Identification of Heterotrimeric G Protein α and β Subunits in Rice

Like those in mammals, heterotrimeric G protein complexes have been implicated in signal transduction pathways in plants; however, the subunits themselves have not been isolated. In this study, the rice heterotrimeric G protein subunits α (Gα) and β (Gβ) were purified by affinity chromatography using anti-Gα and -Gβ antibodies and SDS-PAGE. Six and seven peptides, respectively, were identified by mass spectrometry and identified as the translation products of the Gα gene RGA1 and Gβ gene RGB1. During purification, the subunits dissociated easily from the G protein complex.