Differential regulation of G protein signaling in <i>Arabidopsis</i> through two distinct pathways that internalize AtRGS1
Justin M. Watkins, Timothy J Ross-Elliott, Xiaoyi Shan, Fei Lou, Bernd H. Dreyer, Meral Tunc‐Ozdemir, Haiyan Jia, Jing Yang, Celio Cabral Oliveira, Luguang Wu, Yuri Trusov, Timothy D. Schwochert, Patrick J. Krysan, Alan M. Jones
Abstract
, GPCRs are not required for G protein-coupled signaling because the heterotrimeric G protein complex spontaneously exchanges nucleotide. Instead, the seven-transmembrane protein AtRGS1 modulates G protein signaling through ligand-dependent endocytosis, which initiates derepression of signaling without the involvement of canonical arrestins. Here, we found that endocytosis of AtRGS1 initiated from two separate pools of plasma membrane: sterol-dependent domains and a clathrin-accessible neighborhood, each with a select set of discriminators, activators, and candidate arrestin-like adaptors. Ligand identity (either the pathogen-associated molecular pattern flg22 or the sugar glucose) determined the origin of AtRGS1 endocytosis. Different trafficking origins and trajectories led to different cellular outcomes. Thus, in this system, compartmentation with its associated signalosome architecture drives biased signaling.