Ral GTPases regulate exocyst assembly through dual subunit interactions.
Ral GTPases have been implicated in the regulation of a variety of dynamic cellular processes including proliferation, oncogenic transformation, actin-cytoskeletal dynamics, endocytosis, and exocytosis. Recently the Sec6/8 complex, or exocyst, a multisubunit complex facilitating post-Golgi targeting of distinct subclasses of secretory vesicles, has been identified as a bona fide Ral effector complex. Ral GTPases regulate exocyst-dependent vesicle trafficking and are required for exocyst complex assembly. Sec5, a membrane-associated exocyst subunit, has been identified as a direct target of activated Ral; however, the mechanism by which Ral can modulate exocyst assembly is unknown. Here we report that an additional component of the exocyst, Exo84, is a direct target of activated Ral. We provide evidence that mammalian exocyst components are present as distinct subcomplexes on vesicles and the plasma membrane and that Ral GTPases regulate the assembly interface of a full octameric exocyst complex through interaction with Sec5 and Exo84.
Moskalenko
Serge
S
Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75235-9039, USA.
Tong
Chao
C
Rosse
Carine
C
Mirey
Gladys
G
Formstecher
Etienne
E
Daviet
Laurent
L
Camonis
Jacques
J
White
Michael A
MA
D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D006801:Humans; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000378:metabolism*; D011485:Protein Binding; D021122:Protein Subunits / Q000378:metabolism*; D022142:Secretory Vesicles / Q000378:metabolism; D014162:Transfection; D033921:Vesicular Transport Proteins; D020725:ral GTP-Binding Proteins / Q000378:metabolism / Q000502:physiology*
D002352:Carrier Proteins; C470182:EXOC2 protein, human; C490685:EXOC3 protein, human; C489607:EXOC4 protein, human; C480857:EXOC8 protein, human; D046911:Macromolecular Substances; D008565:Membrane Proteins; D021122:Protein Subunits; D033921:Vesicular Transport Proteins; D020725:ral GTP-Binding Proteins