components of the heterotrimeric G protein complex. Among the five γ-subunit genes, encodes the canonical γ-subunit, encodes a plant-specific type of γ-subunit with additional amino acid residues at the N-terminus, and the remaining three γ-subunit genes encode atypical γ-subunits with cysteine-rich C-termini. We characterized the //// gene product Gγ4 in the wild type (WT) and truncated protein Gγ4∆Cys in the //// mutant, , as littele information regarding the native Gγ4 and Gγ4∆Cys proteins is currently available. Based on liquid chromatography-tandem mass spectrometry analysis, immunoprecipitated Gγ4 candidates were confirmed as actual Gγ4. Similar to α-(Gα) and β-subunits (Gβ), Gγ4 was enriched in the plasma membrane fraction and accumulated in the developing leaf sheath. As //// mutants exhibited dwarfism, tissues that accumulated Gγ4 corresponded to the abnormal tissues observed in //// mutants.
三聚体 G 蛋白是一种分子开关，它将来自外部信号的信息传递到哺乳动物和酵母细胞中的细胞内靶蛋白。在高等植物中，三聚体 G 蛋白调节植物的结构。水稻含有一个典型的α亚基基因（）、四个特大 GTP 结合蛋白基因（XLGs）、一个典型的β亚基基因（）和五个γ亚基基因（暂定名为、、///、////和/），作为三聚体 G 蛋白复合物的组成部分。在五个γ亚基基因中，编码典型的γ亚基，编码一种具有 N 末端额外氨基酸残基的植物特异性γ亚基，其余三个γ亚基基因编码具有富含半胱氨酸的 C 末端的非典型γ亚基。我们对野生型（WT）中的 //// 基因产物 Gγ4 和 //// 突变体中的截短蛋白 Gγ4∆Cys 进行了表征，因为目前关于天然 Gγ4 和 Gγ4∆Cys 蛋白的信息很少。基于液相色谱-串联质谱分析，免疫沉淀的 Gγ4 候选物被确认为实际的 Gγ4。与 α-（Gα）和 β 亚基（Gβ）相似，Gγ4 富集在质膜部分，并在发育中的叶鞘中积累。由于 //// 突变体表现出矮化，积累 Gγ4 的组织与 //// 突变体中观察到的异常组织相对应。
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