Heterotrimeric G-Protein Signaling in Plants
Heterotrimeric GTP-binding proteins comprised of Gα, Gβ, and Gγ subunits are key regulators of a multitude of signaling pathways in all eukaryotes. In plants, these proteins are currently a focus of intense research due to their involvement in affecting many agronomically important traits such as seed yield, organ size, abscisic acid (ABA)-dependent signaling and stress responses, plant defense responses, symbiosis, and nitrogen use efficiency. The mechanistic details of G-protein signaling in modulating these processes remain largely unknown.
The core G-protein components and their activation/deactivation chemistries are broadly conserved all through the eukaryotic evolution; however, their regulatory mechanisms seem to have been rewired in plants to meet specific needs. A set of plant-specific G-protein components also exist that provide a new dimension to this well-characterized signaling pathway. The availability of extensive biochemical data, genetic resources, and sequence information from a variety of plant species has made it possible to compare the G-protein signaling pathways across phyla and between different plant species. Work done in the past two decades has established some of the norms of G-protein signaling in plants and sprung some surprises. This article provides a detailed account of G-protein signaling pathways in plants, their mechanistic details, how they might differ from the classical paradigm, and their importance in manipulating specific responses to generate plants for future needs.
KeywordsG-protein-coupled receptor (GPCR) GTPase activity-accelerating protein (GAP) GTPase Guanine nucleotide exchange factor (GEF) Heterotrimeric G-protein Phospholipase Receptor-like kinase (RLK) Regulator of G-protein signaling (RGS)
The author sincerely thanks several colleagues for multiple rounds of discussion during the writing of this book chapter. We also apologize to the colleagues whose work could not be cited due to space constraint. Research in the Pandey lab is supported by NIFA/AFRI (2015-67013-22964) and NSF (IOS-1557942 and MCB-1714693) grants to SP.
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