title: Effects of phorbol ester and teleocidin on Ca2+-induced fusion of liposomes.
abstract: The effects of different types of lipid membrane defects on Ca2+-induced fusion of liposomes containing phosphatidylserine (PS) were investigated using fluorescent probes. Teleocidin enhanced the fusion of phospholipid vesicles in an assay system using terbium/dipicolinic acid during mixing of internal aqueous phases of vesicles upon fusion. 12-O-Tetradecanoylphorbol-13-acetate (TPA) suppressed the fusion. This latter phenomenon was also observed by measuring the excitation energy transfer. The promotion of membrane fusion by teleocidin was ascribed to dehydration of the membrane surface, the suppressive effect of TPA to desorption of Ca2+ from the membrane surface. Thus, Ca2+-induced fusion of PS vesicles was shown to be sensitive to defects of the membrane surface, but insensitive to defects of the hydrophobic core of the lipid membrane.
authors.affiliation: Department of Polymer Chemistry, Kyoto University, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Nam
authors.forename: S
authors.initials: S
authors.lastname: Kimura
authors.forename: H
authors.initials: H
authors.lastname: Fujiki
authors.forename: Y
authors.initials: Y
authors.lastname: Imanishi
mesh_terms: D002118:Calcium / Q000494:pharmacology*; D002784:Cholesterol; D004735:Energy Transfer; D005456:Fluorescent Dyes; D008081:Liposomes; D008235:Lyngbya Toxins / Q000494:pharmacology*; D008561:Membrane Fusion / Q000187:drug effects*; D010718:Phosphatidylserines; D010848:Picolinic Acids; D013050:Spectrometry, Fluorescence; D013725:Terbium; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
chemical_list: D005456:Fluorescent Dyes; D008081:Liposomes; D008235:Lyngbya Toxins; D010718:Phosphatidylserines; D010848:Picolinic Acids; D013725:Terbium; C022176:teleocidins; D002784:Cholesterol; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium; C004860:dipicolinic acid