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The role of Ypt/Rab GTPases in Traffic Coordination
Author(s) -
Segev Nava,
Lipatova Zhanna,
Taussig David,
Kim Jane
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.355.1
Subject(s) - rab , microbiology and biotechnology , golgi apparatus , gtpase , effector , vesicle , vesicular transport protein , vesicular transport proteins , biology , endosome , biochemistry , intracellular , membrane , vacuolar protein sorting , endoplasmic reticulum
Transport between cellular compartments is mediated by vesicles that bud from one compartment and fuse with the next. Ypt/Rab GTPases and their effectors mediate all the known aspects of vesicular transport, from formation and motility, to targeting and fusion. An attractive idea is that in addition to regulating individual transport steps, Ypt/Rabs also integrate these steps into whole pathways and coordinate them with other cellular processes. In yeast, three Ypts regulate the exocytic pathway: Ypt1 regulates entry to the Golgi, Ypt31/32 control exit from the Golgi, and Sec4 regulates fusion of Golgi vesicles with the plasma membrane (PM). We have uncovered three types of Ypt‐mediated coordination mechanisms. First, we found that Ypt31/32 and Sec4 interact with common proteins to couple Ypt31/32‐mediated vesicle formation and motility with Sec4‐mediated vesicle tethering and fusion. Second, we propose that sequential activation of Ypt1 and Ypt31/32 by the modular complex TRAPP coordinates Golgi entry and exit, thus integrating these two transport steps into a whole pathway. Third, we identified novel effectors of Ypt1 and Ypt31/32 that coordinate the exocytic pathway with other cellular process like autophagy and PM recycling. In summary, we propose Ypt/Rab interactions and sequential activation as mechanisms by which these highly conserved GTPases coordinate trafficking inside cells.