Ypt31/32 GTPases and their novel F-box effector protein Rcy1 regulate protein recycling

Mol Biol Cell. 2005 Jan;16(1):178-92. doi: 10.1091/mbc.e04-03-0258. Epub 2004 Nov 10.

Abstract

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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Blotting, Western
  • Endosomes / metabolism
  • F-Box Proteins
  • Glutathione Transferase / metabolism
  • Golgi Apparatus / metabolism
  • Membrane Proteins / metabolism*
  • Microscopy, Fluorescence
  • Models, Biological
  • Phosphorylation
  • Plasmids / metabolism
  • Proprotein Convertases / metabolism
  • Protein Binding
  • Protein Processing, Post-Translational
  • Protein Structure, Tertiary
  • R-SNARE Proteins
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Saccharomyces cerevisiae Proteins / physiology*
  • Subcellular Fractions
  • Temperature
  • Two-Hybrid System Techniques
  • Ubiquitin / metabolism
  • Vesicular Transport Proteins
  • rab GTP-Binding Proteins / physiology*

Substances

  • F-Box Proteins
  • Membrane Proteins
  • R-SNARE Proteins
  • RCY1 protein, S cerevisiae
  • SNC1 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Ubiquitin
  • Vesicular Transport Proteins
  • Glutathione Transferase
  • Proprotein Convertases
  • KEX2 protein, S cerevisiae
  • YPT31 protein, S cerevisiae
  • YPT32 protein, S cerevisiae
  • rab GTP-Binding Proteins