title: Sphingomyelin is sorted at the trans Golgi network into a distinct class of secretory vesicle.
abstract: One of the principal functions of the trans Golgi network (TGN) is the sorting of proteins into distinct vesicular transport carriers that mediate secretion and interorganelle trafficking. Are lipids also sorted into distinct TGN-derived carriers? The Golgi is the principal site of the synthesis of sphingomyelin (SM), an abundant sphingolipid that is transported. To address the specificity of SM transport to the plasma membrane, we engineered a natural SM-binding pore-forming toxin, equinatoxin II (Eqt), into a nontoxic reporter termed Eqt-SM and used it to monitor intracellular trafficking of SM. Using quantitative live cell imaging, we found that Eqt-SM is enriched in a subset of TGN-derived secretory vesicles that are also enriched in a glycophosphatidylinositol-anchored protein. In contrast, an integral membrane secretory protein (CD8α) is not enriched in these carriers. Our results demonstrate the sorting of native SM at the TGN and its transport to the plasma membrane by specific carriers.
authors.affiliation: Department of Cell Biology, Yale School of Medicine, New Haven, CT 06520.
authors.forename: Yongqiang
authors.initials: Y
authors.lastname: Deng
authors.affiliation: Department of Cell Biology, Yale School of Medicine, New Haven, CT 06520.
authors.forename: Felix E
authors.initials: FE
authors.lastname: Rivera-Molina
authors.affiliation: Department of Cell Biology, Yale School of Medicine, New Haven, CT 06520.
authors.forename: Derek K
authors.initials: DK
authors.lastname: Toomre
authors.affiliation: Department of Cell Biology, Yale School of Medicine, New Haven, CT 06520 christopher.burd@yale.edu.
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Burd
mesh_terms: D001693:Biological Transport, Active / Q000187:drug effects / Q000502:physiology; D016827:CD8 Antigens / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism*; D003064:Cnidarian Venoms / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D022142:Secretory Vesicles / Q000235:genetics / Q000378:metabolism*; D013109:Sphingomyelins / Q000235:genetics / Q000378:metabolism*; D021601:trans-Golgi Network / Q000235:genetics / Q000378:metabolism*
chemical_list: D016827:CD8 Antigens; C409469:CD8 antigen, alpha chain; D003064:Cnidarian Venoms; D013109:Sphingomyelins; C012307:equinatoxin
keywords: Golgi apparatus; equinatoxin; secretion; sphingomyelin