Characterization of Heterotrimeric G Protein γ4 Subunit in Rice

Abstract

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 (RGA1), four extra-large GTP-binding protein genes (XLGs), one canonical β-subunit gene (RGB1), and five γ-subunit genes (tentatively designated RGG1, RGG2, RGG3/GS3/Mi/OsGGC1, RGG4/DEP1/DN1/qPE9-1/OsGGC3, and RGG5/OsGGC2) as components of the heterotrimeric G protein complex. Among the five γ-subunit genes, RGG1 encodes the canonical γ-subunit, RGG2 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 RGG4/DEP1/DN1/qPE9-1/OsGGC3 gene product Gγ4 in the wild type (WT) and truncated protein Gγ4∆Cys in the RGG4/DEP1/DN1/qPE9-1/OsGGC3 mutant, Dn1-1, 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 RGG4/DEP1/DN1/qPE9-1/OsGGC3 mutants exhibited dwarfism, tissues that accumulated Gγ4 corresponded to the abnormal tissues observed in RGG4/DEP1/DN1/qPE9-1/OsGGC3 mutants.

G-Protein β-Subunit Gene TaGB1-B Enhances Drought and Salt Resistance in Wheat

“…WD40 proteins are involved in various processes, such as growth and development, metabolite biosynthesis, and immune and stress responses [ 13 , 21 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 ]. Furthermore, it has been shown in Arabidopsis [ 15 , 46 , 47 ], rice [ 29 , 48 , 49 , 50 ], maize [ 51 , 52 , 53 ], and rapeseed [ 54 , 55 ] that G-proteins are involved in abiotic stresses. In this study, the qRT-PCR analysis showed that the expression of TaGB1-B changed under stress and hormone treatments ( Figure 2 a–i).…”

Proteomics Analysis of Plasma Membrane Fractions of the Root, Leaf, and Flower of Rice

“…Therefore, we immunologically concentrated the Gγ1 and Gγ2 subunits, and then detected them by LC-MS/MS. Gγ3 and Gγ4 in rice have been identified by IP [ 41 , 42 ]. Similar to Gγ1 and Gγ2, Gγ3, and Gγ4 are difficult to detect in trypsin-digested plasma membrane fractions by LC-MS/MS.…”

Plant Proteomic Research 2.0: Trends and Perspectives

“…Despite recent advancements, more emphasis needs to be given to the protein-extraction protocols, especially for proteins that are not abundant. Matsuta et al [30] and Nishiyama et al [31] used the mass spectrometry technique to identify heterotrimeric G γ4 and γ3 subunit proteins that are not abundant. As RGG4 / DEP1 / DN1 / qPE9-1 / OsGGC3 mutants exhibited dwarfism, the tissues that accumulated Gγ4 corresponded to the abnormal tissues observed in RGG4 / DEP1 / DN1 / qPE9-1 / OsGGC3 mutants [30].…”

“…Matsuta et al [30] and Nishiyama et al [31] used the mass spectrometry technique to identify heterotrimeric G γ4 and γ3 subunit proteins that are not abundant. As RGG4 / DEP1 / DN1 / qPE9-1 / OsGGC3 mutants exhibited dwarfism, the tissues that accumulated Gγ4 corresponded to the abnormal tissues observed in RGG4 / DEP1 / DN1 / qPE9-1 / OsGGC3 mutants [30]. On the other hand, as RGG3/GS3/Mi/OsGGC1 mutants show the characteristic phenotype in flowers and consequently in seeds, the tissues that accumulated Gγ3 corresponded to the abnormal tissues observed in RGG3/GS3/Mi/OsGGC1 mutants [31].…”

“…Subcellular proteomics has the potential to elucidate localized cellular responses and investigate communications among subcellular compartments during plant development and in response to biotic and abiotic stresses. This special issue includes the proteomic results in plasma membrane [4,30,31], chloroplast [11], and cell wall [17]. Additionally, the progress of proteomic research is understanding the post-translational modification such as phosphorylation [11,21,27].…”