Fluorescence approaches to the study of the actin-nucleating and bundling activities of synapsin I

F. Valtorta, P. E. Ceccaldi, F. Grohovaz, E. Chieregatti, R. Fesce, F. Benfenati

Research output: Contribution to journalArticle


Synapsin I is a neuron-specific phosphoprotein which binds to small synaptic vesicles and actin in a phosphorylation-dependent fashion. We have analyzed the ability of synapsin I to interact with actin monomers and filaments using purified proteins derivatized with fluorescent probes. Synapsin I accelerates the initial rate of actin polymerization and increases the final steady-state levels of polymerized actin. The fraction of total actin polymerized by synapsin I strongly depends on the synapsin I-actin ratio. We have visualized the actin-bundling activity of synapsin I using a non-perturbing method, video-enhanced microscopy of fluoresceinated synapsin I and actin filaments. Our findings suggest that synapsin I exerts a control on the physical characteristics of the cytoskeletal network of the nerve terminal and are consistent with the proposed role of synapsin I in mediating the interaction of synaptic vesicles with actin.

Original languageEnglish
Pages (from-to)117-122
Number of pages6
JournalJournal of Physiology Paris
Issue number2
Publication statusPublished - 1993



  • actin polymerization
  • protein phosphorylation
  • pyrenyl-actin
  • synaptic vesicles

ASJC Scopus subject areas

  • Physiology (medical)
  • Neuroscience(all)

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