Ypt31/32 GTPases and their novel F-box effector protein Rcy1 regulate protein recycling.
Ypt/Rab GTPases control various aspects of vesicle formation and targeting via their diverse effectors. We report a new role for these GTPases in protein recycling through a novel effector. The F-box protein Rcy1, which mediates plasma membrane recycling, is identified here as a downstream effector of the Ypt31/32 GTPase pair ... because it binds active GTP-bound Ypt31/32 and colocalizes with these GTPases on late Golgi and endosomes. Furthermore, Ypt31/32 regulates the polarized localization and half-life of Rcy1. This suggests that Ypt/Rabs can regulate the protein level of their effectors, in addition to the established ways by which they control their effectors. We show that like Rcy1, Ypt31/32 regulate the coupled phosphorylation and recycling of the plasma membrane v-SNARE Snc1. Moreover, Ypt31/32 and Rcy1 regulate the recycling of the furin-homolog Kex2 to the Golgi. Therefore, Ypt31/32 and Rcy1 mediate endosome-to-Golgi transport, because this is the only step shared by Snc1 and Kex2. Finally, we show that Rcy1 physically interacts with Snc1. Based on this result and because F-box proteins serve as adaptors between specific substrates and ubiquitin ligases, we propose that Ypt31/32 GTPases regulate the function of Rcy1 in the phosphorylation and/or ubiquitination of proteins that recycle through the Golgi.
Mesh Terms:
Blotting, Western, Endosomes, F-Box Proteins, Glutathione Transferase, Golgi Apparatus, Membrane Proteins, Microscopy, Fluorescence, Models, Biological, Phosphorylation, Plasmids, Proprotein Convertases, Protein Binding, Protein Processing, Post-Translational, Protein Structure, Tertiary, R-SNARE Proteins, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Subcellular Fractions, Temperature, Two-Hybrid System Techniques, Ubiquitin, Vesicular Transport Proteins, rab GTP-Binding Proteins
Blotting, Western, Endosomes, F-Box Proteins, Glutathione Transferase, Golgi Apparatus, Membrane Proteins, Microscopy, Fluorescence, Models, Biological, Phosphorylation, Plasmids, Proprotein Convertases, Protein Binding, Protein Processing, Post-Translational, Protein Structure, Tertiary, R-SNARE Proteins, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Subcellular Fractions, Temperature, Two-Hybrid System Techniques, Ubiquitin, Vesicular Transport Proteins, rab GTP-Binding Proteins
Mol. Biol. Cell
Date: Jan. 01, 2005
PubMed ID: 15537705
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