Emerging themes in heterotrimeric G-protein signaling in plants

The Role of Gβ Protein in Controlling Cell Expansion via Potential Interaction with Lipid Metabolic Pathways

“…Studies performed for almost two decades show that G-proteins regulate processes fundamental to plant development and adaptation (Urano and Jones, 2014;Pandey and Vijayakumar, 2018); however, in most cases the underlying mechanisms remain unknown. As per the established paradigm, based mostly on the studies in metazoan systems, G-proteins cycle through the inactive and active forms for regulation of these responses, and in their active form, they must interact with different effectors.…”

“…The role of Gb proteins is central to plant G-protein signaling because in plants such as Arabidopsis or rice, where multiple Ga (canonical and extra-large) and Gg proteins exist, they all interact with the sole Gb protein (Chakravorty et al, 2015;Pandey and Vijayakumar, 2018). Consequently, knocking out of the Gb gene in these plants potentially eliminates the function of all Ga and all Gg genes as well, whereas knocking down of canonical Ga or extra-large Ga genes or one or more groups of Gg genes still allows for some signal to go through.…”

“…Inherent GTPase activity of Ga, aided by the regulatory GTPase activityaccelerating proteins, causes hydrolysis of bound GTP, returning Ga to its GDP-bound form, which reassociates with the Gbg dimer completing one signaling cycle. This synchronized activation and deactivation of the heterotrimeric G-protein complex (G-proteins, hereafter) allows for precise control of signal-response coupling (McCudden et al, 2005;Urano and Jones, 2014;Roy Choudhury and Pandey, 2016a;Pandey and Vijayakumar, 2018).…”

Control of grain size by G protein signaling in rice

“…Unlike animals, plant genomes encode few GPCRs, and plant Gα could be self‐activated (Johnston et al ; Urano et al ; Bradford et al ; Pandey and Vijayakumar ), suggesting that plant G proteins sense signals in different ways from those of animals. Several studies implied that receptor‐like kinases (RLKs) are potential factors that percept and transduce signals to G proteins (Lease et al ; Llorente et al ; Bommert et al ; Liu et al ; Ishida et al ; Aranda‐Sicilia et al ; Choudhury and Pandey ; Liang et al ; Yu et al ; Peng et al ).…”

“…However, knowledge about downstream effectors of plant G proteins is very limited. Plant genomes do not encode homologs of the well‐studied animal G protein effectors (Pandey and Vijayakumar ). Although a number of interacting factors of G proteins have been identified (Warpeha et al ; Mudgil et al ; Klopffleisch et al ; Hu et al ; Para et al ), none of them have been proven as effectors of G protein signaling.…”