title: Synapsin IIa bundles actin filaments.
abstract: Synapsins are neuron-specific phosphoproteins associated with small synaptic vesicles in the presynaptic nerve terminal. Synapsin I, which has been demonstrated to bundle F-actin in vitro, has been postulated to regulate neurotransmitter release by cross-linking synaptic vesicles to the actin cytoskeleton. To investigate the possible interaction of synapsin II with actin filaments, we expressed synapsin II in Spodoptera frugiperda and High Five insect cells using a recombinant baculovirus. Purified recombinant synapsin IIa was incubated with F-actin, and bundle formation was evaluated by light scattering and electron microscopy. Synapsin IIa was found to bundle actin filaments. Dose-response curves indicated that synapsin IIa was more potent than synapsin I in bundling actin filaments. These data suggest that synapsin IIa may cross-link synaptic vesicles and actin filaments in the nerve terminal.
authors.affiliation: Laboratory of Molecular and Cellular Neuroscience, Rockefeller University, New York, New York 10021.
authors.forename: T J
authors.initials: TJ
authors.lastname: Chilcote
authors.forename: Y L
authors.initials: YL
authors.lastname: Siow
authors.forename: E
authors.initials: E
authors.lastname: Schaeffer
authors.forename: P
authors.initials: P
authors.lastname: Greengard
authors.forename: G
authors.initials: G
authors.lastname: Thiel
mesh_terms: D000199:Actins / Q000378:metabolism / Q000648:ultrastructure*; D000818:Animals; D002460:Cell Line; D007313:Insecta; D008027:Light; D008854:Microscopy, Electron; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism / Q000648:ultrastructure; D012542:Scattering, Radiation; D018411:Spodoptera; D016704:Synapsins / Q000302:isolation & purification / Q000378:metabolism / Q000648:ultrastructure*; D014162:Transfection
chemical_list: D000199:Actins; D011994:Recombinant Proteins; D016704:Synapsins