title: Specific α-arrestins negatively regulate Saccharomyces cerevisiae pheromone response by down-modulating the G-protein-coupled receptor Ste2.
abstract: 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 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 upregulation 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 downregulated 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 they 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; in 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.
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Alvaro
authors.forename: Allyson F
authors.initials: AF
authors.lastname: O'Donnell
authors.forename: Derek C
authors.initials: DC
authors.lastname: Prosser
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Augustine
authors.forename: Aaron
authors.initials: A
authors.lastname: Goldman
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Brodsky
authors.forename: Martha S
authors.initials: MS
authors.lastname: Cyert
authors.forename: Beverly
authors.initials: B
authors.lastname: Wendland
authors.forename: Jeremy
authors.initials: J
authors.lastname: Thorner
mesh_terms: D019390:Arrestins / Q000378:metabolism*; D019703:Calcineurin / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002453:Cell Cycle; D056827:Endosomal Sorting Complexes Required for Transport / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D000072235:Mating Factor; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism; D010675:Pheromones / Q000378:metabolism; D010766:Phosphorylation; D051964:Receptors, Mating Factor / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D043743:Ubiquitin-Protein Ligase Complexes / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination
chemical_list: D019390:Arrestins; D002352:Carrier Proteins; D056827:Endosomal Sorting Complexes Required for Transport; C533888:LDB19 protein, S cerevisiae; D008565:Membrane Proteins; D010455:Peptides; D010675:Pheromones; C099318:ROD1 protein, S cerevisiae; D051964:Receptors, Mating Factor; C498031:STE2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D000072235:Mating Factor; D043743:Ubiquitin-Protein Ligase Complexes; D019703:Calcineurin; C469287:RSP5 protein, S cerevisiae