title: Molecular dissection of alpha- and dense-core granule secretion of platelets.
abstract: Upon activation, platelets release many active substances stored in alpha- and dense-core granules. However, the molecular mechanisms governing the regulated exocytosis are not yet fully understood. We have established an assay system using streptolysin-O-permeabilized platelets to analyze the Ca2+-induced secretions of von Willebrand factor stored in alpha-granules and [3H]5-hydroxytryptamine (5-HT) in dense-core granules. Using the assay, we found that small GTPase Rab4 regulates alpha-, but not dense-core, granule secretion in platelets. Furthermore, we purified a cytosolic essential protein and currently are analyzing its function.
authors.affiliation: Department of Geriatric Medicine, Graduate School of Medicine, Kyoto University, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Yoshioka
authors.forename: H
authors.initials: H
authors.lastname: Horiuchi
authors.forename: R
authors.initials: R
authors.lastname: Shirakawa
authors.forename: H
authors.initials: H
authors.lastname: Nishioka
authors.forename: A
authors.initials: A
authors.lastname: Tabuchi
authors.forename: T
authors.initials: T
authors.lastname: Higashi
authors.forename: A
authors.initials: A
authors.lastname: Yamamoto
authors.forename: T
authors.initials: T
authors.lastname: Kita
mesh_terms: D001792:Blood Platelets / Q000502:physiology* / Q000648:ultrastructure; D003594:Cytoplasmic Granules / Q000235:genetics* / Q000502:physiology; D006801:Humans; D012701:Serotonin / Q000097:blood; D020695:rab4 GTP-Binding Proteins / Q000097:blood / Q000235:genetics; D014841:von Willebrand Factor / Q000378:metabolism
chemical_list: D014841:von Willebrand Factor; D012701:Serotonin; D020695:rab4 GTP-Binding Proteins