Sec6/8 complex regulates delivery of exocytic vesicles to plasma membrane docking sites, but how it is recruited to specific sites in the exocytic pathway is poorly understood. We identified an Sec6/8 complex on trans-Golgi network (TGN) and plasma membrane in normal rat kidney (NRK) cells that formed either fibroblast- (NRK-49F) or epithelial-like (NRK-52E) intercellular junctions. At both TGN and plasma membrane, Sec6/8 complex colocalizes with exocytic cargo protein, vesicular stomatitis virus G protein (VSVG)-tsO45. Newly synthesized Sec6/8 complex is simultaneously recruited from the cytosol to both sites. However, brefeldin A treatment inhibits recruitment to the plasma membrane and other treatments that block exocytosis (e.g., expression of kinase-inactive protein kinase D and low temperature incubation) cause accumulation of Sec6/8 on the TGN, indicating that steady-state distribution of Sec6/8 complex depends on continuous exocytic vesicle trafficking. Addition of antibodies specific for TGN- or plasma membrane–bound Sec6/8 complexes to semiintact NRK cells results in cargo accumulation in a perinuclear region or near the plasma membrane, respectively. These results indicate that Sec6/8 complex is required for several steps in exocytic transport of vesicles between TGN and plasma membrane.
Sec6/8 complexes on trans-Golgi network and plasma membrane regulate late stages of exocytosis in mammalian cells
Charles Yeaman's present address is Department of Anatomy and Cell Biology, University of Iowa, Iowa City, IA 52242.
Kent Grindstaff's present address is Xenoport, Inc., Department of Discovery Biology, 2631 Hanover St., Palo Alto, CA 94304.
Jessica Wright's present address is Department of Biological Sciences, Stanford University, Stanford, CA 94305.
Abbreviations used in this paper: BFA, brefeldin A; GFP, green fluorescent protein; NRK, normal rat kidney; ts, temperature sensitive; VSVG, vesicular stomatitis virus G protein.
Charles Yeaman, Kent K. Grindstaff, Jessica R. Wright, W. James Nelson; Sec6/8 complexes on trans-Golgi network and plasma membrane regulate late stages of exocytosis in mammalian cells . J Cell Biol 12 November 2001; 155 (4): 593–604. doi: https://doi.org/10.1083/jcb.200107088
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