| Title: | Differential Phosphorylation Provides a Switch to Control How alpha-Arrestin Rod1 Down-regulates Mating Pheromone Response in Saccharomyces cerevisiae |
| Author(s): | Alvaro CG; Aindow A; Thorner J; |
| Address: | "Division of Biochemistry, Biophysics and Structural Biology, Department of Molecular and Cell Biology, University of California, Berkeley, California 94720-3202. Division of Biochemistry, Biophysics and Structural Biology, Department of Molecular and Cell Biology, University of California, Berkeley, California 94720-3202 jthorner@berkeley.edu" |
| DOI: | 10.1534/genetics.115.186122 |
| ISSN/ISBN: | 1943-2631 (Electronic) 0016-6731 (Print) 0016-6731 (Linking) |
| Abstract: | "G-protein-coupled receptors (GPCRs) are integral membrane proteins that initiate stimulus-dependent activation of cognate heterotrimeric G-proteins, triggering ensuing downstream cellular responses. Tight regulation of GPCR-evoked pathways is required because prolonged stimulation can be detrimental to an organism. Ste2, a GPCR in Saccharomyces cerevisiae that mediates response of MATa haploids to the peptide mating pheromone alpha-factor, is down-regulated by both constitutive and agonist-induced endocytosis. Efficient agonist-stimulated internalization of Ste2 requires its association with an adaptor protein, the alpha-arrestin Rod1/Art4, which recruits the HECT-domain ubiquitin ligase Rsp5, allowing for ubiquitinylation of the C-terminal tail of the receptor and its engagement by the clathrin-dependent endocytic machinery. We previously showed that dephosphorylation of Rod1 by calcineurin (phosphoprotein phosphatase 2B) is required for optimal Rod1 function in Ste2 down-regulation. We show here that negative regulation of Rod1 by phosphorylation is mediated by two distinct stress-activated protein kinases, Snf1/AMPK and Ypk1/SGK1, and demonstrate both in vitro and in vivo that this phospho-regulation impedes the ability of Rod1 to promote mating pathway desensitization. These studies also revealed that, in the absence of its phosphorylation, Rod1 can promote adaptation independently of Rsp5-mediated receptor ubiquitinylation, consistent with recent evidence that alpha-arrestins can contribute to cargo recognition by both clathrin-dependent and clathrin-independent mechanisms. However, in cells lacking a component (formin Bni1) required for clathrin-independent entry, Rod1 derivatives that are largely unphosphorylated and unable to associate with Rsp5 still promote efficient adaptation, indicating a third mechanism by which this alpha-arrestin promotes desensitization of the pheromone-response pathway" |
| Keywords: | "Adaptation, Biological Calcineurin/metabolism Down-Regulation Endosomal Sorting Complexes Required for Transport/metabolism Glycogen Synthase Kinase 3/metabolism Membrane Proteins/*metabolism Phosphorylation Protein Binding Protein Interaction Domains and;" |
| Notes: | "MedlineAlvaro, Christopher G Aindow, Ann Thorner, Jeremy eng R01 GM021841/GM/NIGMS NIH HHS/ T32 GM007232/GM/NIGMS NIH HHS/ Research Support, N.I.H., Extramural Research Support, Non-U.S. Gov't 2016/02/28 Genetics. 2016 May; 203(1):299-317. doi: 10.1534/genetics.115.186122. Epub 2016 Feb 26" |
