Alvaro CG, O'Donnell AF, Prosser DC, Augustine AA, Goldman A, Brodsky JL, Cyert MS, Wendland B, Thorner J

G-protein-coupled receptors (GPCRs) are integral membrane proteins that initiate responses to extracellular stimuli by mediating ligand-dependent activation of cognate heterotrimeric G-proteins. In yeast, occupancy of GPCR Ste2 by peptide pheromone α-factor initiates signaling by releasing a stimulatory Gβγ complex (Ste4-Ste18) from its inhibitory Gα subunit (Gpa1). Prolonged pathway stimulation is ...

Read More

detrimental, and feedback mechanisms have evolved that act at the receptor level to limit the duration of signaling and stimulate recovery from pheromone-induced G1 arrest, including up-regulation of the expression of an α-factor-degrading protease (Bar1), a regulator of G-protein signaling protein (Sst2) that stimulates Gpa1-GTP hydrolysis, and Gpa1 itself. Ste2 is also down-regulated by endocytosis, both constitutive and ligand-induced. Ste2 internalization requires its phosphorylation and subsequent ubiquitinylation by membrane-localized protein kinases (Yck1 and Yck2) and a ubiquitin ligase (Rsp5). Here we demonstrate that three different members of the α-arrestin family (Ldb19/Art1, Rod1/Art4 and Rog3/Art7) contribute to Ste2 desensitization and internalization, and do so by discrete mechanisms. We provide genetic and biochemical evidence that Ldb19 and Rod1 recruit Rsp5 to Ste2 via PPxY motifs in their C-terminal regions; by contrast, the arrestin-fold domain at the N-terminus of Rog3 is sufficient to promote adaptation. Finally, we show that Rod1 function requires calcineurin-dependent dephosphorylation.

Date: May. 12, 2014

View in: Pubmed Google Scholar

164517