Nding signals from G protein-coupled receptors (GPCRs) to downstream pathways, and thus are involved in diverse cellular processes. In contrast to humans, which have 21 G genes, 5 G genes, and 12 G genes, Arabidopsis thaliana has only one particular G gene (GPA1), one particular G gene (AGB1), and 3 G genes (AGG1 GG3) (for a evaluation, see Jones and Assmann, 2004; Chakravorty et al., 2011). The physiological functions of plant G proteins is usually evaluated by using G protein-deficient mutants. Such studies have recommended that plant G proteins have roles in signal transduction of several stimuli like a stress-related phytohormone, abscisic acid (ABA) (for a assessment, see Perfus-Barbeoch et al., 2004). GPCRs around the plasma membrane inside a. thaliana have been shown to bind ABA (Liu et al., 2007; Pandey et al., 2009), supporting the importance of the G proteins in ABA signal transduction, though the validity of those studies is still in dispute (Gao et al.5371-70-0 Purity , 2007; Jaff?et al., 2012). G proteins are thought to mediate signal transduction via interacting with effector proteins and regulating their activities (to get a review, see Pierce et al., 2002). Numerous G protein effectors happen to be identified in animals, but only some of them exist in Arabidopsis or other plant species (for any assessment, see Jones and Assmann, 2004), suggesting that plants have plant-specific mechanisms for G protein signalling. In reality, some putative plant-specific G protein effectors happen to be?The Author [2013]. Published by Oxford University Press [on behalf in the Society for Experimental Biology]. This really is an Open Access short article distributed under the terms in the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/ by-nc/3.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, offered the original work is properly cited. For industrial re-use, please make contact with journals.permissions@oup3214 | Tsugama et al.identified. As an example, THYLAKOID FORMATION 1 (THF1) physically interacts with GPA1 and is involved in GPA1-mediated sugar signalling and chloroplast improvement (Huang et al., 2006; Zhang et al., 2009). A cupin domain-containing protein, AtPirin1, also physically interacts with GPA1 and mediates ABA signalling (Lapik and Kaufman, 2003). NDL1 (N-MYC DOWNREGULATEDLIKE1) physically interacts with AGB1 and regulates auxin distribution in plants (Mudgil et al., 2009). An acireductone dioxygenase-like protein, ARD1, also physically interacts with AGB1, and its enzyme activity is enhanced by G dimer (Friedman et al., 2011). Overexpression of a Golgi-localized hexose transporter, SGB1, partially suppresses the phenotype with the AGB1-null mutant, agb1-2 (H.196862-45-0 site X.PMID:24103058 Wang et al., 2006). A comprehensive evaluation on the G-protein interactome recommended that G proteins interact with cell wall-related proteins and thereby regulate the cell wall composition (Klopffleisch et al., 2011). On the other hand, the molecular mechanisms underlying G protein-mediated signalling stay to be elucidated. G proteins are suggested to play roles in signal transduction of a phytohormone, brassinosteroid (BR). By way of example, G deficiency causes BR hyposensitivities in each Arabidopsis (Ullah et al., 2001, 2002) and rice (L. Wang et al., 2006), and G deficiency in Arabidopsis enhances the dwarf phenotypes of bri1-5 and det2-1, which have defects in BR biosynthesis and BR perception, respectively (Gao et al., 2008). An AGB1null mutant, agb1-2, is hyposensitive to BR in seed germi.