| Title: | Soi3p/Rav1p functions at the early endosome to regulate endocytic trafficking to the vacuole and localization of trans-Golgi network transmembrane proteins |
| Author(s): | Sipos G; Brickner JH; Brace EJ; Chen L; Rambourg A; Kepes F; Fuller RS; |
| Address: | "Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0606, USA" |
| ISSN/ISBN: | 1059-1524 (Print) 1059-1524 (Linking) |
| Abstract: | "SOI3 was identified by a mutation, soi3-1, that suppressed a mutant trans-Golgi network (TGN) localization signal in the Kex2p cytosolic tail. SOI3, identical to RAV1, encodes a protein important for regulated assembly of vacuolar ATPase. Here, we show that Soi3/Rav1p is required for transport between the early endosome and the late endosome/prevacuolar compartment (PVC). By electron microscopy, soi3-1 mutants massively accumulated structures that resembled early endosomes. soi3Delta mutants exhibited a kinetic delay in transfer of the endocytic tracer dye FM4-64, from the 14 degrees C endocytic intermediate to the vacuole. The soi3Delta mutation delayed vacuolar degradation but not internalization of the a-factor receptor Ste3p. By density gradient fractionation, Soi3/Rav1p associated as a peripheral protein with membranes of a density characteristic of early endosomes. The soi3 null mutation markedly reduced the rate of Kex2p transport from the TGN to the PVC but had no effect on vacuolar protein sorting or cycling of Vps10p. These results suggest that assembly of vacuolar ATPase at the early endosome is required for transport of both Ste3p and Kex2p from the early endosome to the PVC and support a model in which cycling through the early endosome is part of the normal itinerary of Kex2p and other TGN-resident proteins" |
| Keywords: | Cation Transport Proteins/analysis/metabolism Cytoplasmic Vesicles/*physiology Endocytosis/genetics/*physiology Endosomes/physiology GTP-Binding Proteins/metabolism Membrane Proteins/analysis/genetics/*metabolism/*physiology Mutation/genetics Proprotein C; |
| Notes: | "MedlineSipos, Gyorgy Brickner, Jason H Brace, E J Chen, Linyi Rambourg, Alain Kepes, Francois Fuller, Robert S eng R01 GM039697/GM/NIGMS NIH HHS/ P30 CA046592/CA/NCI NIH HHS/ P30 CA46592/CA/NCI NIH HHS/ GM-50915/GM/NIGMS NIH HHS/ R01 GM050915/GM/NIGMS NIH HHS/ GM-39697/GM/NIGMS NIH HHS/ Research Support, U.S. Gov't, P.H.S. 2004/04/20 Mol Biol Cell. 2004 Jul; 15(7):3196-209. doi: 10.1091/mbc.e03-10-0755. Epub 2004 Apr 16" |
