title: Biochemical properties of platelet microparticle membranes formed during exocytosis resemble organelles more than plasma membrane.
abstract: Studies of [3H]glycerol turnover in phosphatidylcholine (PC) in platelets revealed two metabolic pools, a 'low turnover PC' in collagen-induced microparticles with specific radioactivity only 10% of that found in the 'high turnover PC' of bulk platelet PC. Isolated organelle fractions of [3H]glycerol-labelled platelets contained [3H]PC with specific radioactivities about 20% of that in membrane fractions. These results together with studies on distribution of concanavalin A-FITC and GPlb, a plasma membrane receptor, indicate that microparticles formed during exocytosis are not simple vesiculations of plasma membrane, but they seem rather to originate from a relatively metabolically static membrane pool not accessible to extracellular reagents.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Bergen, Arstadveien 19, 5009, Bergen, Norway.
authors.forename: Beata
authors.initials: B
authors.lastname: Olas
authors.forename: Kerstin
authors.initials: K
authors.lastname: Lundell
authors.forename: Holm
authors.initials: H
authors.lastname: Holmsen
authors.forename: Miriam H
authors.initials: MH
authors.lastname: Fukami
mesh_terms: D001792:Blood Platelets / Q000737:chemistry* / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry* / Q000378:metabolism; D003208:Concanavalin A / Q000493:pharmacokinetics; D005089:Exocytosis / Q000502:physiology*; D005434:Flow Cytometry; D016650:Fluorescein-5-isothiocyanate / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D005456:Fluorescent Dyes / Q000493:pharmacokinetics; D005990:Glycerol / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000032:analysis / Q000378:metabolism; D015388:Organelles / Q000737:chemistry* / Q000378:metabolism; D010713:Phosphatidylcholines / Q000737:chemistry / Q000378:metabolism; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000032:analysis / Q000378:metabolism; D013347:Subcellular Fractions / Q000737:chemistry; D014316:Tritium
chemical_list: D005456:Fluorescent Dyes; D010713:Phosphatidylcholines; D019038:Platelet Glycoprotein GPIb-IX Complex; C042784:fluorescein isothiocyanate-concanavalin A; D014316:Tritium; D003208:Concanavalin A; D007770:L-Lactate Dehydrogenase; D016650:Fluorescein-5-isothiocyanate; D005990:Glycerol