| Title: | Guanine nucleotide-binding protein (Galpha) endocytosis by a cascade of ubiquitin binding domain proteins is required for sustained morphogenesis and proper mating in yeast |
| Author(s): | Dixit G; Baker R; Sacks CM; Torres MP; Dohlman HG; |
| Address: | "From the Department of Biochemistry and Biophysics. Department of Biology, and. School of Biology, Georgia Institute of Technology, Atlanta, Georgia 30332. From the Department of Biochemistry and Biophysics, Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599 and hdohlman@med.unc.edu" |
| ISSN/ISBN: | 1083-351X (Electronic) 0021-9258 (Print) 0021-9258 (Linking) |
| Abstract: | "Heterotrimeric G proteins are well known to transmit signals from cell surface receptors to intracellular effector proteins. There is growing appreciation that G proteins are also present at endomembrane compartments, where they can potentially interact with a distinct set of signaling proteins. Here, we examine the cellular trafficking function of the G protein alpha subunit in yeast, Gpa1. Gpa1 contains a unique 109-amino acid insert within the alpha-helical domain that undergoes a variety of posttranslational modifications. Among these is monoubiquitination, catalyzed by the NEDD4 family ubiquitin ligase Rsp5. Using a newly optimized method for G protein purification together with biophysical measures of structure and function, we show that the ubiquitination domain does not influence enzyme activity. By screening a panel of 39 gene deletion mutants, each lacking a different ubiquitin binding domain protein, we identify seven that are necessary to deliver Gpa1 to the vacuole compartment including four proteins (Ede1, Bul1, Ddi1, and Rup1) previously not known to be involved in this process. Finally, we show that proper endocytosis of the G protein is needed for sustained cellular morphogenesis and mating in response to pheromone stimulation. We conclude that a cascade of ubiquitin-binding proteins serves to deliver the G protein to its final destination within the cell. In this instance and in contrast to the previously characterized visual system, endocytosis from the plasma membrane is needed for proper signal transduction rather than for signal desensitization" |
| Keywords: | "Adenosine Triphosphate/metabolism Amino Acid Sequence Carrier Proteins/genetics/*metabolism Crosses, Genetic *Endocytosis GTP-Binding Protein alpha Subunits, Gq-G11/chemistry/genetics/*metabolism Green Fluorescent Proteins/genetics/metabolism Immunoblotti;" |
| Notes: | "MedlineDixit, Gauri Baker, Rachael Sacks, Carly M Torres, Matthew P Dohlman, Henrik G eng P30 CA016086/CA/NCI NIH HHS/ R01 GM101560/GM/NIGMS NIH HHS/ GM101560/GM/NIGMS NIH HHS/ Research Support, N.I.H., Extramural 2014/04/12 J Biol Chem. 2014 May 23; 289(21):15052-63. doi: 10.1074/jbc.M114.566117. Epub 2014 Apr 10" |
